COMPUTER OPERATIONS & PACKAGES - KENYA ...

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COMPUTER OPERATIONS &

PACKAGES

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COMPUTER OPERATIONS & PACKAGES

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DEFINE A COMPUTER

� An electronic machine that works under the control of stored programs to accept, process

& output data/information for use by the operator.

� A device that accepts data, processes the data in accordance with a stored program,

generates results, and usually consists of input, output, storage, and arithmetic, logic, and

control units.

� A functional unit that can perform substantial computation, including numerous arithmetic

operations or logic operations, without human intervention during a run. � It is an electronic device/machine that accepts data(raw facts & figures) asinput and

processes (works on it) to produce information(data converted tomeaningful form) as output.

A computer performs a number of functions:

• Input (Data)

The computer accepts data from outside for processing. Input is the raw information

entered into a computer from the input devices.

• Processing

The computer performs operations on the data that it holds internally. Processing is the

operation of data as per given instruction. It is totally internal process of the computer

system.

• Output

The computer produces information for external use. Output is the processed data given

by computer after data processing. Output is also called as Result. We can save these

results in the storage devices for the future use.

• Storage

The computer stores data before, during and after processing.

• Communication

The computer can send or receive data to or from other computers when it is connected

on a network The computer is made up of hardware, software and peripheral devices.

Hardware- refers to the tangible, physical and mechanical components of a computer.

Software- refers to the intangible computer components, which are the programs or instructions of

the computer. Everything that a computer does, it acts under instructions written out as computer

programs. The hardware needs these instructions to function

Computer program:

• A set of instructions, written in a specific programming language, which a computer follows in processing data, performing an operation, or solving a logical problem. See also

software.

• A computer program is a set of statements or instructions to be used directly or indirectly in a computer in order to bring about a certain result.

NB: Software alone is useless, so is the hardware. The two are inseparable.

Peripheral Devices- These are devices that are external (not part of the computer) but can be

connected to a computer. They are not essential for the functioning of the computer but can be


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connected to the computer for specific reasons. Examples are scanners, modems, printers,

speakers, digital cameras, etc.

DATA PROCESSING

Used specifically, data processing may refer to a discrete step in the information processing cycle in which data is acquired, entered, validated, processed, stored, and output, either in response to

queries or in the form of routine reports; the processing is the step that organizes the information in

order to form the desired output. Used in a more general sense, data processing may also refer to

the act of recording or otherwise handling one or more sets of data, and is often performed with

the use of computers. The word data is commonly used to mean “information” and often suggests

large amounts of information in a standardized format. Data may consist of letters, numbers,

equations, dates, images, and other material, but does not usually include entire words.

CATEGORIES OF DATA PROCESSING

Data is processed to get the required results. Different operations may be performed on data.

Therefore, data processing is defined as:

"A sequence of operations on data to convert it into useful information is called data processing".

The important operations that can be performed on data are:

• Arithmetic and logical operations on data to get required results.

• To send and receive data from one location to another.

• Classification of data.

• Arranging data into a specific order etc.

The data processing is divided into three categories or levels.

1. Manual Data Processing

In manual data processing, data is processed manually without using any machine or tool to get

required result. In manual data processing, all the calculations and logical operations are manually

performed on the data. Similarly, data is manually transferred from one place to another. This

method of data processing is very slow and errors may occur in the output.

In Zimbabwe, data is still processed manually in many small business firms as well as government

offices & institutions.

In manual data processing data is processed manually. No machine or tool is used.

All the calculations on data are performed manually. This is a slow method and errors may occur.

This is an old method. It was used before the invention of calculators. But data is still processed

manually in many small shops.


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Example: A book seller (a small book shop) records his daily transactions manually. He prepares bills

by pen, paper and carbon paper (no doubt, brain is the main data processor in this case). At the

end of day he will use carbon copies made on a particular date to know how many books he sold

and how much income he got.

2. Mechanical Data Processing

In mechanical data processing, data is processed by using different tools like calculators or other

mechanical devices. This method of data processing is faster and more accurate than manual

data processing.

Mechanical data processing is more accurate than manual. Calculators, computer programs and

other devices are used on the data however someone still has to step in between operations.

In mechanical data processing data is processed with the help of devices or machines. These

machines that help the people in data processing may be calculators and type writers etc.

Obviously, this method is faster easier and more accurate than manual data processing.

Example: Book seller can use a calculator to speed up his data processing system. There will be a

less chance of errors in calculations. Bill calculations will be much more faster with a calculator and

easier too.

3. Electronic Data Processing

It is the modern technique to process data. The data is processed through computer. Data and set

of instructions are given to the computer as input and the computer automatically processes the

data according to the given set of instructions.

The computer is also known as electronic data processing machine. This method of processing

data is very fast and accurate. Now-a-days, the data is processed and analyzed through

computers. For example, the results of students are prepared through computer; in banks accounts

of customers are processed through computers etc.


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It is the latest and fastest method of data processing. Data is processed with the help of computer.

First of all, data and set of instructions are given to the computer. Computer gives output results

after processing the data according to instructions. This method of data processing is very fast and

accurate. Electronic data processing is used in banks and business firms, Government offices,

colleges, schools, universities, businesses and other institutes. Electronic data processing is being

used in almost every field of life. Example: Suppose there are 800 students in a college. There is a

manual library system in this college. If we want to know which students have not returned books

since one year? We will have to search registers for 800 students’ record. But computer can do this

job within seconds.

In short, we can say that: Electronic data processing:

i) is more fast ii) is less time consuming iii) can process large amounts of data easily iv) can present information in more attractive way

v) will give 100 % error free results, if input and instructions are accurate.

THE DATA PROCESSING CYCLE

The data processing cycle is the order in which data is processed. There are four stages:-

After collecting data, it is processed to convert into information. The data is processed again and

again until accurate result is achieved. This is called data processing cycle.

Data processing cycle involves following three basic activities:


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1. Input

2. Processing

3. Output

1. INPUT

It is the process in which collected data is given to computer after converting into binary form.

Input step can be further divided into following steps:

i) Planning

Here objectives of data processing are defined. For example, in examination system, objective is to

process student examination data to get result cards.

ii) Data Collecting

Here data is collected. Data is the raw material for data processing. This must be accurate for

getting accurate results.

iii) Input

Here data is entered into computer.

iv)Verification

Here collected data is verified to determine whether it is valid for processing. For example marks

must be in numeric form.

v) Coding

Data is stored in computer in binary form. Here data is converted (or coded) into computer readable (binary) form.

2. PROCESSING

Now data is ready for processing. We process collected data to convert into information. Some

important activities in processing are as following:

i) Data Classification

Here data is classified into different groups or sub-groups. So that it can be handled easily and

separately. For example if we collect data about students of a college we will divide them into

D.Com and B.Com class groups.

ii) Data Sorting

Here data is arranged in some order. So that it can be accessed quickly. For example we can sort

student data by Roll number or name.

iii) Data Calculation/Processing


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Here arithmetic and logical operations are performed on data to get the required result. For

example total marks of each student are calculated.

3. OUTPUT

After completing the processing, output is received. Output step involves following steps:

i) Testing

The results are tested to find if they are according to requirements. And any errors are removed. If

results are not satisfactory then we repeat above-mentioned steps again and again until the

accurate results are found.

ii) Summarizing

Huge results are summarized to make them short and precise.

iii) Storing results

The results are stored properly on secondary storage devices for future use.

iv)Output the result

Here output is produced as softcopy on screen or as hard copy as printout. Information is sent to

different places as needed.

v) Feed Back

In this step we take comments from users about output results. If results are not satisfactory then we

repeat above-mentioned steps again and again until the accurate results are found.

What is the Information Processing Cycle?

If one has to look at the information processing cycle diagram, he will see that there are four

events in the sequence of events. The sequence of events, which make up the cycle are:

Input Processing Output Storage


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In some of the events, certain sub-events can also be added. Without wasting any more time we

will turn towards the cycle in detail.

Input This is the first event in the cycle. This stage involves collection of data from the outside or also from

within the system. One can break this stage into three more stages, namely acquisition, data entry

and validation. After the data has been acquired from the source, it is entered into the current

system, upon which the data is validated, so that correct results are given at the end of the cycle.

The input devices are many. The commonly used input devices are computer keyboard, bar code

readers, scanners, output from another system, etc.

Processing In this stage the computer processes the minutest details entered. This processing makes the data

entered usable. If the computer was not to process the data, it would not be of any use and it

would also be a big mess of data. For example, if the spreadsheet was not to process the data,

then the data in the spreadsheet would only be a mess of numbers. The spreadsheet is a program

which gives the data out back to the user in the usable form. The system used for processing, along

with the data entered will decide the kind of output, which the user will get.

Output If you have to look at the diagram of information processing cycle, the step after processing is the

output stage. The processed information is now transmitted to the user. This stage can also be

further divided. After processing the data, there can be further interactive queries asked or routine

reports can be given. There are different forms in which the output can be given to the user. There

can be print report, which may be given to the user. The output can also be given in the form of

audio, video as well. In some cases, the results may only be displayed on the computer monitor.

Storage After the data has been processed, along with the output to the user, the data is also stored.

Different computer storage devices can be used for the same. Some of the commonly used data

storage methods are disk storage, tertiary storage, etc. Storing the data also serves another

purpose. You will not have to repeat the entire cycle again. Often the storage is done in both

digital as well as hard copy format. At the same time, backup of the digital format is also maintained, which can be retrieved in case of system crash.

The most important advantage of this cycle is that the information is processed quickly. At the

same time retrieving the data is an easy task as well. The processed information can further be

passed unto the next stage directly in case the need be. The necessary data is stored, which helps

in avoiding duplication of data as well as time.

ATTRIBUTES OF GOOD INFORMATION Quality Required

Commentary

Relevant The information obtained and used should be needed for decision-making. it

doesn't matter how interesting it is. Businesses are often criticised for producing too

much information simply because their information systems can "do it". A good way

of ensuring relevance is to closely define the objectives of any information reports.

Another way to improve relevance is to produce information that focuses on

"exceptions" - e.g. problems, high or low values, where limits have been exceeded.

Up-to-date Information needs to be timely if it is to be actioned. For example, the manager of

a large retail business needs daily information on how stores are performing, which

products are selling well (or not) so that immediate action can be taken. To

improve the speed with which information is produced, businesses usually need to

look at upgrading or replacing their information systems.


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Accurate As far as possible, information should be free from errors (e.g. the figures add up;

data is allocated to the correct categories). The users of information should be

informed whenever assumptions or estimates have been used. Accruate

information is usually a function of accurate data collection. If information needs to

be extremely accurate, then more time needs to be allocated for it to be checked.

However, businesses need to guard against trying to produce "perfect" information

- it is often more important for the information to be up-to-date than perfect.

Meet the needs of the User

Users of information have different needs. The managing director doesn't have time

to trawl through thick printouts of each week's production or sales listings - he or she

wants a summary of the key facts. The quality control supervisor will want detailed

information about quality testing results rather than a brief one-line summary of how

things are going. It is a good idea to encourage users to help develop the style and

format of information reporting that they require.

Easy to use and understand

Information should be clearly presented (e.g. use summaries, charts) and not too

long. It also needs to be communicated using an appropriate medium (e.g. email,

printed report, presentation. Businesses should also consider developing "templates"

which are used consistently throughout the organisation - so that users get used to

seeing information in a similar style.

Worth the cost Often forgotten. Information costs money. Data is costly to collect, analyse and report. Information takes time to read and assimilate. All users should question

whether the information they recieve/have requested is worthwhile

Reliable Information should come from authoritative sources. It is good practice to quote

the source used - whether it be internal or external sources. If estimates or

assumptions have been applied, these should be clearly stated and explained.

1) Valid 2) Fit for use 3) Accessible 4) Cost effective 5) Understandable 6) Time

DATA � Relationship between Data and Information

� Data is raw information

� a collection of facts from which conclusions may be drawn; "statistical data"

INFORMATION � Data that has been processed to add or create meaning and hopefully

knowledge for the person who receives it. Information is the output of information

systems.

� Organized data which is understood to have significance and meaning

� Methods of data collection {see Systems Analysis & Design} � Questionnaires

� Observation

� Sampling

� Interviews � Written documents & research

MAKE NOTES ON:

� Verification o The act of reviewing, inspecting, testing, checking, auditing, or otherwise establishing

and documenting whether items, processes, services, or documents conform to

specified requirements. o An effort to test the accuracy of the questionnaire response data. The concern is

uniquely with data accuracy and deals with neither the reliability nor the validity of

measures. � Validation


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o The process of evaluating software at the end of the software development process to

ensure compliance with software requirements. The techniques for validation are

testing, inspection and reviewing. o Determination of the correctness of the products of software development with

respect to the user needs and requirements.

BENEFITS OF COMPUTERS

With the advent of new technology, various processes have been very dependent with automation. As the years go by, more and more inventions are introduced in the market and in the

society all for one purpose - convenience. Let us tackle for instance two of the most influential

aspects of this modern world; the societal and the entrepreneurial feature. These two have been

greatly influenced by the advancements that are continuously taking place. With that said, a

number of essential advantages are becoming more evident in these two facets. To further draw a

clearer picture on the benefits of computers on each of the mentioned aspect, here are brief

descriptions of each.

Business

Multitasking - The modern multimedia options enable entrepreneurs to work various tasks all at the

same time. Workers in the offices can use the DVD-ROM while installing Printer Cartridges and

running a scan thus making workload easier and more convenient. With such, the need for an

outsourcing company would not be essential because all the tasks can be addressed by majority

of the manpower available.

Cost-effective - These computers have allowed companies to cut costs on payroll and individual

office equipment. Because of the efficient and fast outputs coupled with less expenditures on

operations, revenues are then maximized. Good examples for this benefit are the email messaging

that lessens postage costs and video conferencing that decreases travel allowances for employees.

Increased access to the market - Because of the Internet, businesses have opened their doors to

various opportunities all around the globe. For those selling goods, then customers can readily

purchase them over the Web thus resulting to an increase in the sales of the firm. Also, advertising

strategies are well utilized because by just simply posting a good multimedia scheme over the

Web, firms can readily maximize their marketing plans.

Organization- Different types of software are utilized to store a wide array of documents that must

be kept confidential for years. With the help of computers, storage and retrieval of files are easily

done with just a click of the mouse.

Those are the benefits that businesses are enjoying from the various innovations in computers now.

Further, here are the societal advantages.

Education edge- Nowadays, PC's enable students to search from a wide range of online resources.

Hence, they can save time on looking for the best Internet source that can answer each of the

queries. Instead of spending so much time looking for books, then this could answer the worries for

students who want to hasten their tasks. Also, a new trend in education is online teaching. Through the Web, people can freely enroll in a specific course provided that you get to pay the fees on the

specified date. This scheme can be very helpful for individuals who want to get a degree yet are

to busy to get into the usual classroom setting.

Communication benefit- Social networking sites, chat, and video conferencing sites are accessible

because of computers. People across the globe can now talk to their loved ones in real time with


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the help of these gadgets. What is good about this communication option is that it is more cost

effective than the usual telephone. By embracing such, people can now deliver messages and

create a copy of that using quality printer cartridge in just a second.

Job opportunities- These gadgets open up a wide array of workload for people. That is, experts are

needed in software and hardware maintenance and checks. With the increasing demand for

these professionals, unemployment is then lessened at a considerable percentage.

Home Entertainment- During weekends, you may utilize your personal computer to watch films

using its DVD-ROM. Aside from this, you may as well play games all throughout the day. You can

simply install a variety of files that you can use for the whole day of indoor fun. From the latest TV

shows to the more modern games, you can have them in your CPU just minutes.

Those are few of the numerous benefits of personal computers in our everyday lives. Knowing each

of those points will certainly allow you to see the importance of those gadgets in almost all processes that are taking place every day.

With this obvious dependence, it is also but essential to ensure that each of the systems are

working properly. This is because a single defect inside the CPU could mean serious impairment.

Hence, the specialists in repairs and maintenance can be tapped for their expertise.

ADDITIONAL

Without computers, there would be no Internet. Computers and the internet helped create a

global community where it is possible to instantly communicate with anyone around the globe.

You aren't just stuck being exposed to only those in your own community or country.

Various online knowledge sources including online encyclopaedias, open vast amounts of

information to people all over the world. This can even aid someone doing anything from a simple

homework assignment, to a complex research paper.

In the home, you can pay your bills online, without having to write a check or placing the bill in a

postage envelope. No chance of the payment getting lost in the mail, and no need to worry

about being assessed a late charge - as the bill has been paid and confirmed. People now listen

to music, get up to the minute live news reports, play games, watch movies, and even watch

television shows they might have missed.

You can buy products online that may not be available in your local shops.

Computer chips are used in many many things, including the portable cell-phone. And the internet led to Twitter, which was used recently by Iranians keeping communication and coordination

active against an oppressive regime.

In the business world, computers are used in every operation, function and activity of an

organization. This had led to improved productivity, greater collaboration, major improvements to

information management.

Computers help scientists calculate things faster and learn more about the world and universe. In

addition, this helps things get invented, like a video game system.

Computers are used heavily to improve accuracy, flexibility of planning, and speed in Engineering

work. Civil Engineering - Autocad and WaterCad.Mining engineering - Surface Deformation

Prediction Software.Mechanical engineering - SolidCad. Electrical Engineering - electric cycle

programs.

In the medical community, computers led to improved Hospital care. So in a sense, computers

have even helped extend the average lifespan of human beings.



LIMITATIONS

1. They are expensive.

2. If you have little knowledge of them, it is easy to get in a lot of trouble and quite literally destroy

your computer.

3. Depending on the OS and software/hardware installed, they can be difficult to maintain.

4. If you have the internet and don't have an Anti-Virus program, or at least an Anti-Spyware

program, surfing the web can ruin your day.

5. Nothing lasts forever.

Computer disadvantages are as follows; Violation of Privacy, it is crucial that personal and

confidential records stored in computers be protected properly. Impact on Labor Force, although

computers have improved productivity and created an entire industry with hundreds of thousands

of new jobs, the skills of hundreds of thousands employees are replaced by computers. Health

Risks, prolonged or improper computer use can lead to head injuries or disorders. Computer users

can protect themselves from health risks through proper workplace design, good posture while at

the computer, and appropriately spaced work breaks. Impact on the Environment, Computer

manufacturing processes and computer waste are depleting natural resources and polluting the

environment.

MAJOR COMPONENTS OF A COMPUTER SYSTEM

CPU

The CPU consists of the ALU & CU

KEY

Data Instructions

Command Flow

Control unit-issues

commands to computer elements & interpret stored

instructions

A. L.U. performs

arithmetic & logic

operations Output Unit Information after

processing

Main Memory-Holds

data & instructions & results

ofprocessing

-RAM

Input Unit Data & instructions

Backing/Auxiliary

Storage- supplements the

main storage.



DESCRIBE THE FUNCTIONS OF EACH COMPONENT.

Main memory Auxiliary or backup storage

Stores programs and data while computer is running

for current use

Store data or programs for later use

Main memory is fast and limited in capacity Slow and capacity vary

Cannot retain information when the computer is

switched off - Volatile

Non volatile

Memory directly connected to the CPU - not portable Portable- can be transported from one

machine to another.

Primary storage Secondary storage

PROVIDES FAST ACCESS ACCESS IS SLOW

Temporary Permanent

Computer cannot do or work without Can do or work without

PROCESSING DEVICE

The only processing device on a computer is The Central Processing unit known as the CPU. It is the main part of the computer as all other devices are built around it. It can be referred to as the heart

or brain behind the computer.

Functions of the Central Processing Unit (CPU)

a) It interprets the instruction in the program according to the type and sequence of processing operations that are to be performed on input data.

b) Performs the varied arithmetic and logic operations that are necessary to convert

input data into output information.

c) Stores intermediate results of data being processed on its registers.

d) Directs or controls output to all other devices (input, output, auxiliary storage units),

telling each what to do and when to do it.

CPU COMPONENTS

It consists of the control unit (CU) and Arithmetic and Logic Unit (ALU). In most computers

the two components - CU and ALU units - are combined in a unit called the

microprocessor (CPU).

The Control Unit The Control Unit manages input/output to and from the main memory and to and from

auxiliary storage units and output devices. It interprets instructions in their sequence,It

determines what is to be done to follow the instruction and, transmits to the appropriate

device directions specifying the work to be done. For example, it advises each input

device what data to transfer, when to transfer it, and when to send the data. It arranges

for data to move from the main memory to the ALU and spells out the calculating and

logic operations that are to be performed, and then arranges to send the processed

results to main storage or to an output device for printing or display.

The ALU The Arithmetic Logical Unit has 2 functions i.e. to perform calculations and logic operations

at a fast speed (measured in nanoseconds, i.e. billionths of a second). It consists of

registers (special storage locations to hold the data to be processed), and an

accumulator to store intermediate results of operations. Logic operations compare values

for greater, smaller or equal.

CPU speed



The CPU speed is measured in Megahertz (MHz) being millions of instructions that can be

executed per second (MIPS). Each computer has specified, the processor speed.

INPUT DEVICES

These are some devices that feed data into the computer for processing. Some examples

include:-

1. KEYBOARD

2. MOUSE

3. TRACKBALL

4. LIGHT PEN

5. TOUCH SCREEN

6. MODEM

7. SCANNER

8. MICROPHONE

9. BAR CODE READER

10. DIGITAL CAMERA

11. VIDEO DIGITISER 12. MAGNETIC INK CHARACTER RECOGNITION (MICR) 13. MAGNETC STRIPS OR STRIPES READER

14. KEY TO DISK 15. GRAPHICS TABLET 16. OCR 17. OMR

18. VOICE RECOGNITION SYSTEM

Storage devices can be used as input devices

a) KEYBOARD

The keyboard is an input device with an arrangement of keys, like those on a typewriter,

and an additional set of keys that fall into 5 basic categories:

1. Function keys- keys form the first row of keys. They perform special operations in

applications e.g. F7 activates Spell Checking Program in word processing and F1

activates the Help facility in any application.

2. Alphanumeric keys (like those on typewriter) are arranged in a QWERTY series. First

is a row of numbers with some characters like %^&*()@!~ above them, then letters

of the alphabet, the spacebar at the bottom, the Shift key on both the left and

right side of the Spacebar.

3. Numeric keypad- serves 2 functions. At the top of the keypad is the NumLock key,

which locks the keypad into Number mode when, pressed. When in Number mode, the keys function as number keys arranged like a standard calculator,

otherwise it is in Cursor control mode, which allows you to move the cursor up,

down, forward or backward by pressing the appropriate arrow key. When in cursor

mode you can also use the home, page up, page down, end, delete and insert

keys from Num Lock pad.

4. Cursor control keys are the arrow keys as well as Home, End, Ins, Page Up etc.

Their major function is to place the cursor in an appropriate position for reading,

appending or editing text.

5. Combination keys are the Shift Ctrl andAlt keys. On their own they are ineffective but combined with other keys they work. E.G. The Shift key, can be used to type to

type the $ sign (you would keep Shift pressed as you press the $ sign key once).

b) MOUSE


The mouse is both input and pointing device. It is a hand held device with a rotating ball

(trackball) underneath and Left & Right (the blinking item on your screen) around the screen and to click on objects. The trackball

is made from a ball in a socket, which is used to move the cursor on a screen. The cursor

moves in the direction the ball moves as it is rolled.

c) JOYSTICK The joystick is anInput device

e.g. Up, Down, Left or Right. It is normally used with computer games to control the

movements of objects on the screen.

d) LIGHT PEN

This is an Inputdevice. An electricaldeviceused with a monitor

ordinary pen. One writes on a monitor with it and it senses the light from the position on the

screen and transmits the information to the computer.

e) TOUCH-SENSITIVE SCREEN/ TOUCH PADInput deviceused in public information kiosks

point of interest to get what (s

Touchpad A small pressure- and motion

move the mouse pointer. When you move your finger across the pad, the mouse pointer

on the screen moves in the same direction. A touchpad is an alternative to a mouse.

A touchpad is operated by using your finger and dragging it across a flat surface; as yo

move your finger on the surface, the mouse cursor will move in that same direction, and

like most computer mice, the touchpad also has two buttons below the touch surface that

enables you to click like a standard mouse.

f) SCANNER – Input device It works like a photocopier but copies an image from text to computer mode

need for OCR (Optical Character Recognition) software to change the text into digital

form, and to be able to modify the scanned image.

g) MICROPHONE


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) underneath and Left & Right buttons, which enable the user to move the cursor

(the blinking item on your screen) around the screen and to click on objects. The trackball


he ball moves as it is rolled.

The joystick is anInput device. A leverinputdevice that can be moved in many directions,


movements of objects on the screen.

This is an Inputdevice. An electricaldeviceused with a monitor. It has the shape of an ordinary pen. One writes on a monitor with it and it senses the light from the position on the

screen and transmits the information to the computer.

SITIVE SCREEN/ TOUCH PAD Input deviceused in public information kiosks. Theuser simply touches the screen at the

point of interest to get what (s) he wants.

and motion-sensitive area on a portable computer that you can use to



A touchpad is operated by using your finger and dragging it across a flat surface; as yo



enables you to click like a standard mouse.

Input device ks like a photocopier but copies an image from text to computer mode

need for OCR (Optical Character Recognition) software to change the text into digital

form, and to be able to modify the scanned image.


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buttons, which enable the user to move the cursor

(the blinking item on your screen) around the screen and to click on objects. The trackball


A leverinputdevice that can be moved in many directions,


It has the shape of an

ordinary pen. One writes on a monitor with it and it senses the light from the position on the

Theuser simply touches the screen at the

sensitive area on a portable computer that you can use to



A touchpad is operated by using your finger and dragging it across a flat surface; as you



ks like a photocopier but copies an image from text to computer mode. There is need for OCR (Optical Character Recognition) software to change the text into digital


This is Input device. This is

words are into digital mode for storage. The sound can be played back.

h) DIGITAL CAMERA

This is Input device. It works like a standard camera except that it does not use

photographic film. The images are recorded digitally in the camera’s memory. Images are

transferred onto the computer, and can be printed.

MORE INPUT DEVICES

1. KEY TO DISK- An early stand-computer entry. The key to disk

was the first major breakthrough in data entry since the punch card.

2. BARCODE READER Barcodes are different groups of vertical bars that can be read by an optical

Barcodes are printed on nearly every product that you can buy. Shops use barcodes

because they are cheap to produce and very durable.

3. CONCEPT KEYBOARD This is a flat board that contains a grid of buttons. Each button can be programmed to

follow instructions. An overlay sheet is placed on the grid with an explanation for each

button. They are used in primary schools with young children. Many mod

restaurants have overlays with either a description or picture of the meals that are

available to make ordering easier.

4. DIGITAL CAMERA A digital camera allows you to take pictures and to store a digital photographic image

that can be read by a computer. You can then transfer the images directly from your

camera on to your computer.

5. GRAPHICS TABLET This consists of a flat pad (the tablet) on which the user draws with a special pen. As the user draws on the pad the image is created on the screen. Using a graphics tablet a

designer can produce very accurate on

6. MICR (MAGNETIC INK CHARACTER READER)Magnetic ink characters are the strange looking numbers that appear at the bottom of

cheques. These characters are used because they are very difficult to forge or damage.

Banks use MICR to read the numbers from the bottom of cheques to obtain

account numbers and bank sort codes.

7. MAGNETIC STRIP (OR STRIPE) READERMagnetic strips are built into many plastic cards such as

point cards and personal identity cards. The magnetic strip on the back of the card can

hold the personal details of the card owner and, with the necessary PIN, will allow access


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This is Input device. This is used in conjunction with voice recognition programs. It converts

words are into digital mode for storage. The sound can be played back.


The images are recorded digitally in the camera’s memory. Images are

transferred onto the computer, and can be printed.

-alone data entry machine that stored data on magnetickey to disk machine was the successor to the key-to-tape machine, which

was the first major breakthrough in data entry since the punch card.

Barcodes are different groups of vertical bars that can be read by an optical

Barcodes are printed on nearly every product that you can buy. Shops use barcodes

because they are cheap to produce and very durable.

This is a flat board that contains a grid of buttons. Each button can be programmed to


button. They are used in primary schools with young children. Many modern fast food


available to make ordering easier.

camera allows you to take pictures and to store a digital photographic image


camera on to your computer.

flat pad (the tablet) on which the user draws with a special pen. As the user draws on the pad the image is created on the screen. Using a graphics tablet a

designer can produce very accurate on-screen drawings.

MICR (MAGNETIC INK CHARACTER READER) Magnetic ink characters are the strange looking numbers that appear at the bottom of


Banks use MICR to read the numbers from the bottom of cheques to obtain dataaccount numbers and bank sort codes.

MAGNETIC STRIP (OR STRIPE) READER Magnetic strips are built into many plastic cards such as cheque guarantee cards, cash




15

used in conjunction with voice recognition programs. It converts


The images are recorded digitally in the camera’s memory. Images are

alone data entry machine that stored data on magnetic disk for tape machine, which

Barcodes are different groups of vertical bars that can be read by an optical scanner. Barcodes are printed on nearly every product that you can buy. Shops use barcodes

This is a flat board that contains a grid of buttons. Each button can be programmed to


ern fast food


camera allows you to take pictures and to store a digital photographic image


flat pad (the tablet) on which the user draws with a special pen. As the user draws on the pad the image is created on the screen. Using a graphics tablet a

Magnetic ink characters are the strange looking numbers that appear at the bottom of


data such as

cheque guarantee cards, cash-




to secure information e.g. bank account details

input into a computer system by a reader.

8. MIDI (MUSICAL INSTRUMENT DIGITAL INTERFACEA MIDI system allows you to attach a musical instrument to your computer, for example a

musical keyboard. You can then store a

the computer play it back to you.

9. OMR (OPTICAL MARK READERAn OMR reads marks made by pencil on a printed form into the computer. OMR systems

are suited to reading preselection sheets and multiple

OMR processing is popular for tests, where students receive a special card containing

several empty circles and a packet that contains the questions and possible answers to

each of the questions. The student must complete the test by using a pencil to fill in each

blank circle with what he or she believes is the correct answer. For example, if the answer is

"B", the student would have to fill in the "B Circle" in order to get the answer

10. SCANNER Hardware input device that allows a user to take an image or text and convert it into a

digital file, allowing the computer to read or display the scanned object. A scanner is

commonly connected to a computer USB, Firewire, Parallel, or SCSI port.

a cheap and common way of getting images into a computer. They can also be used

with OCR (Optical Character Recognition) softw

11. TOUCH SCREEN A touch screen is a special type of

crossing the screen. When the screen is touched (usually to choose an on


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to secure information e.g. bank account details. Data stored on the strip is scanned and

into a computer system by a reader.

MIDI (MUSICAL INSTRUMENT DIGITAL INTERFACE) A MIDI system allows you to attach a musical instrument to your computer, for example a

musical keyboard. You can then store a musical sequence on a computer and then have

the computer play it back to you.

OMR (OPTICAL MARK READER) An OMR reads marks made by pencil on a printed form into the computer. OMR systems

are suited to reading pre-printed forms and check-boxes such as National Lottery number selection sheets and multiple-choice exam papers.



questions. The student must complete the test by using a pencil to fill in each


"B", the student would have to fill in the "B Circle" in order to get the answer correct.

Hardware input device that allows a user to take an image or text and convert it into a


commonly connected to a computer USB, Firewire, Parallel, or SCSI port. Scanners


(Optical Character Recognition) software to scan in text.

A touch screen is a special type of VDU, which has a grid of light beams or fine wires criss

crossing the screen. When the screen is touched (usually to choose an on-screen option),


16

. Data stored on the strip is scanned and

A MIDI system allows you to attach a musical instrument to your computer, for example a

musical sequence on a computer and then have

An OMR reads marks made by pencil on a printed form into the computer. OMR systems

tional Lottery number



questions. The student must complete the test by using a pencil to fill in each


correct.

Hardware input device that allows a user to take an image or text and convert it into a


Scanners are now


, which has a grid of light beams or fine wires criss-

screen option),



the computer senses where you have pressed. Due to the vast amount of information they

can store, touch screen operated computers are generally used in the provision of public

information and are found in places such as airports.

12. VIDEO DIGITISER A video digitizer takes an image from a video camera or television and converts it so that

it can be used by, and stored on, a computer. Video sequences captured using a video

digitizer is often used in multimedia presentations.

13. VOICE RECOGNITION SYSTEM

A microphone is used with a voice recognition system. This can be used with a word

processing program to enter text. It can also be used as part of security systems - only certain digitally stored voices have access.

TEXT INPUT DEVICES • Chorded keyboard ,GKOS keyboard ,Keyer ,Telegraph key

(~20 WPMMorse code)

• Vibroplex (30–80 WPM Morse) ,Keyboard, Typing ,Computer keyboard

• Handwriting recognition ,Optical character recognition ,Speech recognition

POINTING DEVICES

• Light pen,Light gun,Cyberglove ,Touch screen ,Head

pointer ,Eye gaze/eye tracking

• Computer mouse ,Trackball ,Touchpad ,Pointing stick ,Graphics tablet (or digitizing tablet) ,Stylus

GAMING DEVICES

• paddle, Power Pad, Joystick ,Gamepad (or joypad)

IMAGE, VIDEO INPUT DEVICES

• Digital camcorder ,Webcam, Digital video recorder,Image scanner

• 3D scanner ,Digital camera

AUDIO INPUT DEVICES

• Microphone (see also speech recognition) ,Digital audio recorder ,Digital dictaphone

OUTPUT DEVICES

1. LOUD SPEAKER Allows a user to hear sounds and music from the computer provided the system has

installed a sound card.

2. MODEM

An Input/ Output electronic device with circuits which changes data to be transmitted

from its machine form (digital form) into a form suitable for transmission over the

telephone line (analogue form). At the receiving end it converts data vice-versa. It is

only necessary when one needs to communicate information over a long distance

and when connected to the internet.

3. HEADPHONES


Headphones give sound output from the computer.

except they are worn on the ears so only one person can hear the output at a time

4. PLOTTERS

A plotter can be used to

They are usually used for Computer Aided Design (

Manufacture (CAM) applications such as

Plotters:

How it works: • A drum plotterthe surface of a sheet of paper.

• One high precision motor moves the pen from side to side.

• Another high precision motor moves the paperbackwards and forwards.

• An electromagnet lifts and drops different coloured

ink pens onto the paper to draw lines.

• A flat• pen in the X direction and one to move it in the Y direction.

• The paper does not move.

Suitable uses: • Plotters are restricted to line drawing and can only create a solid region of colour by drawing a number of close, regular lines.

• Plotters are often used in science and engineering applications for drawing building

Advantages: • They are

standard printers.


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Headphones give sound output from the computer. They are similar to speakers,


A plotter can be used to produce high quality, accurate, A3 size or bigger drawings.

They are usually used for Computer Aided Design (CAD) and Computer Aided

Manufacture (CAM) applications such as printing out plans for houses or car parts.

drum plotter prints by moving a pen sideways over the surface of a sheet of paper.

One high precision motor moves the pen from side to side.

Another high precision motor moves the paper backwards and forwards.

An electromagnet lifts and drops different coloured

ink pens onto the paper to draw lines.

flat-bed plotter uses two high precision motors, one to move the

pen in the X direction and one to move it in the Y direction.

paper does not move.

Plotters are restricted to line drawing and can only create a solid region of colour by drawing a number of close, regular lines.

Plotters are often used in science and engineering applications for drawing building plans, printed circuit boards and machine parts.

They are accurate and can produce far larger printoutsthan standard printers.


18

They are similar to speakers,


produce high quality, accurate, A3 size or bigger drawings.

) and Computer Aided

printing out plans for houses or car parts.

uses two high precision motors, one to move the

pen in the X direction and one to move it in the Y direction.

Plotters are restricted to line drawing and can only create a solid region of colour by drawing a number of close, regular lines.

Plotters are often used in science and engineering applications for plans, printed circuit boards and machine parts.

than



Disadvantages: • Slow and relatively expensive compared to printers.

• They cannot print raster (photographic) images.

• They can only fill solid blocks of colour using closely hatched lines.

5. SPEAKER

A speaker gives you sound output from your computer. Some speakers are built

into the computer and some are separate

6. VDU (Visual Display Unit) The VDU is output device. It displays images and text in colour or black and white as it. It displays results of processing. It is also called a monitor.

7. PRINTERS It produces output on paper i.e. hard copy or on other print-key media. The 2 types of

printers are impact and non-impact.

Impact printers The printing device being a series of pins have a direct impact on the paper. The pins

form characters on the paper by pressing a printing element and an inked ribbon

against paper. An example of such a printer is the Dot Matrix. The printers are

reasonably fast, inexpensive and can produce both text and graphics. They also

accommodate various paper sizes but are however noisy.

Non-impact printers These are quieter printers and examples include LaserJet and inkjet printers. The Laser printers are a more popular choice for business use. They use a printing technique

similar to that used in a photocopying machine. A laser beam is used to form an

image onto the paper using toner. The print quality is high. Lasers are fast, and quiet.

They print graphics but are more expensive.

The ink-jet printers are mainly colour printers which mix ink depending on the image

colour and spray it onto the paper. The toner has the 4 basic colours. They are slow, expensive and have a high print quality.

What is the difference between impact and non-impact printers?

Impact Non impact

Makes noise when printing Quiet printers

Print head makes contact with the paper No contact creates an image without

striking a ribbon against the

paper.Creates images on a surface

without contacting it.

Strike ribbon against the paper Use a laser beam which form an

image onto paper using toner

Slow printer Fast printers

Use ribbons or ink Use toner

Has too many moving parts hence

unreliable

Has fewer moving parts hence they

are reliable.

Impact printers are relatively inexpensive,

and the cost of printing is also low

because ink ribbons are inexpensive.

Very expensive computers

Give two advantages of non-impact printers over impact printers.



� Have high print quality

� They are fast and do not make noise

� They are reliable because they have less moving parts

� See above [non impact section]

Give three examples of impact printers &three examples of non-impact printers.

Impact printers Non impact printers

Dot matrix Laser

Daisy wheel printers Inkjet

Line printers LED

Chain printers Thermal

Magnetic

Electrostatic

Xerographic

NON-IMPACT PRINTERS

1 - Laser printers:

How it works: • These print individual pages and work in a similar way to photocopiers.

• A drum is charged to match the image and powdered ink (toner) sticks to the surface. The

toner is then transferred to the paper and fixed

by heat and pressure.

• A school or business printer would have a typical speed of 10 to 20 pages per minute (ppm).

Suitable uses: • Common wherever fast, high quality printing is required.

Disadvantages: • Non-colour laser printers are more expensive than ink-jet printers (but the difference is narrowing).

• Colour laser printers are considerably more expensive. (but their speed and high quality output means they are becoming more popular).

Advantages: • They are quiet and fast and produce high quality printouts. • Running cost are low because although toner cartridges are expensive to

replace, they last a long time.

Laser printer - A type of printer that utilizes a laser beam to produce an image on a drum.

The light of the laser alters the electrical charge on the drum wherever it hits. The drum is

then rolled through a reservoir of toner, which is picked up by the charged portions of the

drum. Finally, the toner is transferred to the paper through a combination of heat and

pressure.

Advantages -Monochrome or four color

-High-quality print

-Capable of printing an almost unlimited variety of fonts

-Quiet operation Disadvantages -Color laser printerstend to be about five to ten times as expensive as

monochrome

-Cannot print on multiple-copy paper



2 - Ink-jet printers:

How it works: • The print head contains tiny nozzles through which different coloured inks can be

sprayed onto the paper to form the

characters or the graphic images.

• The ink is forced out by heat or by tiny piezoelectric crystals which change shape

when an electric current is applied across

them.

Suitable uses: • A popular choice for home use where small amounts of printing are done and photographic quality colour printing is needed.

Disadvantages: • The ink cartridges can be expensive so running costs can be high. • The printing speed is slow compared to a laser printer.

Advantages: • These printers are relatively inexpensive and produce high quality black and white or photographic quality borderless colour printing.

Ink-jet printer - A type of printer that works by spraying ionized ink at a sheet of paper. Magnetized plates in the ink's path direct the ink onto the paper in the desired shapes. Ink-

jet printersare capable of producing high quality print approaching that produced by

laser printers Advantages -Inexpensive way to print full-color document

-Easily portable due to smaller mechanical parts than laser printers

-Quiet operation

Disadvantages -Slow output

-Require a special type of ink that is apt to smudge on inexpensive copier paper


3. Thermal transfer printers- A type of printer that applies heat to a ribbon and the image or

barcode is then transferred to labels or tags. This technology produces a higher quality, longer

lasting image on the tag or label.

Advantages -1 to 2 years media shelf life

-Media is not heat sensitive

-Medium to high image quality

-Wide range of available types

-Recommended for industrial use

Disadvantages -Special ribbons required

-Average operational cost


-Single-pass ribbons only

4. Direct thermal printers - A type of printer that applies heat directly to specially treated paper, labels or tags to form the image or barcode.

Advantages -No ribbon required

-Low operational cost

Disadvantages


-Short media shelf life

-Very heat sensitive media

-Limited image quality

-Limited number of available types

-Not recommended for use in industrial, outdoor, or harsh environments

-Cannot print on multiple

IMPACT PRINTERS 1 - Dot matrix printers:

How it works: The print head travels

from side to side

across the paper and is made up of

numerous pins which

are pushed out to

form the shape of

each character

The pins hit an ink ribbon against the paper so

the characters are

The paper is usually continuous with holes down each side and perforations so the

pages can be easily separated by tearing.

Because the pins make an impact against the

paper the characters can be printed through

several layers of self

produce duplicate copies.

Suitable uses: • Limited to situations where duplicate copies are needed and the quality is not too important.

• Typical uses might be in need to produced quickly and cheaply.

Disadvantages: • The printing black and white printing and can only print low resolution graphics.

• Because of the impact of the pins against the paper, these printers can be

quite noisy

Advantages: • The purchase cost is low• They can print

copies are being pri

• They are

• If several sheets of self


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Very heat sensitive media

Limited number of available types

Not recommended for use in industrial, outdoor, or harsh environments

Cannot print on multiple-copy paper

The print head travels

from side to side

across the paper and

numerous pins which

are pushed out to

form the shape of

each character

The pins hit an ink ribbon against the paper so

the characters are printed out.

The paper is usually continuous with holes down each side and perforations so the

pages can be easily separated by tearing.

Because the pins make an impact against the

paper the characters can be printed through

several layers of self-carbonating paper to

produce duplicate copies.

Limited to situations where duplicate copies are needed and the quality is not too important.

Typical uses might be in warehouses where duplicate copies of orders need to produced quickly and cheaply.

The printing quality is low - these printers produce low to medium quality black and white printing and can only print low resolution graphics.

Because of the impact of the pins against the paper, these printers can be

quite noisy.

purchase cost is low and the running costs are very low. They can print fairly quickly, particularly if you remember that multiple copies are being printed in one print run.

They are robust and can operate in harsh environments. If several sheets of self-carbonating paper are placed into the printer then


22

Limited to situations where duplicate copies are needed and the quality is

where duplicate copies of orders

these printers produce low to medium quality black and white printing and can only print low resolution graphics.

Because of the impact of the pins against the paper, these printers can be

, particularly if you remember that multiple

carbonating paper are placed into the printer then



the impact will produce duplicate copies.

Dot-matrix printer- A type of printer that produces characters and illustrations by striking pins against an ink ribbon to print closely spaced dots in the appropriate shape.

Advantages -Can print to multi-page forms-

-Moderately priced

-Multi-pass ribbons (saves money)

Disadvantages -Noisy operation

-Low-quality output

-Slow print speed

-Multi-pass ribbons (decrease in quality with each pass)

2. Daisy wheel Printers • Round disk found on older computer printers t hat extends a portion of the wheel making

contact with ink ribbon that makes contact with paper creating the character. This

procedure is repeated for each key pressed.

• Daisy Wheel printer - A printer that uses a wheel with all the characters on it to produce output. The wheel spins to the desired characterand makes an imprint, then spins to go to

the next character. It sounds like a little machine gun.

• These printersgenerally aren't used much anymore due to the decreased cost of other

printers that can produce graphics as well as text. The one good thing about a daisy-

wheel printer is that the text is generally very crisp, but even that advantage is nullified

now with laser printers that can produce very crisp characters as well.

Advantages -Best print quality of impact printers

Disadvantages -Very slow

-Only one font can be used at a time because you must change out the Daisy

Wheel to change fonts.

-Cannot print graphics

3. Chain and band printers - Uses characters on a band or chain that is moved into place

before striking the characters onto the paper.

Advantages Very fast

Disadvantages -Very loud

-Very expensive

You have been delegated the task of selecting a new printer from a range of different options currently on the market. The machine has to serve a small network of microcomputers in your office. Software used includes a word processing package, database, spreadsheet, and presentation packages. Assuming that cost is not a major constraint, list 10 features of the printers, which you would investigate in your evaluation.

1. Print quality, for example the print from dot matrix printers varies with the number of pins and even the best are inferior to laser printers.

2. Character formation, whether made from dots as in matrix printer, or full characters as with

daisywheel or laser printer

3. Multi-part, i.e. whether several copies can be printed at once, as with an impact printer.

4. Fonts or type style; early computer users were satisfied with any quality whatsoever, but the

advances into areas such as word processing and desk top publishing have stimulated a

demand for varying type faces or fonts within the same document



5. Letter quality, whether the quality is equivalent or superior to that of a good typewriter and so acceptable for the word processing of mail. Some printers have a choice of two print

modes, draft quality and letter quality.

6. Speed, in terms of characters per second.

7. Graphics capabilities. 8. Flexibility, for example is it suitable for one task only, such as good letter quality but not

graphics, as with daisywheel printers, or good graphics but slow speed and indifferent

letter quality, as with some dot matrix printers.

9. Sheet feeding, in terms of single sheets, friction feed or sprocket feed.

10. Capital cost or what it costs to buy. 11. Running cost or what it costs in ribbons, print toner, special stationery & maintenance.

12. Compatibility with standard packages; many programs support a range of printers by generating the correct control characters for fonts, features like italics and underline, and

for graphics.

13. Robustness; some very cheap printers are ideal at home but would not last very long in an

office.

14. Reputation of the manufacturer as a supplier of printers. STORAGE DEVICES

These are devices that store information permanently. They are also known as Auxiliary

storage devices or Secondary storage devices. They include:-

a) THE HARD DISK A fixed device for storing information within the computer system unit. The disk is not

moveable and is also referred to as the C:\ drive. The amount of disk space a computer

has determines the power of a computer. It provides fast access known as Random

access and has high-speed storage.

b) FLOPPY DISKETTE An external form of storage used for back up. Information can be deleted and rewritten

and re-saved. The storage device is common for microcomputers. The disks are either High

density or double density disks because data is stored more densely/ compactly than on

regular density disks. Common size of disk is 31/2inches. ADVANTAGES OF FLOPPY DISKETTES

1. They are cheaper than Hard disks and CD-ROMS 2. They are portable hence used to transfer data or information from one computer to

another 3. They offer direct access and they are faster than magnetic tapes

DISADVANTAGES OF FLOPPY DISKETTES

1. They are prone to viruses

2. They are difficult to handle

3. They can easily be corrupted

4. They have a relatively short life span

5. They hold relatively small amounts of data

6. They are not always 100% reliable

CARE AND HANDLING OF A FLOPPY DISKETTE

1. Don’t put the diskette near any magnetic field.

2. Don’t put the diskette near any electronic motor.

3. Don’t expose the diskette to direct sunshine or heat.

4. Store the diskette in a cool dry dust-free environment.

5. Don’t spill liquid onto the diskette.

6. Don’t use any diskette which has had liquids spilled on it.

7. Don’t bend or fold a diskette. 8. Don’t staple labels onto the diskette.



9. Use a soft pencil or felt-tip pen when writing on diskette labels, as the pressure of a

ballpoint may leave indentations on the magnetic surface.

10. Don’t touch the magnetic surface (the black plastic like plate) of the disk, as your

fingerprints may hinder the drive in reading from and writing to the disk .

c) CATRIDGE TAPE Data is recorded in the form of magnetized spots on an iron oxide coating of a plastic

tape. Gaps are used to separate individual data records. The tape is similar to audiotapes.

Access of information from the tape is in sequential form and thus slow.

d) CD-ROM (Compact Disk Read Only Memory) Beams of laser light are used to write on optical disks by magnetic means. After writing, the disk can only be read from and not written to. Access to information is direct and very fast.

e) WORM (Write Once, Read Many) WORM Disks allow microcomputers with the proper drive known as a CD Rewriters (or a

burner) to record own data on a blank CD. Once the recording is done, the disk can only

be read from and cannot be rewritten.

Erasable optical disks are also available and are known as EPROM. The major advantage

of optical disks is their storage capacity. The information on one optical requires multiple

floppies.

f) DVD (Digital Versatile Disks) A form of optical disks similar to CD ROMS but has much more storage

capacities of up to 3.9GB. They support audio and video as well as

data on the same disk.

g) ZIP DISKS These are high capacity removable diskettes. They have gained favor for back-up

purposes. Some zip disks use magnetic technology and others use laser. They have a

capacity of about 100MB.

Storage devices differ in terms of capacity, cost and access methods. For any device to

be used there is a need for the device drive on the computer e.g. A floppy disk drive. DISK CARE

1) Do not expose them to sun or a hot environment.

2) Keep them away from moisture or water.

3) Keep them away from magnetic fields i.e. Phones, tops of some monitors, magnetized

items etc..

4) Do not touch the actual tape.

5) Keep them away from dust.

6) Do not place heavy objects on them.

7) Write on a floppy disk label only with a felt-tip pen, or write before sticking the label

8) Avoid using rubber bands, paper clips and erasers on floppy disks

HARDWARE CARE 1) Make sure there is enough space for the machines to breathe. (Fresh air is necessary

to make the fan keep the electronics cool).

2) Do not block air vents with books.

3) Keep the computer dry.

4) House the machine in a dust free environment e.g. 1ST floor carpeted-room (Carpets

suck dust) and, use a vacuum cleaner to clean the carpet. (Dust is the biggest killer of

hard drives).

5) Do not expose the machine to extreme temperatures.

6) Properly shut down the machine before turn-off. 7) Pull the plug out of socket when there is thunder and lightning.



8) Do not move the system when the computer is on. The hard drive can be damaged.

9) Use of UPS- Uninterruptible Power Supply in case of power failures,

10) Use of Surge Protectors against too high voltages. DEFINE HARDWARE & GIVE EXAMPLES.

� Hardware comprises all of the physical parts of a computer, as distinguished from the data

it contains or operates on, and the software that provides instructions for the hardware to

accomplish tasks.

DEFINE SOFTWARE & GIVE EXAMPLES. � Computer software (or simply software) refers to one or more computer programs and

data held in the storage of a computer for some purpose. � Program software performs the function of the program it implements, either by directly

providing instructions to the computer hardware or by serving as input to another piece of

software.

CLASSIFICATION OF COMPUTERS

Computers differ based on their data processing abilities. They are classified according to purpose,

data handling and functionality.

• According to purpose, computers are either general purpose or specific purpose.

� General purpose computers are designed to perform a range of tasks. They have

the ability to store numerous programs, but lack in speed and efficiency.

� Specific purpose computers are designed to handle a specific problem or to

perform a specific task. A set of instructions is built into the machine.

• According to data handling, computers are analog, digital or hybrid.

� ANALOG COMPUTERSwork on the principle of measuring, in which the

measurements obtained are translated into data. Modern analog computers

usually employ electrical parameters, such as voltages, resistances or currents, to

represent the quantities being manipulated. Such computers do not deal directly

with the numbers. They measure continuous physical magnitudes.

� DIGITAL COMPUTERSare those that operate with information, numerical or

otherwise, represented in a digital form. Such computers process data into a

digital value (in 0s and 1s). They give the results with more accuracy and at a

faster rate. Hybrid computers incorporate the measuring feature of an analog

computer and counting feature of a digital computer. For computational

purposes, these computers use analog components and for storage, digital

memories are used.

• According to functionality, computers are classified as :

� Analog Computer

An analog computeris a form of computer that uses continuous physical

phenomena such as electrical, mechanical, or hydraulic quantities to model the

problem being solved

� Digital Computer

A computer that performs calculations and logical operations with quantities

represented as digits, usually in the binary number system



� Hybrid Computer (Analog + Digital)

A combination of computers those are capable of inputting and outputting in

both digital and analog signals. A hybrid computer system setup offers a cost

effective method of performing complex simulations.

Classification on the basis of Size

Major classes or categories of computers

Supercomputers � Describes a category of extremely powerful computers specifically designed for high-speed

numeric computation.

� The computers can process hundreds of millions of instructions per second.

� High capacity computers capable of executing instructions faster than main frame & are

extremely expensive.

� The speed of executing these instructions generates extreme heat, and therefore the

computers require special cooling system to operate.

� Uses include weather forecasting, scientific and mathematical research, and design of high-

speed aircraft and space exploration.

Mainframes � Are large, powerful computers that are physically larger than micros and minis and usually

have one or more central processors with faster instruction processing speeds?

� They typically process hundreds of millions of instructions per second.

� Mainframes have large primary storage capacities.

� Many mainframe models have the ability to service hundreds of users at once.

� Some commercial organizations require large amounts of data to be processed in the list

possible time.

� Mainframes allow one to perform such functions

� Uses of mainframes include: data warehousing, commercial airline ticketing & reservations,

government record keeping & financial servicing

� Application categories: Host computers, Database servers, and Transaction processors.

Minicomputers � Are larger and more powerful than most microcomputers but are smaller and less powerful

than most mainframe computer systems.

� Serve in industrial process-control manufacturing plant computers and play a major role in

CAM.

� Also take the form of powerful technical workstations for CAD applications.

� Often used as front-end processors/computers to help mainframe computers control data

communications networks with large numbers of data entry terminals.

� Also used as powerful Network servers to help manage large interconnected LANs that tie

together many workstations

� Downsizing is a term that was commonly used in the early nineties when smaller computers, capable of much of the functions of mainframes, began capturing the computer market.

� Minicomputers are suitable for mid-sized companies that require the computing power of

mainframes to be efficient and at the same time be cost effective.

� Users of mini-computers would be smaller banks & financial institutions, supermarket chains and

departmental stores.

� Application categories: Network servers, and Application systems

Microcomputers � We refer to a microcomputer as a personal computer or PC.

� Microcomputers categorized by size include: Desktops, Laptops for example.

� Most microcomputers are single user computers.

� The late nineties have seen a huge influx of microcomputers whose sole aim was to provide

affordable computing power to the general public.



� They are now used as Network servers. The demand for microcomputers and the changes in

microchip technology have produced cheaper computers that are affordable to students

and the general public.

� Can support CAD.

� Users of microcomputers range from students, who use them for word processing, to a

salesperson. Who depend on the microcomputer for information?

� Application categories: PCs, Network servers. � Network servers are powerful microcomputers that controls & coordinates communication &

resource sharing in LANs of interconnected PCs & other devices.

The main differences among the above computer types are in: • Processing speed, • Memory capacity

• Number and capabilities or peripheral devices that can be attached to the computer

• Usage.

COMPUTER APPLICATIONS

a) Business- for administration, payroll and accounting.

b) Government- keeping database records. c) Education- Record keeping, accounting and training in the classroom.

d) Health- Record keeping, life-support systems.

e) Sport- fitness monitoring.

f) Art and Design- desktop Publishing, technical graphics, Computer Aided Design.

g) Homes- PCs for home accounts, games, e-mail, online shopping, home education

etc.

h) Banks- Record keeping and updating, on-line Automated Teller Machines (ATMs).

i) Supermarkets- Electronic point Of Sale Machines (EPOS) – tills.

FACTORS TO CONSIDER WHEN YOU WANT TO PURCHASE OR BUYA COMPUTER

1. COST; how much can I afford to pay for a computer? Prices of personal computers

range from a few hundred to thousands of dollars. Faster and more feature-rich PCs

are usually more expensive.

2. AREA OF USE; where will my new PC be used? If you will be using it only in your home or

office, a desktop computer will be suitable. However, if you will need to take it with you, you should consider purchasing a laptop (notebook) computer.

3. APPLICATIONS PACKAGES; Which application packages will I run on my computer? Make a list of applications for which you plan to use your PC. For example, will you use

your PC to prepare letters and reports? Analyze numeric and financial data? Prepare

visual presentations? Access the Internet? Listen to music? Create and work with

graphics?

4. DURATION; How long will I keep this computer?Try to estimate the length of time

(years) you will use your computerbefore BUYING the next one. If you expect use your PC for several years or if you think you may later want to add new applications,

CONSIDER one that is expandable, so you can add new components, such as a

modem, printer, or add-on boards. Make sure the PC has expansion slots so you can

connect these devices to your PC.

5. MANUFACTURER AND SELLER REPUTATION. Check out the manufacturers and seller’s reputations.Talk with friends, co-workers, classmates, teachers, and others about their

PCs. Ask about the performance of their PCs and get recommendations from persons

you trust. Eventually you may need to have your PC serviced. Ideally, the vendor has a

service department that can repair your PC. If not, you may need to locate a third-

party to provide this service. Reputable computer manufactures include:



1. Hewlett-Packard 2. Apple 3. Sun Microsystems 4. Dell 5. Panasonic 6.Sony 7.Toshiba

8. Shuttle 9. IBM 10. Samsung Electronics 11. Hitachi 12. Fujitsu Siemens 6. WARRANTIES & GUARANTEES

7. PC ARCHITECTURE. PC architecture refers to the design and construction of the PC and its system unit, and not all architectures are the same. For example, the architecture of

an Apple Macintosh differs from that of an IBM or compatible PC. Therefore, software

written for an Apple Macintosh PC may not run on an IBM or IBM-compatible PC.

Although some users prefer a Macintosh PC, more software is available for IBM and

IBM-compatible PCs.

8. MICROPROCESSOR SPEED. Selecting the right microprocessor is extremely important. Processing speed, measured in megahertz (MHz) or gigahertz (GHz), is probably the

first consideration. The higher the number of MHz or GHz, the faster the processor will

manipulate data. If speed is important, consider choosing a microprocessor with a

speed of 2 GHz or more. PCs containing microprocessors with speeds up to 10 GHz

and higher are available.

9. MAIN MEMORY (RAM). Main memory (RAM) is needed for the temporary storage of

programs and data while the data is being processed. Some application software

requires a considerable amount of RAM to function properly, and newer software

versions usually require more RAM than older versions. Typical PCs now come with 2

gigabytes (GB), 5GB, or more of RAM. Make certain the PC has sufficient RAM to run

the software you will be using.

10. SECONDARY STORAGE (ROM). What type(s) and amounts of secondary storage are

you likely to need? Typical computers come with a floppy disk drive, cd drive, USB

port/ drive and a hard disk drive already installed. A hard disk drive contains one or

more rigid storage platters and provides for the permanent storage of considerably

more data. However, the disk itself cannot be removed from the drive.

The STORAGE CAPACITY of a hard disk is an important consideration because it is used

to store all system and application software. Typical hard disk capacities are 100, 200,

500GB or 2TB and more. Be certain the PC you are considering has sufficient secondary capacity for your needs

CD-ROM or DVD drives provide high storage capacities. Most software publishers store

their programs on CD-ROM or DVDs because of the high capacity and because

DVD/CD-ROMs operate faster than floppy disks.

If you will use your PC to play movies, your purchase should include a DVD (digital

video disk) drive. If you will work with large files, consider purchasing a computer that

includes a DVD/CD-RW drive. A DVD/CD-RW disk is a reusable high-capacity disk that

allows you to store huge amounts of data and to erase data no longer needed.

11. PORTS.The number of ports (slots) available inside the system unit determines the

number of add-on boards that can be installed inside the system unit. For example,

you cannot connect a printer to your computer unless youcomputerr is equipped with

an appropriate port (slot). Be sure the PC contains the necessary slots for the add-on

boards and peripheral devices you will be using with your computer.

12. INPUT DEVICES.Typical input devices are a keyboard and a mouse, although other

kinds of input devices are available. Most keyboards and mice operate similarly.

However, there are slight differences in how each "feels" to the user. Before buying a

PC, you may want to test the keyboard and mouse for comfort and ease of use. Some

sellers will allow you to exchange the keyboard or mouse that comes with the

computerfor a different one.



13. OUTPUT DEVICES. Output devices produce output in either soft copy or hard copy form. Most PCs come with a monitor (for soft copy output), but you may have to

purchase a hard copy device, such as a printer, separately.

14. MONITORS. There are wide differences among PC monitors, with resolution being

perhaps the most important variable.

Resolution refers to the clarity of the text and images being displayed. Before making

a purchase, carefully evaluate the monitor’s resolution. Many vendors allow you to

choose from monitors with varying resolutions. A resolution of 1,024 by 1,024 is

considered high-resolution, in which text and images display exceptionally clearly.

High-resolution monitors are typically more expensive.

Monitor size is another important consideration. Viewing areas range from 15 diagonal

inches to 21 inches and higher. Larger monitors are usually more expensive, but may

be worth the extra cost. For example, an individual with weak vision may prefer a

larger monitor. If your desktop space is limited, consider purchasing a flat-panel

monitor, which occupies less space. Flat-panels are more expensive than standard

monitors, however.

NECESSARY CONDITIONS FOR AN IDEAL COMPUTER ROOM ENVIRONMENT.

1. Cleanliness [books, manuals not encouraged] because they bring dust & caught fire

easily.

2. Air conditioners, which control the room and dehumidates it.

3. It should be dust free; dust is the biggest “killer” of hard drives.

4. No carpets, they caught fire more easily.

5. You are not allowed to eat, smoke or drink in the computer room.

6. No magnetic material should be in the computer room.

7. The computer room should be located in such a way that computers are not

exposed to direct sunlight or hot environments, use curtains if otherwise.

8. The computer room should be fitted with burglar bars, alarm systems, or guarded 24hours to ensure security.

9. The computer room should have surge protectors or suppressors to guard against

electrical faults and high voltages.

10. The computer room should have UPS [uninterrupted power supply] in case of power

failures, which may be fatal.

11. Computer room should be well ventilated, to allow for air circulation,

12. Foreign media, such as floppy diskettes, flash disks should not be allowed in order to

minimize virus spread.

13. Always switch off machines if not in use.

14. Avoid overloading circuits. 15. All cabling and wiring should not be exposed; it should be covered and should not

criss cross the room.

16. Leave enough space between computers and the walls.

17. Do not use chalk the computer room , dry wipe markers are encouraged.



DUTIES & RESPONSIBILITIES OF COMPUTER PERSONNEL

ROLES OF A Database Administrator (DBA) a) The design of the database

b) After the initial design, the DBA must monitor the performance of the database, and if

problems surface (such as a particular report taking an unacceptably long time to

produce), appropriate changes must be made to the database structure.

c) Keeping users informed of changes in the database structure that will affect them; for

example, if the size or format of a particular field is altered or additional fields added

d) Maintenance of the data dictionary for the database, and responsibility for

establishing conventions for naming tables, columns, indexes 7 so on.

e) Implementing access privileges for all users of the database; that is, specifying which items can be accessed and / or changed by each user.

f) Allocating passwords to each user.

g) Providing training to users in how to access and use the database.

h) Manage the organization of

i. -data resources

ii. -database plans

iii. -design

iv. -operations

v. -training

vi. -user support

vii. -security & Maintenance

i) Maintain data consistency and security

j) Approve access to data stored

k) Approve access procedures

l) ABILITY to delete, add, modify –existing data must be tightly controlled.

1. COMPUTER SUPPORT SPECIALISTSprovide technical assistance, support, and advice to customers and other users. This occupational group includes technical support

specialists and help-desk technicians. These troubleshooters interpret problems and

provide technical support for hardware, software, and SYSTEMS. They answer

telephone calls, analyze problems by using automated diagnostic programs, and resolve recurring difficulties. Support specialists may work either within a company

that uses computer SYSTEMSor directly for a computer hardware or software vendor.

Increasingly, these specialists work for help-desk or support services firms, for which

they provide computer support to clients on a contract basis.

2. TECHNICAL SUPPORT SPECIALISTSanswer telephone calls from their organizations’

computer users and may run automatic diagnostics programs to resolve problems.

Working on monitors, keyboards, printers, and mice, they install, modify, clean, and

repair computer hardware and software. They also may write training manuals and

train computer users in how to use new computer hardware and software. In

addition, technical support specialists oversee the daily performance of their

company’s computer SYSTEMSand evaluate software programs with regard to their

usefulness.

3. HELP-DESK TECHNICIANSassist computer users with the inevitable hardware and

software questions that are not addressed in a product’s instruction manual. Help-

desk technicians field telephone calls and e-mail messages from customers who are

seeking guidance on technical problems. In responding to these requests for

guidance, help-desk technicians must listen carefully to the customer, ask questions

to diagnose the nature of the problem, and then patiently walk the customer through

the problem-solving steps.Help-desk technicians deal directly with customer issues,

and companies value them as a source of feedback on their products. These



technicians are consulted for information about what gives customers the most

trouble, as well as other customer concerns. Most computer support specialists start

out at the help desk.

4. NETWORKADMINISTRATORS AND COMPUTERSYSTEMS ADMINISTRATORSdesign, install, and support an organization’s local-area network (LAN), wide-area network (WAN),

network segment, Internet, or intranet system. They provide day-to-day onsite

administrative support for software users in a variety of work environments, including

professional offices, small businesses, government, and large corporations. They

maintain network hardware and software, analyze problems, and monitor the

network to ensure its availability to system users. These workers gather data to identify

customer needs and then use the information to identify, interpret, and evaluate system and network requirements. Administrators also may plan, coordinate, and

implement network security measures.

5. SYSTEMSADMINISTRATORSare the information technology employees responsible for

the efficient use of networks by organizations. They ensure that the design of an

organization’s computer site allows all of the components, including computers, the

network, and software, to fit together and work properly. Furthermore, they monitor

and adjust the performance of existing networks and continually survey the current

computer site to determine future network needs. Administrators also troubleshoot

problems reported by users and by automated network monitoring SYSTEMSand

make recommendations for enhancements in the implementation of future servers

and networks.

6. In some organizations, COMPUTER SECURITY SPECIALISTSmay plan, coordinate, and

implement the organization’s information security. These workers may be called upon

to educate users about computer security, install security software, monitor the

network for security breaches, respond to cyber attacks, and, in some cases, gather

data and evidence to be used in prosecuting cyber crime. The responsibilities of

computer security specialists has increased in recent years as there has been a large

increase in the number of cyber attacks on data and networks. This and other

growing specialty occupations reflect an increasing emphasis on client-server applications, the expansion of Internet and intranet applications, and the demand

for more end-user support.

7. COMPUTER PROGRAMMERSwrite, test, and maintain the detailed instructions, called

programs that computers must follow to perform their functions. Programmers also

conceive, design, and test logical structures for solving problems by COMPUTER.

Programmers write programs according to the specifications determined primarily by

COMPUTER software engineers and systems analysts.After the design process is

complete, it is the job of the Programmer to convert that design into a logical series of

instructions that the COMPUTER can follow. The Programmer codesthese instructions

in a conventional programming language such as COBOL; an artificial intelligence

language such as Prolog; or one of the most advanced object-oriented languages,

such as Java, C++, or ACTOR. Different programming languages are used depending

on the purpose of the program.

8. DATA PREPARATION STAFF Are those people responsible for the translation of data into machine readable form.

9. COMPUTER SCIENTISTSwork as theorists, researchers, or inventors. Their jobs are distinguished by the higher level of theoretical expertise and innovation they apply to

complex problems and the creation or application of new technology. Those employed by academic institutions work in areas ranging from complexity theory to



hardware to programming-language design. Some work on multidisciplinary projects,

such as developing and advancing uses of virtual reality, extending human-computer

interaction, or designing robots. Their counterparts in private industry work in areas

such as applying theory; developing specialized languages or information

technologies; or designing programming tools, knowledge-based systems, or even

computer games.

10. DATA ENTRY AND INFORMATIONPROCESSING WORKERShelp ensure the smooth and

efficient handling of information. By keying in text, entering data into a computer,

operating a variety of office machines, and performing other clerical duties, these

workers help organizations keep up with the rapid changes that are characteristic of

today’s “Information Age.” In addition to the job titles discussed below—such as word processors, typists, and data entry keyers—data entry and information processing

workers are known by various other titles, including electronic data processors,

keypunch technicians, and transcribers.

11. DATA ENTRY KEYERSusually input lists of items, numbers, or other data into computers

or complete forms that appear on a computer screen. They also may manipulate

existing data, edit current information, or proofread new entries into a database for

accuracy. Some examples ofdata sources include customers’ personal information,

medical records, and membership lists. Usually, this information is used internally by a

company and may be reformatted before other departments or customers utilize it.

12. DATA CONTROL is our customer services area for all agencies that utilize Information

Technology's services for reports of any kind. This section receives and distributes all

incoming data for appropriate processing; they set up batch reporting for all

agencies and submit schedules for processing to Computer Operations. After

processing has occurred, they check and distribute reports to all customers. This area

interacts with agency customers and other Information Technology areas to resolve

processing problems. This area maintains all tape media including updating the tape

inventory system and it also has responsibility for off site tape storage. Updating the

Information Technology web page using HTML and other software tools is done by

Data control. Data control is also responsible for all data preparation prior to centralized processing. Assisting the paper peripheral area and reception area are

also functions of this section.

13. COMPUTER OPERATORSare responsible for the operation of all enterprise, Unix, NT, and Windows 2000 servers, Unix and personal computers that are utilized to service the

County's customer base. This area receives all hardware service calls, assists in

terminal and communication equipment installation and software/hardware trouble

diagnosis. Processing of all batch production work as well as all paper peripheral

processing are also functions of Computer Operations.

14. NETWOR MANAGER, managing a network infrastructure and providing technical

support and advice to the client organisations. This type of post would usually require

the postholder to be educated to degree level or equivalent standard and to have

considerable experience of network management and protocols including TCP/IP.

Additional requirements might include experience in the management of industry

standard network operating systems such as Novell NetWare, UNIX and MS Windows

NT & 2000 server, together with skills in the use of database applications, such as

Oracle, email server applications such as MS Exchange 5.5 or 2000 and PC

applications such as MS Office & XP.

Research – important area

1. FIND OUT THE DUTIES AND RESPONSIBILITIES OF THE FOLLOWING

a) Computer programmer b) System analyst

c) System administrator d) Computer librarian



e) Data preparation staff f) Network administrator g) Data control staff h) IT manager

i) Data processing manager j) Computer operators k) Data capturing clerk

2. Write notes on

DATA PROCESSING METHODS a) Manual data processing

b) Mechanical data processing

c) Electronic data processing

d) Automatic data processing

e) Online data processing

f) Distributed data processing

g) Centralized data processing

h) Transaction processing

i) Decentralized data processing

j) Time sharing data processing

k) Batch or offline data processing

3. Advantages and disadvantages of computers Ask if you are not sure

DATA SECURITY /PROTECTION � Data Security/Protection

� Refers to keeping data safe from various hazards or dangers like natural hazards,

deliberate corruption or destruction of software & hardware by malicious or terrorist

acts, illegal access to data by hackers [people who break into the system] &

accidental destruction of data by hardware or software failure [operator error].

MEASURES TO ENSURE DATA SECURITY 1. Data Encryption/Decryption- Data is coded before transmission over a WAN & decrypted

only if you have the key & code to decrypt the data on the receiving end. The process of

transforming a message in ordinary language i.e. plain text to produce what is called cipher text which is then send along a communication line/link. The receiving computer

uses another transformation to decode the message.

a. Definitions of decryption on the Web:

• The process of converting encrypted content back into its original form, often the process of converting cipher text to plaintext. Decryption is the opposite of encryption.

• Definitions of encryption on the Web:

• Any procedure used in cryptography to convert plaintext into cipher text in order to prevent

anyone except the intended recipient from reading that data. There are many types of data

encryption, and they are the basis of network security. Common types include Data Encryption Standard and public-key encryption.

• Definitions of cipher text on the Web:

• Data that has been transformed by encryption so that its semantic information content (ie, its meaning) is no longer intelligible or directly available.

2. Firewall- a firewall is a software program designed to prevent unauthorized access to a PC or

network through a connection to the Internet. It works by monitoring all data sent to and from the

PC and comparing the data with a set of user-defined security criteria. Any data that does not

meet that criteria is blocked. Firewalls also process encrypted data. They verify the validity of the

user. User would require access to the firewall before they can transmit data. Latest firewalls also

have the ability to detect virus software in packets of data that is sent through the network.

Firewalls disallow data transmission if it detects strains of virus on the data being transmitted.

3. Usernames & Passwords-Passwords restrict only authorized personnel/users to have access to the data or computer rooms [cards]. Passwords bring in an aspect of

accountability, if a file is deleted, the person with the password will be reported as the culprit through logging. Passwords can be forgotten. Widely used by

companies to protect their equipment & data

4. Authorized entry to computer installations-Most installations have card readers,

voice recognition systems or keypads on the doors that prohibit entry to

unauthorized personnel.

5. Backing-up files on external disks periodically.

6. Keeping backup copies of files in a different location and making about 3

generations of backup.



7. Saving work frequently

8. Avoiding viruses.

9. Restricting access to the computer room. Access could be only through codes,

voice recognition etc.

10. Installing fire alarms.

11. Lining computer rooms with fire resistant material.

12. Placing the computer room in upper floors of a building to avoid burglaries.

13. Having a security guard 24 hours a day. Summary - Keeping data secure Measures that can be taken to keep data safe include:

• Making regular back-ups of files. (Back up copies should be stored safely in fireproof safes or in another building.)

• Protecting yourself against viruses by running anti-virus software. • Using a system of passwords so that access to data is restricted.

• Safe storage of important files stored on removable disks - eg locked away in a fireproof

and waterproof safe.

• Allowing only authorized staff into certain computer areas, eg by controlling entry to these areas by means of ID cards or magnetic swipe cards.

• Always logging off or turning terminals off and if possible locking them.

• Avoiding accidentally deletion of files by write-protecting disks.

• Using data encryption techniques to code data so that it makes no apparent sense

� BACK UP � Copying or saving data to a different location. One can restore the backup copy

if data is lost or damaged.

� To create a copy of a disk’s contents on another location for safe keeping. Since

hard drives are not infallible, it is recommended that you backup its contents

regularly. DISASTER PLANNING

� Many companies have comprehensive emergency plans so that even after suffering a severe:

� Bomb � Fire damage � Natural disaster, the company can be up and running within a day or two.

� A disaster recovery service/programme provides for example

� Office space � Computer facilities � Phones � Desks, at an emergency BACKUP site.

� A completely up to date copy of the company Database may be permanently maintained at

this site with all transactions being transmitted to this remote site updating the database, copying etc.

� The data should be backed up/stored to one or more media to ensure recovery in case of

disaster.

� The back up procedures and media should be tested periodically to assess their effectiveness.

Definitions of disaster plan on the Web:

• The documented policies and procedures intended to either prevent damage, minimize damage, or recover from damage to record materials.

Definitions of disaster recovery plan on the Web:

• The document that defines the resources, actions, tasks and data required to manage the business recovery process in the event of a business interruption. The plan is designed to

assist in restoring the business process within the stated disaster recovery goals.

• Part of an overall contingency plan. The plan for a process whereby an enterprise would restore any loss of data in the event of fire, vandalism, natural disaster, or system failure.



MAJOR THREATS TO INFORMATION SYSTEMS/COMPUTERS Key threats to data security

• Data can be lost or damaged during a system crash - especially one affecting the hard disk.

• Data can become corrupt as a result of faulty disks or disk drives, or power failures. • Data can be lost by accidentally deleting or overwriting files. • Data can be lost or become corrupted by computer viruses. • Data can be hacked into by unauthorized users and deleted or altered. • Data can be destroyed by terrorist activities, war, bombs and fire.

• Data can be deleted or altered by unpleasant employees wishing to make money or seek revenge on their employers.

Explain 5 major threats to information systems; for each threat describe its impact and preventative measure you would adopt to prevent it. [15].

THREAT IMPACT CONTROL Hardware failure • You are grounded

• You cannot access the

system

• Data is incorrectly/

incompletely processed

• Have spares in the

warehouse.

• Do regular servicing

• Have a disaster plan

• Run hardware diagnostics

frequently

Electrical faults • Loss of data

• Disk crushes

• Damage to hardware

• Have standby generators

• Install UPS [uninterrupted

power supply]

• Install Surge suppressors/

protectors

Software failures • Operations are grounded

• Buy software from

reputable vendors.

• Do regular back ups

• Software diagnostics

Natural disasters/ physical threats • Absolute destruction • Relocate backups to

other areas free from

disasters

Viruses • Deletion & corruption of files

• Reformatting of documents

• System may fail to work

• Install a reliable anti-virus

software

• Never download

unknown e-mail

attachments

• Scan unknown diskettes

Hackers, Computer crime • Security is breached

• Security is bypassed

• Destruction of files

• Data is stolen

• Change passwords

regularly

• Employ a security guard

• Install a firewall

• Prevent unauthorized

access to computer facilities.

War and Terrorist activity

Human error



Definitions of computer abuse on the Web:

• The willful or negligent unauthorized activity that affects the availability, confidentiality, or integrity of computer resources. Computer abuse includes fraud, embezzlement, theft,

malicious damage, unauthorized use, denial of service, and misappropriation

Definitions of hacking on the Web:

• Unauthorized use, or attempts to circumvent or bypass the security mechanisms of an information system or network. Hacking means illegally accessing other people's computer

systems for destroying, disrupting or carrying out illegal activities on the network or

computer systems.

DATA INTEGRITY/RELIABILITY • Refers to the correctness AND The accuracy of data after being transmitted or processed

• Data in the computer system may become incorrect, corrupted or of poor quality in many

different ways & at any stage during data processing.

� Consequences of system failure:

� Loss of business due downtime

� Delays

� Air traffic control system could well have catastrophic results

COMPUTER CRIME/FRAUD

� Computer crimes are criminal activities, which involve the use of information technology to

gain an illegal or an unauthorized access to a computer system with intent of damaging,

deleting or altering computer data. Computer crimes also include the activities such as

electronic frauds, misuse of devices, identity theft and data as well as system interference.

Computer crimes may not necessarily involve damage to physical property. They rather include the manipulation of confidential data and critical information. Computer crimes

involve activities of software theft, wherein the privacy of the users is hampered. These

criminal activities involve the breach of human and information privacy, as also the theft

and illegal alteration of system critical information. The different types of computer crimes

have necessitated the introduction and use of newer and more effective security

measures.

� Computer Fraud/Crime � Criminal actions accomplished through the use of computer systems, especially

with the intent to defraud, destroy, damage, or make unauthorized use of

computer resources.

� E.g. improper transfer of funds from one account to another

TYPES OF COMPUTER CRIME/FRAUD

a) Intellectual Crime – cracking into a computer system for the purpose of

transferring or obtaining funds is a typical e.g.

b) Destruction of property – destroying a computer property

c) Theft – Software piracy which is unauthorized copying of software. Hardware & software being taken away without the knowledge/consent of its owners.

d) Fraud achieved by the manipulation of computer records.

e) * Spamming wherever outlawed completely or where regulations controlling it are

violated.

f) * Deliberate circumvention of computersecurity systems. g) * Unauthorized access to or modification of programs (see software cracking and

hacking) & data.

h) * Intellectual property theft, including software piracy.

i) * Industrial espionage by means of access to or theft of computer materials.

j) * Identity theft where this is accomplished by use of fraudulent computer

transactions.

k) * Writing or spreading computerviruses or worms.



l) * Salami slicing is the practice of stealing money repeatedly in extremely small

quantities.

m) *DNSDenial-of-service attack, where company websites are flooded with service

requests and their website is overloaded and either slowed or crashes completely.

n) * Making and digitally distributing child pornography

Types of Computer Crime Hacking: The activity of breaking into a computer system to gain an unauthorized access is known

as hacking. The act of defeating the security capabilities of a computer system in order to obtain

an illegal access to the information stored on the computer system is called hacking. The

unauthorized revelation of passwords with intent to gain an unauthorized access to the private

communication of an organization of a user is one of the widely known computer crimes. Another highly dangerous computer crime is the hacking of IP addresses in order to transact with a false

identity, thus remaining anonymous while carrying out the criminal activities.

Phishing: Phishing is the act of attempting to acquire sensitive information like usernames,

passwords and credit card details by disguising as a trustworthy source. Phishing is carried out

through emails or by luring the users to enter personal information through fake websites. Criminals

often use websites that have a look and feel of some popular website, which makes the users feel

safe to enter their details there.

Computer Viruses: Computer viruses are computer programs that can replicate themselves and

harm the computer systems on a network without the knowledge of the system users. Viruses

spread to other computers through network file system, through the network, Internet or by the

means of removable devices like USB drives and CDs. Computer viruses are after all, forms of

malicious codes written with an aim to harm a computer system and destroy information. Writing

computer viruses is a criminal activity as virus infections can crash computer systems, thereby

destroying great amounts of critical data.

Cyberstalking: The use of communication technology, mainly the Internet, to torture other

individuals is known as cyberstalking. False accusations, transmission of threats and damage to

data and equipment fall under the class of cyberstalking activities. Cyberstalkers often target the

users by means of chat rooms, online forums and social networking websites to gather user

information and harass the users on the basis of the information gathered. Obscene emails, abusive phone calls and other such serious effects of cyberstalking have made it a type of

computer crime.

Identity Theft: This is one of the most serious frauds as it involves stealing money and obtaining other

benefits through the use of a false identity. It is the act of pretending to be someone else by using

someone else's identity as one's own. Financial identity theft involves the use of a false identity to

obtain goods and services and a commercial identity theft is the using of someone else’s business

name or credit card details for commercial purposes. Identity cloning is the use of another user's

information to pose as a false user. Illegal migration, terrorism and blackmail are often made

possible by means of identity theft.

The different types of computer crimes involve an illegal exploitation of the computer and

communication technology for criminal activities. While the advancing technology has served as a

boon to mankind, the destructively directed human intellects are all set to turn technology into a

curse. However, crimes are sure to end, as it is truth that always triumphs!

1. Intellectual crime – cracking into a computer system with the sole aim of transferring or

stealing funds, e.g. Salami slicing which is the activity of obtaining or stealing money

repeatedly in extremely small quantities over a period of time

2. Destruction of property

3. Software piracy



4. Deliberate circumvention of computer security systems or unauthorized access to or

modification of computer programs and data; i.e. hacking which attempts to bypass the

security mechanism of a computer system or network

5. Theft of computer hardware and software or taking away software without the owner’s

consent

6. Making and distributing pornography

MEASURES TO COUNTER OR COMBAT COMPUTER CRIME [COMPUTER SECURITY] � Careful vetting of employees

� Separation of duties

� Use of passwords � Security manager software-to monitor attempts to access the system whether

successful or not.

� Educating staff

� Prevention of unauthorized access to the computer operations room

� Data Encryption/Decryption

1. Establish strong passwords

Implementing strong passwords is the easiest thing you can do to strengthen your security.

Cloutier shares his tip for crafting a hard-to-crack password: use a combination of capital

and lower-case letters, numbers and symbols and make it 8 to 12 characters long.

You should definitely avoid using: any personal data (such as your birthdate), common words spelled backwards and sequences of characters or numbers, or those that are close

together on the keyboard.

Use their convenient password checker to see how strong yours is.

As for how often you should change your password, Cloutier says that the industry

standard is "every 90 days," but don't hesitate to do it more frequently if your data is highly-

sensitive.

Another key: make sure every individual has their own username and password for any

login system, from desktops to your CMS. "Never just use one shared password," says

Cloutier.

And finally, "Never write it down!" he adds.

2. Put up a strong firewall

In order to have a properly protected network, "firewalls are a must," Cloutier says.

A firewall protects your network by controlling internet traffic coming into and flowing out

of your business. They're pretty standard across the board -- Cloutier recommends any of

the major brands.

3. Install antivirus protection

Antivirus and anti-malware software are essentials in your arsenal of online security weapons, as well.

"They're the last line of defense" should an unwanted attack get through to your network,

Cloutier explains.

4. Update your programs regularly Making sure your computer is "properly patched and updated" is a necessary step towards

being fully protected; there's little point in installing all this great software if you're not going

to maintain it right.

"Your security applications are only as good as their most recent update," Watchinski

explains. "While applications are not 100 percent fool-proof, it is important to regularly

update these tools to help keep your users safe."



Frequently updating your programs keeps you up-to-date on any recent issues or holes

that programmers have fixed.

5. Secure your laptops Because of their portable nature, laptops are at a higher risk of being lost or stolen than

average company desktops. It's important to take some extra steps to make certain your

sensitive data is protected.

Encryption software changes the way information looks on the harddrive so that, without

the correct password, it can't be read.

6. Secure your mobile phones Cloutier points out that smartphones hold so much data these days that you should

consider them almost as valuable as company computers -- and they're much more easily

lost or stolen. As such, securing them is another must. The must-haves for mobile phones:

• Encryption software

• Password-protection (Cloutier also suggests enabling a specific "lock-out" period, wherein after a short amount of time not being used, the phone locks itself)

• Remote wiping enabled 7. Backup regularly

Scheduling regular backups to an external hard drive, or in the cloud, is a painless way to

ensure that all your data is stored safely.

The general rule of thumb for backups: servers should have a complete backup weekly,

and incremental backups every night; personal computers should also be backed up

completely every week, but you can do incremental backups every few days if you like

("however long you could live without your data," Cloutier explains).

Getting your data compromised is a painful experience -- having it all backed up so you

don't completely lose it will make it much less so.

8. Be careful with e-mail, IM and surfing the Web It's not uncommon for a unsuspecting employee to click on a link or download an

attachment that they believe is harmless -- only to discover they've been infected with a

nasty virus, or worse.

9. Educate your employees Teaching your employees about safe online habits and proactive defense is crucial.

"Educating them about what they are doing and why it is dangerous is a more effective

strategy than expecting your IT security staff to constantly react to end users’ bad

decisions," Watchinski says. It's not easy: "One of the most difficult things to do is protect end users against themselves,"

he adds. But ultimately, prevention is the best approach to handling your data security.

Make sure your employees understand how important your company's data is, and all the

measures they can take to protect it.

10. Data encryption Encryption scrambles data, and is used to protect information that is being held on a

computer, stored on external media such as DVDs or transmitted over a network.

11. Intrusion detection These products monitor system and network activity to spot potential security breaches. If

a detection system suspects an attack, it can generate an alarm, such as an email alert,

based upon the type of activity it has identified.

COMPUTER VIRUS

What is it? � An executable computer program written intentionally to alter the way a

computer operates without permission, to do harm to the computer.

Types of Computer Viruses

• Macro Viruses – are programmed as macros and embedded into a file or document and

when the document is opened the virus is activated. A macro is a list of commands or

actions that are found under key names of headings. Macro viruses typically infect global



settings files such as Word templates so that subsequently edited documents are

contaminated with the infective macros

• Boot Sector Viruses – A virus which attaches itself to the first part of the hard disk that is read by the computer upon bootup. These are normally spread by floppy disks. They only

affect the computer’s boot sector such that the next time you try to start the computer it

fails to boot

• Time Bomb – is designed to cause damage to a computer at a specified date and time,

e.g. Friday 13th, March 6th

• Logic Bomb – checks for particular conditions or states of the system which when satisfied

triggers the perpetration of an unauthorized and usually destructive act. It lies dormant for

most of the time and is triggered by an event

• Memory resident virus – resides in a computer’s volatile memory (RAM). • Polymorphic viruses – a virus that not only replicates itself by creating multiple files of itself,

but it also its digital signature every time it replicates. This makes it difficult for less

sophisticated antivirus software to detect

• Program viruses e.g. cascade, pacman 1508, override.

• Boot viruses e.g. pasta, pentagon, Michelangelo

• Internet Viruses e.g. Trojan horse, Stealth DEFINITION2. A virus is acomputer program designed to enter yourcomputer and tamper with your files without

your knowledge. Once the program containing the virus is open, the activated virus can not only

infect other programs and documents on youcomputerr, it can duplicate and transmit itself to

other computers that are connected to yours, just like a physical virus can move from one human

host to another.

Virusesbegan in the late 1980s as personal computers and electronic bulletin boards became

more common. Back then, operating systems, word processing programs and other programs

were stored on floppy disks. Hidden Viruseswere programmed onto these disks; as the disks were

transferred from person to person, the virus spread.

WHO CREATES VIRUSES? Where do Virusescome from? Every virus is created by an author with a different motive—but all virus builders feel their actions are justified. For some, a killer virus is the ultimate technical

challenge, like climbing a mountain. For others, creating Viruses is a form of self-expression. Some

disgruntled employees, consumers or citizens turn to virus building as revenge for perceived

injustices. And though it’s a frightening thought, some Virusesare built and aimed by legitimate (but

disreputable) businesses to weaken competitors. Other virus authors want to make their mark in

Internet history; these writers get a thrill out of seeing their virus cause damage enough to attract

news headlines both online and on the evening news.

What Viruses Do? /Signs & symptoms of an infected computer. � Reduced memory or disk space

� Files are overwritten or damaged

� Hard drive may be erased

� Data is modified /corrupted.

� Change files & date stamp

� Drive lights blink without reason

� Longer times are experienced when loading programs

� Slower system operation.

• Deletion of data files

• The computer completely fails to work

• Erasure or deletion of executable files

• Formatting of the hard disks • Filling up of disk space



• Programs suddenly take longer to load.

• The size of a program changes.

• The disk runs out of free space when it seems to have plenty.

• The CHKDSK command does not show the correct amount of bytes available.

• Bit errors frequently occur while running Windows.

• The disk drive is active when it should not be.

• The hard drive is inaccessible when booting from a floppy drive.

• Unrecognized files appear.

• File names change.

• The keyboard makes a clicking noise.

• The screen becomes distorted.

• Text on screen does unusual things. • CMOS settings, AUTOEXEC.BAT, or CONFIG.SYS files change unexpectedly (Symantec).

A large part of detection is anti-virus software. Like a doctor, anti-virus software often

uses the above listed symptoms to identify and eradicate an infection.

What are the symptoms of an infected computer?

It’s not always easy to tell if your computer has been compromised. More than ever before, the

authors of viruses, worms, Trojans and spyware are going to great lengths to hide their code and

conceal what their programs are doing on an infected computer. That’s why it’s essential to follow

the advice given in this guide: in particular, install Internet security software, make sure you apply

security patches to your operating system and applications and backup your data regularly.

It’s very difficult to provide a list of characteristic symptoms of a compromised computer because the same symptoms can also be caused by hardware and/or software problems. Here are just a

few examples:

• Your computer behaves strangely, i.e. in a way that you haven’t seen before.

• You see unexpected messages or images.

• You hear unexpected sounds, played at random.

• Programs start unexpectedly.

• Your personal firewall tells you that an application has tried to connect to the Internet (and it’s not a program that you ran).

• Your friends tell you that they have received e-mail messages from your address and you

haven’t sent them anything.

• Your computer ‘freezes’ frequently, or programs start running slowly.

• You get lots of system error messages.

• The operating system will not load when you start your computer.

• You notice that files or folders have been deleted or changed.

• You notice hard disk access (shown by one of the small flashing lights) when you’re not aware of any programs running.

• Your web browser behaves erratically, e.g. you can’t close a browser window.

How computers are infected with Viruses?

� Use of infected floppy diskettes on uninfected computers. Floppy disks or other media

that users can exchange.

� Downloading unknown files, when your computer is connected to the Internet.

� Opening an E-mail attachment. Email attachments.

� Accepting unknown program installations from the internet

� Use of network files/direct connection/through networks.

� Software piracy [buying software from unauthorized agents]. Pirated software.

� Booting a PC from an infected medium.

� Executing an infected program.

� Opening an infected file.



� Shareware.

� Viruses may be sent by opening email attachments,

� clicking on spam,

� visiting corrupt websites and links online,

• Opening spreadsheets or even the original method—infected disks.

• But the Internet is now the superhighway for virus transmission. Sharing of storage media

• Through e-mail attachments

• Networks – if your computer is connected to a home network or if your work computer is

part of network, you may find yourself with an infection through no fault of your own. There

isn’t much you can do to stop these kinds of infections, short of having your network

administrator ensure that everyone’s antivirus software is up to date so that the invading bug can be removed as quickly as possible.

• Internet downloads including software piracy

• Rogue Websites. It is depressing to know that you may become infected with spyware or a

virus by doing nothing more than simply visiting a website, but it is true. Many adult

websites, gambling websites and other less than trustworthy websites will attempt to

automatically access your computer when you visit them. They often install adware bugs

that will cause a flurry of pop ups to appear on your screen. This adware will often allow for

other programs with even more nefarious purposes to be installed and before you know it,

your computer will be swamped. To stop these rogue websites, adjust the settings on your

antivirus software and firewall so that no outside connections can be made and no

programs can be installed without your express permission.

CHARACTERISTICS and ATTRIBUTES OF COMPUTER VIRUSES

The demonstrated characteristics of computer viruses include several remarkable items, including

size, versatility, propagation, effectiveness, functionality, and persistence.

1) Size.The sizes of the program code required for computer viruses has been demonstrated to be

surprisingly small. This has facilitated the ability of these programs to attach themselves to other

applications and escape notice for long periods of time.

2) Versatility.computer viruses have appeared with the ability to generically attack a wide variety

of applications. Many do not even require information about the program they are infecting.

3) Propagation. Once a computer virus has infected a program, while this program is running, the

virus is able to spread to other programs and files accessible to the computer system. The

ability to propagate is essential to a virus program.

4) Effectiveness. Many of thecomputer viruses that have received widespread publicity have had

far-reaching and catastrophic effects on their victims. These have included total loss of data,

programs, and even the operating systems.

5) Functionality. A wide variety of functions has been demonstrated in virus programs. Some virus

programs merely spread themselves to applications without otherwise attacking data files,

program functions, or operating systems activities. Other virus programs are programmed to

damage or delete files and systems. The effectiveness of these programs is enhanced through

the use of several phases of operation, in which the virus propagates through a system or lies

dormant until triggered by a specified event. This allows the virus program increased time to

spread before the victim system's user becomes aware of its presence.

6) Persistence. Even after the virus program has been detected, recovery of data, programs, and

even system operation has been difficult and time consuming. In many cases, especially in

networked operations, eradication of viruses has been complicated by the ability of the virus

program to repeatedly spread and reoccur through the networked system from a single infected copy.



Attributes of computer viruses o Auto replicating [self replicating].

o Attaches itself to a program or file

o It infects as it travels

o Reproduces itself

o Distribute itself

o Copies itself

o Duplicate copies of itself

o It spreads o It is software o It can destroy o It hides

DESTRUCTIVE EFFECTS OF COMPUTER VIRUSES o Cause damage to data

o Extract data from machines for spying or theft

o Slow machine performance

o Corrupt data

o Damage software, hardware and files

o Damage the computer by damaging programs

o Reformatting of the hard disk

o Deletion of files

ANTIVIRUS TOOLS/PACKAGES/SOFTWARE

1) Dr Solomon’s Antiviral

Package

2) Norton Antivirus Package

3) AVG Antivirus

4) Microsoft Antiviral Package

5) McAfee VirusScan

6) F-PROT anti-virus package 7) Protector Plus 2000 for

Windows ver 7.2.H03

8) Anti Trojan Elite ver 3.7.5 9) Panda Antivirus platinum 7

ver 7.06

10) AntiSpy ver 4.4.2 11) avast! 4 Professional Edition

ver 4.6.652

12) DrWebÂ® Anti-Virus, Home Edition ver 4.30a

13) Dr.Web Anti-Virus for Workstations ver 4.30.a

14) File Sharing Sentinel ver 1.0.1 15) Real Password Protector

2005 ver 2.0

16) Code(Red) Hunter v1.5 ver v1.5

17) Digital Patrol ver 5.00.12 18) BitDefender 19) Kaspersky 20) F-Secure Anti-Virus 21) PC-cillin 22) ESET Nod32 23) CA Antivirus 24) Norman Virus Control

25) AntiVirusKit 26) AVAST! 27) Panda Titanium

28) Windows OneCare

29) ViRobot Expert 30) PCTools AntiVirus 31) WinAntiVirus

32) CyberScrub AntiVirus 33) The Shield AntiVirus



SCANNER – examine every file on a specific disk drive, looking/searching for known virus

“signatures”. A “signature” is a string of software code that identifies a virus program. Every virus

has a unique signature

MEASURES/FACILITIES PROVIDED BY AN ANTIVIRUS PACKAGE.

1. Scanning – searching for viruses 2. Cleaning of the system (removal of viruses)

3. Rearrangement of corrupted data. 4. Repairing of corrupted data files. 5. Quarantine – separation of infected files from uninfected files.

6. Prevention includes creating user awareness, implementing hygiene rules, using disk authorization software, or providing isolated 'quarantine' PCs.

7. Detection involves the use of anti-virus software to detect, report and (sometimes)

disinfect viruses..

8. Containment involves identifying and isolating the infected items.

9. Recovery involves disinfecting or removing infected items, and recovering or replacing

corrupted data.

PRECAUTIONS/SAFETY GUIDES AGAINST VIRUSES

� Install a reliable antiviral package

� Avoid Software piracy thus buy software from authorized dealers.

� Never download unknown files from the internet

� Boot the system from virus free disks � Using write protect tabs on floppy disks

� Scan every floppy diskette for viruses before use. Unknown floppy diskettes should

not be used

� Avoid using foreign storage media

� Use genuine software

� Avoid opening e-mails from suspicious or unknown sources

� Write protect disks

� Install antivirus software, e.g. Avira, Eset Nod32, AVG, Norton, Dr. Solomon’s Toolkit

• Install a reliable anti virus program – From the first moment you turn your computer on, you should

have a trusted anti virus program by your side. Even if you have a machine that isn’t hooked up to

the Internet, a reliable anti virus program is a low cost and common sense addition to any

machine. There are even free anti virus programs you can download that work almost as well as

industry giants like Norton and McAfee.

• Install anti-spyware and anti-malware programs – As good as the best anti virus programs are, they

sometimes need a little bit of help. Thankfully, many of the top anti-spyware programs are

completely free. Spybot Search and Destroy and CCleaner are just two free programs that can

help prevent computer viruses from doing any damage on your machine. As helpful as these

programs are, however, you must update them and run them on a regular basis for them to do

any good.

• Avoid suspicious websites – A good virus protection program will alert you when you visit a website

that attempts to install or run a program on your computer. Many less than reputable adult websites do this, so if you get a warning, don’t go back, you may end up with a bug you can’t get

rid of.

• Never Open Email Attachments Without Scanning Them First – The most common way viruses are

spread throughout the Internet is still via email. Some attachments, like pictures, now display in

emails and don’t require an attachment to be manually opened, but other documents do. Make

sure you use an email client that scans all email attachments before you are allowed to open

them. This will help prevent computer viruses from getting a foothold on your machine.

• Set up Automatic Scans – Many of the top anti virus programs, as well as the best anti-spyware

programs, now have settings that will let them automatically run during down times or in the

middle of the night. Of course, your computer must be on for this to happen, but having daily

scans run when nothing else is going on is a great way to prevent even the latest computer viruses


46 rrmmmmaakkaahhaa@@ggmmaaiill..ccoomm

from sticking around too long.

• Watch Your Downloads – Part of the fun of the Internet is downloading music, movies and other

items. However, since these downloads are so massive, it can be easy to sneak a virus along for

the ride. Only download these files from trusted sites that you can count on, or, at the very least,

scan them before you open them.

• Updates, Updates, Updates – There is a reason why Windows has a feature called Critical Updates.

There is an entire branch of Microsoft dedicated to staying one step ahead of the hackers out

there so when they manage to fix a possible security loophole, you need to download the patch

right away. Help Microsoft help you prevent computer viruses from causing too much trouble. • Know What To Look For – Even if you are just a casual computer user, you should have an idea of

how your machine operates, what normal pop up windows look like and what popular viruses are

out there, that way, when your computer begins exhibiting tell tale signs, you’ll know. You can help

prevent computer viruses by staying updated and educated.

• Stay Away From Cracked Software – It is so secret that you can download illegal, cracked versions of some programs online. As tempting as it may be, these files are almost always infested with

advanced and difficult to detect bugs. Play it safe and get your software from the source.

• Install a Firewall – A firewall is a program that screens incoming Internet and network traffic. Along

with your virus program, it can help prevent unauthorized access to your computer.

• Be prepared to Lock Down – If you hear of a virus that is spreading like wildfire through the Internet, make an extra effort to be careful. Don’t open any suspicious emails or accept any downloads for

a week or two until your virus protection program has been updated and you are, once again,

safe.

COMPUTER LANGUAGES

(a) Machine Language � A computer language made up of binary digits (0s and 1s)

� The most fundamental way to program a computer, using instructions made up entirely of

strings of 0sand 1s.

� The language is far from English and any mathematical notation.

� Machine language is not portable and is machine dependent meaning it cannot be moved

from one machine to the other.

� Errors are very difficult to remove and programs are difficult to write using machine language.

(b) Low Level Language � Low level means the language can better communicate with the system.

� LLL are closer to machine code

� They use mnemonics i.e. ADD to add SUB to subtract etc

� Easier for a programmer to write a program in LLL than machine language.

� Programs have to be translated from source code into machine language

(c) High Level Language � A programming language that utilizes macroinstructions and statements that closely resembles

human language or mathematical notation to describe the problem to be solved or the procedure to be used.

� Programs are much easier to write / read because the are next English

� [English like statements].

� A programming language where each instruction corresponds to several machine code

instructions. A compiler or interpreter must translate instructions in this language before they

can be processed.

MACHINE LANGUAGE ADVANTAGES DISADVANTAGES

• A very powerful language

• No translation is needed

• Much harder to code for programmers

because it’s a series of 1s & 0s.

• Not portable • Machine Dependent

• Errors are difficult to remove

LOW LEVEL LANGUAGE



ADVANTAGES DISADVANTAGES

• Easier to use than machine language • Machine dependent

• Harder to code than HLL

• Not portable

HIGH LEVEL LANGUAGE ADVANTAGES DISADVANTAGES

• It is a portable language

• Programs are much easier to read/

write coz it’s close to English language.

• Programs are problem oriented.

• Errors are removed before translation to

Machine code [during compiling].

• Slower in execution

• Programs tend to be wordy hence they

take long to compile.

• Requires more memory.

� LANGUAGE TRANSLATOR PROGRAMS

� A Translator is a program that translates a source program/code into an equivalent object

code [machine code] before the program is executed by the computer.

� Compiler � Translates a complete program written in HLL into machine code before it is

executed.

� Produces a translated document.

� E.g. COBOL compiler.

� Assembler � Translates a source program written in assembly language into machine code.

� Interpreter � A computer program that translates one statement at a time [source code] and

generates the machine code for that statement only & executes it there & there before

moving to the next line/statement.

� Interpreter translates line per line and does not produce a translated document.

� E.g. Pascal Interpreter, BASIC Interpreter.

Compare & contrast Interpreter & Compiler 1) Compiler- fast execution of program.

2) Interpreter- Slowed down execution of program.

3) Compiler- compiler time overhead.

4) Interpreter- No compiler time overhead

5) Compiler- Stand alone executables

6) Interpreter- Dependency on interpreter

7) Compiler- Compiler is complex [time, space]

8) Interpreter- Relative simplicity of interpreter

List the advantages & disadvantages of interpreters & compilers. 1. A compiled program will always run faster than an interpreted one

2. Object code generated by compilers may be saved on disk & run as many times as required

without being compiled.

3. A compiler gives more helpful error messages.

4. Compiler gives the line number where the error has occurred.

5. An interpreter will find the error at the first instance whereas the compiler will list all errors after

compiling.

6. A compiler will check the syntax of the entire program whereas the interpreter only checks the

syntax of statements that are executed during that particular run of a program.

7. Interpreters are very convenient for program development, since making modifications does

not mean the whole program has to be reloaded & recompiled which takes considerable

time.

8. Interpreter is cheaper than compiler & is simpler to use



Translation process

9. Many interpreters will allow a program to run up to a point where an error occurs, let the

programmer fix the error & then continue to run the program from that point.

10. With an interpreter debugging is easier since the code is executed line by line.

11. Line by line interpretation can be slow 12. Interpreter can test your code as you write it 13. With an Interpreter there is no need to create object code & link programs.

Language Processors and Translator Programs • These are programs that are used to convert high and low level language programs into

machine code, i.e. into a form directly understood by the computer. There are three main

types of translator programs:

• Human programmers write programs in a language that is easy to understand for them

• They use language translators to convert that program into machine language – a

language that is easy to understand for the processor

a) Assemblers They translate programs written in assembly language into machine code

b) Interpreters Convert HLL programs into machine by translating one program statement at a

time before it can be executed. No object code is stored, e.g. QBASIC

Interpreter translates the HLL program one statement at time. It reads a single

statement, translates it into machine language and passes that machine

language code to the processor and then translates the next statement, and so

on …

c) Compilers Like interpreters they also translate HLL programs into machine code. They

however differ from interpreters in that a whole program is translated at a time.

The object code which is created can either be executed immediately or saved

for later execution.

Compiler translates the program written in a HLL in one go. The translated code is

then used by the processor whenever the program needs to be run

Development Software/Programming Languages It allows the user to create software for various applications. All software programmes (systems and

application) are written in coding schemes called programming languages. The primary function of a programming language is to provide instructions to the computer system so that it can

perform a processing activity to achieve an objective or solve a problem. Programme code is the

set of instructions that signal the CPU to perform circuit-switching operations. Programming

languages have four categories:

• Low-level languages

• High-level languages

• Fourth generation languages

• Fifth generation languages

Source code

(Human

readable)

Object code

(Machine

readable)



Low Level Languages

• Low level computer languages are machine codes or close to it.

• Computer cannot understand instructions given in high level languages or in English. It can

only understand and execute instructions given in the form of machine language i.e.

language of 0 and 1.

• There are two types of low level languages. The lowest-level language is Machine

Language, which hides no details of the machine; not even the bit patterns used to form

instructions are abstracted.

• Low-level languages have the advantage that the programmer is able to tune the code

to be smaller or more efficient, and that more system-dependent features are sometimes

available. They have the disadvantage that they are often (usually?) harder to program

with than HLLs.

First generation languages (abbreviated as 1GL) • The most elementary and first type of computer, which was invented, was machine

language. Machine language was machine dependent.

• A program written in machine language cannot be run on another type of computer

without significant alterations. Machine language is sometimes also referred as the binary

language i-e, the language of 0 and 1 where 0 stands for the absence of electric pulse

and stands for the presence of electric pulse. Very few computer programs are actually

written in machine language.

• It is the lowest and most elementary level of programming language and was the first type

of programming language to be developed. Machine language is basically the only

language which computer can understand.

• In fact, a manufacturer designs a computer to obey just one language, its machine code,

which is represented inside the computer by a string of binary digits (bits) 0 and 1. The

symbol 0 stands for the absence of electrical pulse and 1 for the presence of an electrical

pulse. Since a computer is capable of recognizing electric signals, therefore, it understands

machine language.

• Represent the very early, primitive computer languages that consisted entirely of 1's and

0's - the actual language that the computer understands (machine language).

• The main benefit of programming in machine code is that the code a user writes can run

very fast and efficiently, since it is directly executed by the CPU. However, machine code

is a lot more difficult to learn than higher generational programming languages, and it is

far more difficult to edit if errors occur.

Advantages of Machine Language

i) It makes fast and efficient use of the computer.

ii) It requires no translator to translate the code i.e. directly understood by the

computer

Disadvantages of Machine Language:



i) All operation codes have to be remembered

ii) All memory addresses have to be remembered.

iii) It is hard to amend or find errors in a program written in the machine

language

iv) These languages are machine dependent i.e. a particular machine

language can be used on only one type of computer

Second generation languages (2GL) – Assembly Language

• As computer became more popular, it became quite apparent that machine language

programming was simply too slow tedious for most programmers. Assembly languages are

also called as low level language instead of using the string of members programmers

began using English like abbreviation to represent the elementary operation.

• The language provided an opportunity to the programmers to use English like words that

were called MNEMONICS.

• It was developed to overcome some of the many inconveniences of machine language.

This is another low level but a very important language in which operation codes and

operands are given in the form of alphanumeric symbols instead of 0’s and l’s.

• These alphanumeric symbols will be known as mnemonic codes and can have maximum

up to 5 letter combination e.g. ADD for addition, SUB for subtraction, START,LABEL etc.

Because of this feature it is also known as ‘Symbolic Programming Language’. This

language is also very difficult and needs a lot of practice to master it because very small

• English support is given to this language. The language mainly helps in compiler

orientations. The instructions of the Assembly language will also be converted to machine

codes by language translator to be executed by the computer.

• It represents a step up from the first generation languages. Allow for the use of symbolic

names instead of just numbers. Second generation languages are known as assembly

languages. Code written in an assembly language is converted into machine language

(1GL).

• Assembly language consists of letters of the alphabet. This makes programming much

easier than trying to program a series of zeros and ones. As an added programming assist,

assembly language makes use of mnemonics, or memory aids, which are easier for the

human programmer to recall than are numerical codes.

Advantages of Assembly Language

i) It is easier to understand and use as compared to machine language.

ii) It is easy to locate and correct errors.

iii) It is modified easily



Disadvantages of Assembly Language

i) Like machine language it is also machine dependent.

ii) Since it is machine dependent therefore programmer Should have the knowledge

of the hardware also.

High Level Languages

• The assembly languages started using English like words but still it was difficult to learn

these languages. High level languages are the computer language in which it is much

easier to write a program than the low level language.

• High level computer languages give formats close to English language and the purpose of

developing high level languages is to enable people to write programs easily and in their

own native language environment (English). High-level languages are basically symbolic

languages that use English words and/or mathematical symbols rather than mnemonic

codes. Each instruction in the high level language is translated into many machine

language instructions thus showing one-to-many translation

Advantages of High Level Language

• User-friendly

• Similar to English with vocabulary of words and symbols

• They require less time to write.

• They are easier to maintain.

• Problem oriented rather than 'machine' based.

• Program written in a high-level language can be translated into many machine

language and therefore can run on any computer for which there exists an appropriate translator.

• It is independent of the machine on which it is used i.e. Programs developed in

high level language can be run on any Computer

• Easier to learn and understand than an assembler language as instructions (statements) that resemble human language or the standard notation of

mathematics.

• Have less-rigid rules, forms, and syntaxes, so the potential for error is reduced.

• Are machine-independent programs therefore programs written in a high-level

language do not have to be reprogrammed when a new computer is installed.

• Programmers do not have to learn a new language for each computer they

program.

• Instructions are much easier to remember and use that assembly language instructions

• Fewer instructions are required to write a program than when using assembly language.

• A program can usually be developed much more quickly using a high level

language than an assembly language.

• A program written in a high level language on one type of computer can usually

be converted to operate on another type of computer quite easily. Because of

this high level language programs are described as being portable.

•

Disadvantages of High Level Language

• A high-level language has to be translated into the machine language by a translator and thus a price in computer time is paid.



• The object code generated by a translator might be inefficient Compared to an

equivalent assembly language program

• Types of computer languages - as we human beings communicate with each others in different language such as Urdu, French, Punjabi and Arabic etc. Similarly

to communicate with the computers we have to use specific languages and for

this purpose hundreds of languages have been developed

• Less efficient than assembler language programs and require a greater amount of computer time for translation into machine instructions.

• High level language programs normally take up more space and execute more slowly than equivalent assembly language programs

Types of High Level Languages

Many languages have been developed for achieving different variety of tasks, some are fairly

specialized others are quite general purpose.

These are categorized according to their use as

a) Algebraic Formula-Type Processing. These languages are oriented towards the computational

procedures for solving mathematical and statistical problem

Examples are

• BASIC (Beginners All Purpose Symbolic Instruction Code).

• FORTRAN (Formula Translation).

• PL/I (Programming Language, Version 1).

• ALGOL (Algorithmic Language).

• APL (A Programming Language).

b) Business Data Processing:

• These languages emphasize their capabilities for maintaining data processing procedures

and files handling problems. Examples are:

• COBOL (Common Business Oriented Language).

• RPG (Report Program Generator

b) String and List Processing: These are used for string manipulation including search for patterns,

inserting and deleting characters. Examples are:

• LISP (List Processing).

• Prolog (Program in Logic).

Object Oriented Programming Language

In OOP, the computer program is divided into objects. Examples are:

• C++

• Java

e) Visual programming language: these are designed for building Windows-based applications

Examples are:

• Visual Basic

• Visual Java



• Visual C

Third generation languages (3GL)

With the languages introduced by the third generation of computer programming, words and

commands (instead of just symbols and numbers) were being used. These languages therefore,

had syntax that was much easier to understand.

• Third generation languages are known as "high level languages" and include C, C++, Java,

and JavaScript, among others.

Fourth generation languages (4GL)

♣ The syntax used in 4GL is very close to human language, an improvement from the

pervious generation of languages. 4GL languages are typically used to access databases

and include SQL and ColdFusion, among others.

VERY HIGH LEVEL LANGUAGES (VHLL)

Fifth generation languages (5GL)

Fifth generation languages are currently being used for neural networks. A nueral network is a form

of artificial intelligence that attempts to imitate how the human mind works.

• 5GL is an abbreviation for fifth-generation language. Fifth-generation programming

languages emerged along with the research in Artificial Intelligence (AI). Most constraint-

based and logic programming languages and some declarative languages are fifth-

generation languages. Fifth-generation languages are designed to make

the computer solve the problem for you as oppose to using an algorithm written by a

programmer.

• The idea of fifth generation languages was popular in 1990s. Japan put much research

and money into their fifth-generation computer systems project. Prolog, Mercury, and

OPS5 are the best known fifth-generation languages.

• These are used to create programs for artificial intelligence and expert system and are

sometimes called natural languages because they use English syntax. Allow programmers

to communicate with the computer using normal sentences.

GENERIC SOFTWARE AND THE ORGANISATION OF DATA Define Software Are basically programs, which are in a computer system?



Computer programs and procedures concerned with the operation of a computer system.

Definitions of software on the Web:

• Written coded commands that tell a computer what tasks to perform. For example, Word,

PhotoShop, Picture Easy, and Photo Deluxe are software programs.

• Coded instructions (programs) that make a computer do useful work.

Computer software refers to the various programs or instructions that are stored in the computer

(stored program concept) and used to either manage or control the operation of a computer

system or to direct the computer in solving specific problems. Software is divided into two major

types. SOFTWARE HIERARCHY

TYPES OF SOFTWARE



SYSTEM SOFTWARE

• Refers to the operating system and all utilityprograms that manage computerresources at

a low level. Programs that control and support operations of a computer system.

• Systems software includes compilers, loaders, linkers, and debuggers.

• System software includes a variety of programs such Operating Systems, DBMS,

Communication control programs. Service and utility programs, and programming

language translators.

• Definitions of system software A term for a complicated set of programs that act together to allow a computer, and

other programs, to function. Different from an page layout application that the user may

have, system software is what allows the page layout application to interact with the

monitor display, the RAM, the hard drive and the rest of the computer.

OPERATING SYSTEM

• The main control of a computer system. • It is a system of programs that controls & coordinates the execution of computer programs

and may provide scheduling, debugging, input/output control, system accounting,

compilation, storage assignment, data management and related services.

Definitions of operating system on the Web:

• The software that the rest of the software depends on to make the computer functional. On most PCs this is Windows or the Macintosh OS. Unix and Linux are other operating

systems often found in scientific and technical environments.

• A computer program that controls the components of a computer system and facilitates the operation of applications. Windows Me, Windows XP, Linux, and MacOS are common

operating systems.

APPLICATION SOFTWARE o Applications software comprises programs designed for an end user, such as word

processors, database systems, and spreadsheet programs.

o Programs that specify the information processing activities required for the completion of

specific tasks of computer users. E.g. Electronic Spreadsheet and word processing

programs or inventory or payroll programs.



o Software that is designed and written for a specific personal,

organizational, or processing task, such as graphics software.

o These programs accomplish the specialized tasks of the user, while

operating system software allows the computer to work. A computer-

aided dispatch system is application software, as is each word processing

program.

FREEWARE � Public domain softwarethat is freely available in magazines and on the internet at

no charge to users though manuals may be offered at a cost. Freeware may or

may not have copyrights and may or may not have distribution restrictions.

SHAREWARE � Refers to software that is widely distributed in much the same way as freeware BUT

is always copyrighted and includes a software license that requires its users to pay

for the privilege of using the software beyond a certain trial period. If you decide

to use it, you are expected to pay for the license. There is usually a disabling

system in the program after a certain period of time i.e. a month.

OPERATING SYSTEM

� Are programs that create an environment, which enables us to use computers?

� Is an integrated system of program that manages the operations of the CPU, controls the

input/output and storage resources and activities of the computer system, and provides

various support services as the computer executes the application programs?

� Is a set of software routines that communicate between application programs and the

hardware?

� All communications go through the operating system.

� E.g. when a user issues a command to print, the O/S receives the command &

processes it according to priorities with the use of interrupts.

� Once the processor is free to execute the command, the O/S sends the message

to the processor & receives the output, which is then directed to the printer.

MAJOR OPERATING SYSTEMS

MS-DOS (Microsoft Disk Operating System) • It has been widely used especially before 1995 when the new Windows 95 took over.

• It is a single user operating system – only one user can be using the system at a given time.

• It is a single tasking operating system – It allows for the processing of only one task at a time

• Use of short prompt commands – the user interfaces with the computer system through the

use of commands that are fed into the computer usually after the prompt sign (>) e.g.

C:\>cls (Command to clear the screen)

• Instructions are put in only through the keyboard

• Once a file is deleted it can never be recalled

• The operating system is not user-friendly

Windows • A windows based operating system is more advanced than the MS-DOS based operating

system.

• It features graphical user interfaces (GUIs) – User can feed commands into the computer

through the selection of relevant icons, bars, buttons, boxes or other forms of images

(mostly resembling the intended device or operation).

• True multitasking – the operating system allows for numerous tasks to be done at the same

time.

• Networking – the operating system is multi-usable – many users can use it at the same time.

It is capable of holding a number of computer systems networked together.



• Multimedia Presentations- the operating system allows for the presentation of information

in a variety of media including text, graphic displays, voice and other audio, photographs

and video.

• Virtual Memory – It allows for the use of storage devices as extension of the main memory

thus giving the appearance of a larger main memory than actually exists.

• Deleted files go to the recycle bin

• Makes use of easier input methods, e.g. mouse, joystick

• Windows operating system has MS-DOS option

• Examples of Windows Operating Systems packages, Windows NT (new technology) and

Windows 95.

• In computer terms, a window is one section of a computer’s multiple section display

screen that can have a different display.

OS/2 • It is called the Operating System /2

• It is an operating system developed by IBM and was introduced in 1994 with the OS/2

Warp version as the latest one.

• It provides graphical user interfaces (GUIs), multitasking, virtual memory and

telecommunications.

UNIX

• Originally developed by AT&T but now being offered by many other vendors.

• It is a multitasking, multi-user and net-work managing operating system

• Because of its portability, it can be used on mainframes, midrange computers and

microcomputers.

• It is a popular choice for network servers.

The Macintosh System/Mac OS • It is an operating system for Apple from Macintosh microcomputers

• It is a popular GUI as well as multitasking and virtual memory operating system.

Types /EXAMPLES of operating systems

There are several types of operating system, defined according to whether they can

simultaneously manage information measuring 16 bits, 32 bits, 64 bits or more.

OPERATING SYSTEM PROGRAMMING SINGLE USER MULTI USER SINGLE TASK MULTI TASK

1. MS DOS 16 bits X X

2. Windows3.1 16/32 bits X not pre-emptive

3.Windows95/98/Me 32 bits X cooperative

4.WindowsNT/2000 32 bits X pre-emptive

5.WindowsXP 32/64 bits X pre-emptive

6.Unix / Linux 32/64 bits X pre-emptive

7.MAC/OS X 32 bits X pre-emptive

8.VMS 32 bits X pre-emptive

9.Windows Vista

10.Windows 7



BOOTING(also known as "booting up") is a bootstrapping process that starts operating systems

when the user turns on a computer system. A boot sequence is the initial set of operations that the computer performs when power is switched on. The bootloader typically loads the main operating

system for the computer.

Rebooting Hard reboot

� A hard reboot (also known as a cold reboot, cold boot or cold start) is when power to

a computer is cycled (turned off and then on) or a special reset signal to the

processor is triggered. This restarts the computer without first performing any shut-

down procedure. (With many operating systems, especially those using disk caches,

after a hard reboot the filesystem may be in an "unclean" state, and an automatic

scan of on-disk filesystem structures will be done before normal operation can begin.)

It may be caused by power failure, be done by accident, or be done deliberately as

a last resort to forcibly retrieve the system from instances such as a critical error or

virus-inflicted DoS attack. It can also be used by intruders to access cryptographic

keys from RAM, in which case it is called a cold boot attack.

Soft reboot � A soft reboot (also known as a warm reboot) is restarting a computer under software

control, without removing power or (directly) triggering a reset line. It usually, though not always, refers to an orderly shutdown and restarting of the machine.

� The Control-Alt-Delete key combination on the original IBM PC was designed to allow

a soft reboot for a quicker and more convenient (and, some argue[who?], less stressful

on system components) restart than powering the computer completely down then

back up.

� This kind of reboot will not usually reset the hard disks, so that they have time to

update their write cache to permanent storage. Hard disks will also keep their

configuration (like C/H/S adjustments, HPA, DCO, internal passwords...) over these

reboots.

� The Linux kernel has optional support for the kexecsystem call, which transfers

execution to a new kernel and skips hardware or firmware reboot. The entire process

is done independent of the system firmware. Note that the kernel being executed

does not have to be a Linux kernel.

� Sometimes, the computer does not respond and in that case it can be restarted by

pressing Ctrl+Alt+Del keys. The process of starting the computer using these keys is

called warm booting or softbooting. Random reboot

� Random reboot is a non-technical term referring to an unintended (and often undesired)

reboot for which the cause is not immediately evident to the user. Such reboots may occur

due to a multitude of software and hardware problems, such as triple faults.

� As Windows XP/Vista has an option to skip its Blue Screen of Death (Blue Screens of Death

in Windows XP/Vista offer no option of pressing any key and seeing if the computer

continues functioning) and immediately restarts the computer in the event of a fatal error, users can be mistaken in thinking a Windows XP/Vista computer suffers from random

rebooting.

� Also, If a Wii game has a disc failure or the Wii game disk is dirty, it will reboot to the Wrist

Strap screen.

Errors � In Windows, when an error occurs in the boot process, a Blue Screen of Death or a Black

Screen of Death may occur. On UNIX and Unix-like operating systems, such as Linux, a fatal

error in the boot process may cause a kernel panic.

FACTORS ONE SHOULD CONSIDER WHEN

• Making comparisons of the microcomputer operating systems available in the organization

• Making microcomputer operating system acquisition decision.



� Is the OS a single or multitasking operating system? Many microcomputer OS are

single tasking, meaning they allow only one person to run one program at a time.

Multitasking and multi-user OS permit more than one program to run and more than

one person to use the system at one time. Multitasking OS may allow a user to receive

a fax message at the same time one is searching a database.

� Is it a task switching operating system? A task switching OS lets one load more than

one program at a time and allows switching between the programs. The task that one

is working with is the foreground task and the suspended tasks are background tasks.

� What utilities are available with the OS? Some of the most commonly used utilities on

microcomputer OS are delete, copy contents of one diskette to another, format a

diskette, delete files stored in a diskette, and compress data.

� Is the OS hardware dependent? An OS may be limited to running on specific hardware

or may have versions that allow it to run on different types of computer systems.

� What user interface is offered by the operating system? Graphical User Interface and Command Driven User Interface are examples of user interfaces. See Interface

section.

Types of operating systems � Multiprocessing

� Multitasking � Multi-user

� Multi programming

� Single user

Modes of operation/ Operating system techniques Computers can operate in many different ways requiring different and complex operating systems.

Real time processing � When the computer has to react within a guaranteed time to an input, a real time

operating system is used. For example, the engine management system within a car

uses a real time operating system in order to react to all the things going on within the

engine. A real time operating system does not necessarily have to be fast. It simply has

to be quick enough to respond to inputs in a predictable way. Embedded computers

often contain an RTOS as many are used to control something.

� Computers operating in real time are often dedicated to the control of systems such as industrial processes, planes and space flights. Another example of real time

processing is computer games. For example, when an action is selected in a game,

the data is fed back to the computer and the systems updated.

Multi-programming � Multi-programming is a method of operating such that several programs appear to be

running at once.

� The jobs are usually given priorities. The operating system switches jobs in and out of

processor time according to priority. For example, while one job is being allocated printer time, another will be being processed in memory. The processor is so fast that it seems that many jobs are being processed at the same time.

Multi-tasking � This isn't just about running more than one application at the same time. Multi-tasking

allows multiple tasks to run concurrently, taking turns using the resources of the computer.

� This can mean running a couple of applications, sending a document to the printer

and downloading a web page.

� However, operating systems are not truly multi-tasking - in order to do this, you would

need parallel processors, which are now appearing on personal computers.

Multiprocessing � An operating system technique which can manage multiple instruction processors,

assigning each to operate upon a different instruction stream (program or job)

concurrently.



� Multiprocessing is the use of two or more central processing units (CPUs) within a single

computer system. The term also refers to the ability of a system to support more than one

processor and/or the ability to allocate tasks between them.[1] There are many variations

on this basic theme, and the definition of multiprocessing can vary with context, mostly as

a function of how CPUs are defined (multiple cores on one die, multiple chips in one

package, multiple packages in one system unit, etc.).

� Multiprocessing sometimes refers to the execution of multiple concurrent software

processes in a system as opposed to a single process at any one instant. However, the

terms multitasking or multiprogramming are more appropriate to describe this concept,

which is implemented mostly in software, whereas multiprocessing is more appropriate to

describe the use of multiple hardware CPUs. A system can be both multiprocessing and

multiprogramming, only one of the two, or neither of the two.

Multi-access or multi-user � A multi-access (or multi-user) system is one where a number of users are able to use the

same system together.

� Modern personal computers can allow multi user access i.e. more than one person can

make use of the computer resources at the same time via a LAN.

� The central processor deals with users in turn; clearly the more users, the slower the

response time. Generally, however, the processor is so fast that the response time at the

most is a fraction of a second and the user feels they are being dealt with immediately. o Multi-user is a term that defines an operating system or application software that

allows concurrent access by multiple users of a computer. Time-sharing systems

are multi-user systems. Most batch processing systems for mainframe computers

may also be considered "multi-user", to avoid leaving the CPU idle while it waits for

I/O operations to complete. However, the term "multitasking" is more common in

this context.

o An example is a UNIX server where multiple remote users have access (such as via

Secure Shell) to the UNIX shell prompt at the same time. Another example uses

multiple X Window sessions spread across multiple terminals powered by a single

machine - this is an example of the use of thin client.

o Management systems are implicitly designed to be used by multiple users,

typically one system administrator or more and an end-user community.

Single-user � Is most commonly used when talking about an operating system being usable only by one

person at a time, or in reference to a single-user software license agreement. Multi-user

operating systems such as UNIX sometimes have a single user process available for

emergency maintenance.

Batch processing � A batch processing system is where programs or data are collected together in a batch

and processed in one go. Typically the processing of payrolls, electricity bills, invoices and

daily transactions are dealt with this way.

� This method of operation lends itself to jobs with similar inputs, processing and outputs

where no human intervention is needed. Jobs are stored in a queue until the computer is ready to deal with them. Often batch processed jobs are done overnight.

ROLES (functions) OF THE OPERATING SYSTEM

The operating system has various roles:

1. Management of the processor: the operating system is responsible for managing allocation of the processor between the different programmes using a scheduling algorithm. The type of scheduler is totally dependent on the operating system,

according to the desired objective.

The OS is responsible for managing the allocation of processor time to the different

programs that will be using the computer. The processor can only execute one

instruction at a time and in a multi-user system, conflicts are bound to arise when

several user programs request usage of the processor at the same time. The OS



therefore allocates processor time to all users either in a round robin fashion or using a

system of priorities.

2. Management of the random access memory: the operating system is responsible for

managing the memory space allocated to each application and, where relevant, to

each user. If there is insufficient physical memory, the operating system can create a memory zone on the hard drive, known as "virtual memory". The virtual memory lets

you run applications requiring more memory than there is available RAM on the

system. However, this memory is a great deal slower.

The OS is responsible for managing the memory space allocated to each application.

If there is insufficient physical memory the OS can create a memory zone on the hard

drive known as virtual memory which lets you run applications requiring more memory

than is available on the system.

The operating system is responsible for the following activities in connections with

memory management.

Keep track of which parts of memory are currently being used and by whom.

Decide which processes to load when memory space becomes available.

Allocate and deallocate memory space as needed

3.

4. Management of input/output: the operating system allows unification and control of

access of programmes to material resources via drivers (also known as peripheral

administrators or input/output administrators).

5. Management of execution of applications: the operating system is responsible for smooth execution of applications by allocating the resources required for them to

operate. This means an application that is not responding correctly can be "killed".

6. Management of authorisations: the operating system is responsible for security relating to execution of programmes by guaranteeing that the resources are used only by

programmes and users with the relevent authorisations.

7. File management: the operating system manages reading and writing in the file system and the user and application file access authorisations.

The OS manages reading from and writing to files and also controls the creation,

manipulation and access to files.

The operating system is responsible for the following activities in connections with file

management:

� File creation and deletion

� Directory creation and deletion

� Support of primitives for manipulating files and directories

� Mapping files onto secondary storage

� File backup on stable (nonvolatile) storage media

8. Information management: the operating system provides a certain number of indicators that can be used to diagnose the correct operation of the machine.

9. ERROR DETECTION The OS is responsible for detecting and any hardware or software malfunctioning and

reporting them to the user 10. USER/SYSTEM INTERFACE

The OS acts as an interface between the computer and the user, hiding all the

complexities of the computer from the user and making the computer more user

friendly

11. PREPARATION OF A SYSTEM LOG The OS compiles a report on the events that take place in a computer from the time a

user logs on to a computer, what he/she does up to the time he/she logs off

Additional Functions of the operating system:

� Controls and coordinates the computer system


� Scheduling and loading of jobs to provide continuous processing. So that no parts of the

computer system are idle for any significant period of time.

� It is a platform for application programs

� Provides user interface

� Acts as an interface between hardware and application programs

� Provides error correctional routines

� Control over selection and operation of input

� Records details of processing for control analysis

� File management, control the creati

� Memory management, allocates memory to various jobs or tasks

� Multiprogramming, multiprocessing, multitasking, timesharing, housekeeping & handling

errors.

� Resource management manages processor time, memory space, di

peripheral devices.

� Reports errors when they occur.

� Task management. Manage the accomplishment of the computing tasks of end users. It

may involve multitasking capability where several computing tasks can occur at the

same time.

� Minimizes the amount of human intervention required during processing.

COMPUTER INTERFACE

� Refers to the type of interaction between two elements.

� Is part of the operating system that allows you to communicate with it or the computer so

that you can load programs,

� When a person interacts with a computer he uses a User Interface, which can be a screen,

keyboard, mouse, scanners or other input devices.

Definitions of interface on the Web:

• The interaction between the computer abetween a computer and its peripherals.

� Basically the interface can be

� Command driven

provide users with flashes of text and in which users would general

their command to perform an action.

� Menu driven

� GUI- point and click

� WIMP interface

1. Command line interfaces (MSA command line interface allows the user to interact with the computer by

The computer displays a prompt, the user keys in the comman

COMMAND-LINE INTERFACE (CLI)or software by typing commands to perform specific tasks. This text

the use of a mouse pointer with a

text user interface (TUI) to select options.

Features of a command line interface include:

In the early days of personal computers, all PCs used command

• Commands - usually abbreviated command will not work.

• Experienced users who know the commands can work very quickly without having to find

their way around menus.


rrmmmmaakkaahhaa@@ggmmaaiill..ccoomm

Scheduling and loading of jobs to provide continuous processing. So that no parts of the

computer system are idle for any significant period of time.

It is a platform for application programs

an interface between hardware and application programs

Provides error correctional routines

Control over selection and operation of input-output devices & file handling.

Records details of processing for control analysis

File management, control the creation, deletion, saving and access of files

Memory management, allocates memory to various jobs or tasks

Multiprogramming, multiprocessing, multitasking, timesharing, housekeeping & handling

Resource management manages processor time, memory space, disk space and

Reports errors when they occur.

. Manage the accomplishment of the computing tasks of end users. It


amount of human intervention required during processing.

Refers to the type of interaction between two elements.

Is part of the operating system that allows you to communicate with it or the computer so

that you can load programs, access files, and accomplish other tasks?

When a person interacts with a computer he uses a User Interface, which can be a screen,

keyboard, mouse, scanners or other input devices.

on the Web:

The interaction between the computer and the user or the control of the flow of data between a computer and its peripherals.

Basically the interface can be

Command driven- include operating systems and database languages that

provide users with flashes of text and in which users would general

their command to perform an action.

Menu driven

point and click

WIMP interface

Command line interfaces (MS-DOS BASED OPERATING SYSTEM) allows the user to interact with the computer by typing in commands

The computer displays a prompt, the user keys in the command and presses enter or return. A

LINE INTERFACE (CLI) is a mechanism for interacting with a computer operating system

by typing commands to perform specific tasks. This text-only interface contrasts with

with a graphical user interface (GUI) to click on options, or menus on a

to select options.

Features of a command line interface include:

In the early days of personal computers, all PCs used command-line interfaces.

usually abbreviated - must be typed correctly and in the right order or the command will not work.

Experienced users who know the commands can work very quickly without having to find

their way around menus.


62

Scheduling and loading of jobs to provide continuous processing. So that no parts of the

output devices & file handling.

Multiprogramming, multiprocessing, multitasking, timesharing, housekeeping & handling

sk space and

. Manage the accomplishment of the computing tasks of end users. It


Is part of the operating system that allows you to communicate with it or the computer so

When a person interacts with a computer he uses a User Interface, which can be a screen,

nd the user or the control of the flow of data

include operating systems and database languages that

provide users with flashes of text and in which users would generally type in

typing in commands. d and presses enter or return. A

operating system

only interface contrasts with

) to click on options, or menus on a

must be typed correctly and in the right order or the

Experienced users who know the commands can work very quickly without having to find



• An advantage of command driven programs is that they do not need the memory and

processing power of the latest computer and will often run on lower spec machines.

• Command driven programs do not need to run in Windows.

• A command line interface can run many programs, for example a batch file could launch half a dozen programs to do its task.

• An inexperienced user can sometimes find a command driven program difficult to use because of the number of commands that have to be learnt.

An example of a common command-driven interface is MS-DOS, the original operating system for

all Microsoft-compatible PCs. The MS-DOS command to display all files on drive a would be: dir c:\.

2. Graphical user interfaces (WINDOWS BASED OPERATING SYSTEM) Graphical user interface is sometimes shortened to GUI. The user chooses an option usually by pointing a mouse at an icon representing that option. A GRAPHICAL USER INTERFACE (GUI) is a type of user interface item that allows people to interact with programs in more ways than typing such

as computers; hand-held devices such as MP3 Players, Portable Media Players or Gaming devices;

household appliances and office equipment with images rather than text commands. A GUI offers

graphical icons, and visual indicators, as opposed to text-based interfaces, typed command labels

or text navigation to fully represent the information and actions available to a user.

Features of GUIs include:

• They are much easier to use for beginners.

• They enable you to easily exchange information between software using cut and paste or 'drag and drop'.

• They use alot of memory and processing power. It can be slower to use than a CLI if you are an expert user.

• They can be irritating to experienced users when simple tasks require a number of

operations.

When discussing user interfaces, it is important to note that Windows XP, OS/X and Linux are all graphical user interfaces. A good user interface should:

• be attractive and pleasing to the eye

• allow the user to try out different options easily

• be easy to use

• use suitable colours for key areas

• use words that are easy to understand aimed at the type of user

• have online help It also should consider the needs of the users. For example, young children are likely to prefer

pictures to words and people with disabilities may benefit from particular input or output devices

3. WIMP interface • Windows, Icons, Menus and Pointer - a method by which a user can interact with a

computer without having to learn lots of special words - it provides a much more intuitive

'view' of the computer and its facilities than non-WIMP operating systems provide

• "Windows, /images/, Menus and Pointer", or "Windows, /images/, Mouse and Pull-down

menus" This is a graphical interface which makes access to computers much more

straightforward and intuitive than the main alternative, the command-line interface. The


WIMP interface has been used on Apple Macintosh computers since they w

and are coming into use on PCs through Microsoft Windows and on Unix and other

workstations through the X Window system.

4. Menu driven interfaces The user is offered a simple menufurther menu. Part of the screen may have an instruction followed by a numbered list of options to

choose from:

A full screen menu takes up most of the screen.

A menu bar is the set of options at the top of the screen. When an option is chosen a

menu may be offered.

Features of menu driven interfaces include:

• They are easy to use as the user does not have to remember sets of commands.

• They are user friendly - you can often guess your way around the options.

• They can be irritating if there ar

command line interface you can go to the option required immediately.

Dialog box In graphical user interfaces, a dialogto display information to the user, or to get a response if needed. They are so

form a dialog between the computer and the user

requesting input from the user, or both. It provides controls that allow you

out an action. Scrollbar A scrollbar (Also known as a handle in the very first GUIs) is a graphical object in a continuous text, pictures or anything else can b

viewed even if it does not fit into the space in a

Taskbar In computing, taskbar is a desktop display bar used to incorporated a taskbar in Windows 95

graphical user interface ever since. Other

include a taskbar. Other operating systems use terms such as

Toolbar In a graphical user interface on a

buttons, icons, menus or other input or output elements are placed.

WYSIWYG WYSIWYG, is an acronym for What

describe a system in which content displayed during editing appears very similar to the final

output,[2] which might be a printed document, web page, slide presentation or even the lighting

for a theatrical event.

The phrase was originally a catch phrase

(from Rowan & Martin's Laugh-In

would often say "What you see is what you get" to excuse her quirky behavior.

Meaning WYSIWYG implies a user interfaceresult while the document is being created. In general WYSIWYG implies the ability to directly

manipulate the layout of a document without having to type or remember names of layout

commands. The actual meaning depends on the user's perspective, e.g.

• In Presentation programs

display precisely represents the appearance of the pa

does not necessarily reflect how the page will be printed unless the printer is specifically

matched to the editing program, as it was with the

Apple Macintosh.



WIMP interface has been used on Apple Macintosh computers since they were invented,


workstations through the X Window system.

simple menu from which to choose an option. One menu often leads to a

r menu. Part of the screen may have an instruction followed by a numbered list of options to

takes up most of the screen.

is the set of options at the top of the screen. When an option is chosen a

Features of menu driven interfaces include:

They are easy to use as the user does not have to remember sets of commands.

you can often guess your way around the options.

They can be irritating if there are too many levels of menus to move around -

command line interface you can go to the option required immediately.

dialog (or dialogue) box is a special window, used in user interfaces to the user, or to get a response if needed. They are so-called because they

form a dialog between the computer and the user—either informing the user of something, or

requesting input from the user, or both. It provides controls that allow you to specify how to carry

(Also known as a handle in the very first GUIs) is a graphical object in a GUI

continuous text, pictures or anything else can be scrolled including time in video applications, i.e.,

viewed even if it does not fit into the space in a computer display, window, or viewport.

is a desktop display bar used to launch and monitor applications.

Windows 95 and it has been a defining aspect of Microsoft Windows

ever since. Other desktop environments, such as KDE and GNOME

ude a taskbar. Other operating systems use terms such as Panel or Dock.

on a computer monitor a toolbar is a GUI widget on which onscreen buttons, icons, menus or other input or output elements are placed.

hat You See Is What You Get. The term is used in computing


which might be a printed document, web page, slide presentation or even the lighting

catch phrase popularized by Flip Wilson's drag persona "Geraldine"

In in the late 60s and then on The Flip Wilson Show until 1974), who

en say "What you see is what you get" to excuse her quirky behavior.

user interface that allows the user to view something very similar to the end is being created. In general WYSIWYG implies the ability to directly

of a document without having to type or remember names of layout

commands. The actual meaning depends on the user's perspective, e.g.

Presentation programs, Compound documents and web pages, WYSIWYG means the

display precisely represents the appearance of the page displayed to the end


matched to the editing program, as it was with the Xerox Star and early versions of the


64

ere invented,


from which to choose an option. One menu often leads to a

r menu. Part of the screen may have an instruction followed by a numbered list of options to

is the set of options at the top of the screen. When an option is chosen a pull down

They are easy to use as the user does not have to remember sets of commands.

- with a

, used in user interfaces

called because they

either informing the user of something, or

to specify how to carry

GUI with which

including time in video applications, i.e.,

, or viewport.

launch and monitor applications. Microsoft

Microsoft Windows's

GNOME, also

on which onscreen

computing to


which might be a printed document, web page, slide presentation or even the lighting

"Geraldine"

until 1974), who

that allows the user to view something very similar to the end is being created. In general WYSIWYG implies the ability to directly

of a document without having to type or remember names of layout

, WYSIWYG means the

ge displayed to the end-user, but


and early versions of the


• In Word Processing and

simulates the appearance and precisely represents the effect of fonts and line breaks on

the final pagination using a specific

500-page document can accurately refer to a reference three hundred pages later.

• WYSIWYG also describes ways to manipulate 3D models in aided design, 3D computer graphics

design tool used in the theatre industry for pre

Menu bar A menu bar is a region where computer menus

application-specific menus which provide access to such functions as opening files, interacting

with an application, or help. Menu bars are typically present in windows.

Menu bar from Mozilla Firefox.

SYSTEM SOFTWARE- consists of programs that manage and support a computer system and its

information processing activities. T

computer system hardware and the application programs of end users.

System software is computer software

provide a platform for running a

The most basic types of system software are:

• The computer BIOS and device control the hardware connected to or built into the computer.

• The operating system (prominent examples being Linux), which allows the parts of a computer to work together by performing tasks like

transferring data between

also provides a platform to run high

• Utility software, which helps to analyze, configure, optimize and maintain the computer.In some publications, the term system software

tools (like a compiler, linker or debugger

Computer purchasers seldom buy a computer primarily because of its system software. Rather,

system software serves as a useful (even necessary) level of infrastructure code, generally built

pre-installed.

In contrast to system software, software that allows

play games, listen to music, or surf the web is called

Types of system software programsSystem software helps use the operating system and computer system. It includes diagnostic tools,

compilers, servers, windowing systems, utilities, language translator, data communication

programs, database systems and more. The purpose of system software

applications programmer as much as possible from the complexity and specific details of the

particular computer being used, especially memory and other hardware features, and such

accessory devices as communications, printers, readers, d

Specific kinds of system software include:

• Loaders

• Linkers

• Utility software

• Desktop environment / Graphical user interface

• Shells



In Word Processing and Desktop Publishing applications, WYSIWYG means the display


the final pagination using a specific printer configuration, so that a citation on page 1 of a

page document can accurately refer to a reference three hundred pages later.

WYSIWYG also describes ways to manipulate 3D models in Stereochemistry, Computer3D computer graphics and is the brand name of Cast Software's lighting

used in the theatre industry for pre-visualisation of shows.

computer menus are housed. Its purpose is to house window

specific menus which provide access to such functions as opening files, interacting

n, or help. Menu bars are typically present in graphical user interfaces

consists of programs that manage and support a computer system and its

information processing activities. These programs serve as a vital software interface between

computer system hardware and the application programs of end users.

computer software designed to operate the computer hardware and to

application software.

The most basic types of system software are:

and device firmware, which provide basic functionality to operate and control the hardware connected to or built into the computer.

(prominent examples being Microsoft Windows, Mac OS X), which allows the parts of a computer to work together by performing tasks like

between memory and disks or rendering output onto a display device

a platform to run high-level system software and application software

, which helps to analyze, configure, optimize and maintain the computer.system software is also used to designate software develop

debugger).

purchasers seldom buy a computer primarily because of its system software. Rather,

system software serves as a useful (even necessary) level of infrastructure code, generally built

In contrast to system software, software that allows users to do things like create text documents,

play games, listen to music, or surf the web is called application software.

Types of system software programs System software helps use the operating system and computer system. It includes diagnostic tools,


programs, database systems and more. The purpose of system software is to insulate the



accessory devices as communications, printers, readers, displays, keyboards, etc.

Specific kinds of system software include:

Graphical user interface


65

WYSIWYG means the display


, so that a citation on page 1 of a

page document can accurately refer to a reference three hundred pages later.

Computer-Cast Software's lighting

are housed. Its purpose is to house window- or

specific menus which provide access to such functions as opening files, interacting

graphical user interfaces with

consists of programs that manage and support a computer system and its

hese programs serve as a vital software interface between

and to

onality to operate and

Mac OS X and ), which allows the parts of a computer to work together by performing tasks like

display device. It

application software.

, which helps to analyze, configure, optimize and maintain the computer. software development

purchasers seldom buy a computer primarily because of its system software. Rather,

system software serves as a useful (even necessary) level of infrastructure code, generally built-in or

users to do things like create text documents,

System software helps use the operating system and computer system. It includes diagnostic tools,


is to insulate the





• BIOS

• Hypervisors

• Boot loaders

• Database Management Systems(SQL, NoSQL)

If system software is stored on non-volatile memory such as integrated circuits, it is usually termed firmware.

3 functional categories of system software

System management programs � Programs that manage the hardware, software, and data resources of

the computer system during its execution of the various information

processing jobs of users.

� The most important system management programs are operating systems

and operating environments, followed by telecommunications monitors &

Database Management Systems.

System support programs � Programs that support the operations and management of a computer

system by providing a variety of support services.

� Major support programs are system utilities, performance monitors, &

security monitors.

System development programs � Programs that help users develop information system programs

and procedures and prepare user programs for computer

processing.

� Major development programs are language translators,

programming tools and CASE [computer-aided software engineering] packages.

APPLICATION PACKAGES/SOFTWARE

� Are programs that are or were developed to solve specific user problems?

� Word processors and spreadsheets fall into this category.

� Software application packages can be custom built or they can be bought off the shelf.

# APPLICATION SOFTWARE

DESCRIPTION EXAMPLES

1 Word processing software

• A word processor is used to produce documents such as letters,

memos and reports. The latest versions of word processing software

contain many features and can also be used for "desktop publishing"

to create newsletters, brochures, business cards, signs and more. The

latest word processing software will allow you to easily type into

columns, add pictures and charts to your page, create custom

borders, and experiment with a variety of type faces (fonts) in a wide

range of sizes. You can even combine different fonts on the same

page.

• Word processing software offers many exciting formatting and editing

features to make your work easier. You can easily check the spelling of

a word or the entire document. The built in thesaurus will help you find

an alternate word to use. Blocks of text can be easily moved, copied

or erased.

• Use this kind of tool to create worksheets, type letters, type papers,

etc, e.g. MS Word, WordPerfect,....

• Ms word,

Word

perfect,

Word star,

• Ms works

word

processor

,WordPro

2 Spreadsheet software

• A spreadsheet is used to manage, analyze and present numeric

information. Some common uses of spreadsheet software are financial

reports, personal finances and business finances. Spreadsheet

programs can also create a chart from the numeric data.

• Ms Excel,

Lotus 1-2-3



• The working screen is laid out in rows and columns, much like a ledger.

The information is typed into a "cell." A cell is the intersection of a row and a column. The cell can contain a number, a word or phrase

(generally used to identify what the number represents, such as a

column or row heading), or a math function or formula.

• Spreadsheets allow you to use simple math expressions such as add,

subtract, multiply or divide, or advanced math such as the type of

calculations performed by architects, engineers, economists and

scientists. Spreadsheets also have a special group of built-in formulas,

called functions, that let you perform calculations without having to

type long, complex formulas. Functions are grouped into categories,

such as financial, statistical, engineering, logical, math and

trigonometry, database and list management, date and time, and

information.

• One of the reasons many people use a computer for their spreadsheet

projects is because it is easy to change your information once it has

been entered. If you change a number, the spreadsheet will

automatically recalculate the results. You can also take advantage of

this feature to perform a "what-if" analysis. For example, you input the

data for a small business venture you are considering and the

spreadsheet calculates your net profit for the first year of business. If

you are not pleased with the result, you can change a few numbers to

see how the change would affect the outcome.

• Use this kind of tool to compute number-intensive problems such as budgeting, forecasting, etc. A spreadsheet will plot nice graphs very

easily, e.g. MS Excel, Quattro Pro, Lotus 1-2-3,

3 Database management software

• Allows user to prepare reports based on data found in different records. DBMS is an important managerial decision support tool for

managers at all levels of the organization. A database is an organised

store of information, for example an address book, list of employees,

list of students, customers or items of assets. Database package is used

to store records. Data can be sorted or filtered for separate viewing.

Also Calculations and comparisons between data items can be done.

Popular database packages are: Microsoft Excel, lotus Approach,

Paradox, dBase IV, Data Ease. • Use this software to store data such as address, membership and other

text information. A database can be used to easily sort and organize

records

• Ms Access,

DbaseIV,

Oracle

4 Payroll • Pay plus ,

Pay well

5 Accounting e.g. Pastel, TurboCash, QuickBooks • Pastel,

Tetra 2000

6 Presentation graphics software

• Lets users or managers prepare slides containing charts, text and

images. Presentation graphics software usually provides libraries of clip

art images that can be cut and pasted into a slide to make the slide

more attractive and informative. These are applications designed

solely for designing graphs and text charts/posters and often used to

produce slides for use on overhead projectors, or presentations on

computer-projectors. They can also produce various types of charts.

Examples of graphics packages are: Microsoft PowerPoint, Lotus

Freelance, Harvard Graphics and Corel Draw, HyperStudio, Flash,

Director.

• Use this software to create multimedia stacks of cards/screens that

can effectively present a lesson or a sales pitch. The user often clicks

• Ms

PowerPoin

t, Lotus

freelance

graphs



on buttons to advance to the next screen in a sequence

7 Desktop Publishing

• Use this software to make signs, banners, greeting cards, illustrative

worksheets, newsletters, etc • Desktop Publishing (DTP) applications give users powerful and versatile

page design capabilities. The user can incorporate text and graphics

on very exact page layouts. These applications produce magazines,

catalogues, invitation cards, business cards and other sophisticated

documents. It links up well with other applications as the user can

import text and graphics from the other applications. Examples of DTP

packages are: Microsoft Publisher, PageMaker, Ventura and Frame

maker.

• Ms

publisher, Aldus

8 Multimedia i) Internet Browsers This software allows one to surf the Web. Often they can read email and

create Web pages too, e.g. Netscape Navigator (or Netscape

Communicator), MS Internet Explorer, AOL Browser....

ii) Email programs These programs send and receive email, e.g. Netscape Messenger (part of

Netscape Communicator), MS Outlook Express, MS Outlook, Eudora, AOL

browser (has email built in)....

iii) Graphics Programs (pixel-based) This software allows one to touch up photographs and create graphics

from scratch, e.g Adobe Photoshop, Paint Shop Pro, MS Paint (comes free

on Windows PC's), Painter, ....

• Internet

explorer

Netscape

9 Communication • This software allows two computers with modems to communicate

through audio, video, and/or chat-based means, e.g. MS NetMeeting,

AOL Instant Messenger, IRC, ICQ, CU-SeeMe, ...

• Ms

Outlook,

Ms

Exchange

10 Design e.g. AutoCad, Corel Draw • AutoCAD,

CAM

State five advantages of using a word processor (e.g. MS Word) rather than a manual typewriter in an office [10].

� Ability to correct mistakes

� Ability to view documents on screen before printing

� Ability to incorporate diagrams � Ability to move parts of text to other sections of the document.

� Ability to save or store documents for future reference or use.

� Ability to alter or change document layout.

� Ability to print a lot of copies [ no retyping]

� Ability to insert tables

� Ability to format document [font, paragraphs, bullets etc] Spelling and grammar checker

� Import files

� Mail merge

� WYSIWYG capability

� Creation of templates

� Automatic creation of index and table of contents

o ther - Good reasoning [ 2 marks each for 5 & 1 mark each for more than 5]

a) Explain what is meant by the term ‘word processing package’. [3 marks]



� Is a program or set of programs used to enter, edit, format, store and print

documents. A document may be anything from a single memo to a complete

book.

� An application package that involves the use of computers to manipulate

text data in order to produce office communications in the form of

documents.

� Any of many popular application programs designed for composing, revising,

printing, and filing written documents.

� Word Processing is the efficient and effective production of written communications at the lowest possible cost through the combined use of

systems management procedures, automated technology, and

accomplished personnel. The equipment used in word processing

applications includes but is not limited to the following: dictation and

transcription equipment, automatic repetitive typewriters, visual display text

editing typewriters, keyboard terminals, etc.

b) Give any 2 examples of a word processing package’. [2marks] � MS WORD

� WORD STAR

� WORD Perfect

� MS WORKS WORD

c) Briefly describe any 5 important features of a word processor. [5 marks] 1) Spelling and grammar checker

2) Import files

3) Mail merge

4) WYSIWYG capability

5) Creation of templates

6) Automatic creation of index and table of contents

d) List any 10 facilities that spreadsheets offer. [10 marks] 1. Format cells, rows and columns, specifying for example, the alignment of text, number

of decimal points, height and width of a cell.

2. Copy cell contents to other locations

3. Determine the effect of several different hypothetical changes of data

4. Insert, move or delete rows and columns

5. Use functions such as SUM, AVERAGE, MAX, MIN in formulae

6. Create a simple database and sort or query the data to produce a report

7. Write macros to automate common procedures

8. Create templates i.e. spreadsheets with formats and formulae already entered, into

which new figures may be inserted.

9. Create multi-dimensional spreadsheets using several sheets, and copy data from one

sheet to another

10. Create many different types of charts and graphs

Shortcomings of spreadsheets While spreadsheets are a great step forward in quantitative modeling, they have deficiencies. At

the level of overall user benefits, spreadsheets have four main shortcomings.

• Spreadsheets have significant reliability problems. Research studies estimate that roughly 94% of spreadsheets deployed in the field contain errors, and 5.2% of cells in unaudited

spreadsheets contain errors.

• The practical expressiveness of spreadsheets is limited. Several factors contribute to this limitation. Implementing a complex model requires implementing detailed layouts, cell-at-

a-time. Authors have difficulty remembering the meanings of hundreds or thousands of cell

addresses that appear in formulas.

• Collaboration in authoring spreadsheet formulas is difficult because such collaboration must occur at the level of cells and cell addresses. By comparison, programming



languages aggregate cells with similar meaning into indexed variables with names that

indicate meaning. Although some spreadsheets have good collaboration features,

authoring at the level of cells and cell formulas remains a significant obstacle to

collaboration in authoring spreadsheet models. On the other hand, many people

collaborate on entering numerical data and many people can use the same spreadsheet.

• Productivity of spreadsheet modelers is reduced by the cell-level focus of spreadsheets. Even conceptually simple changes in spreadsheets (such as changing starting or ending

time or time grain, adding new members or a level of hierarchy to a dimension, or

changing one conceptual formula that is represented as hundreds of cell formulas) often

require large numbers of manual cell-level operations (such as inserting or deleting

cells/rows/columns, editing and copying formulas, re-laying out worksheets). Each of these

manual corrections increases the risk of introducing further mistakes.

These four deficiencies in high-level benefits have deeper causes that, ironically, flow directly from

the signature strength of spreadsheets (that they capture the structure of models in terms of

WYSIWYG sheet layout for authors and report users).

• Spreadsheets capture model logic in terms of sheet layout, especially contiguous layout of cells in a table. Spreadsheets have weak or nonexistent methods to capture higher level

structures such as named variables, segmentation dimensions, and time series.

• Formulas are subordinated to the cell layout. This forces the sheet layout to carry the

structure of the model, not variables and formulas that relate variables. This also causes a large proliferation of cells, formulas and cell-level tasks even when only a few basic

concepts are involved in a model. This forces authors to think and work at the level of cells

instead of at the level of the natural concepts and structures of the model.

• Formulas expressed in terms of cell addresses are hard to keep straight and hard to audit.

Research shows that spreadsheet auditors who check numerical results and cell formulas

find no more errors than auditors who only check numerical results.

• Proliferation of error-prone manual cell-level operations contributes to all four of the high-level problems listed above.

Criteria for Selecting Applications Software:

• Accuracy - it must be free from errors

• Flexibility – it must be able to adapt to changing environment.

• Compatibility - it must be compatible with available hardware and software

• Recency - it must be current • Cost - it must have reasonable cost

• Originality - It must be original

• Support - consider continued support from the supplier.

• Ease of use - it must be user friendly.

• Performance - it must have efficiency in both response time and run time.

• Memory requirements

Factors to consider when buying application software

1. Cost. This includes the original cost of the package, technical support, and upgrades. 2. Portability, can it be installed on one type of hardware or a variety 3. Relevance of the software to the task at hand. 4. Compatibility with existing hardware & software. Will the package run on existing

hardware? Can files be easily transferred from existing systems without re-keying? Can

files created in the package be exported to other systems in use in the company?

5. It should be on a media compatible with your computer i.e. if you purchase software on CD media your computer should have compact disk drive.

6. Sophistication, simple programs are usually easy to learn, cost less and are appropriate for

those who use the software infrequently.

7. Should include enough documentation such as installation instructions, system

requirements e.g. Pentium 4, reference manual, registration information, supplier details

and user manual.



8. Standard software, which is well supported locally i.e. used by most people in that area 9. Is the application upgradeable and does it support future upgrades. 10. Easiness of installation 11. Technical support. Is support available? Is it very costly? Often, technical support contract

can add 50% or more to the price of a package, but without it no support at all will be

given by the manufacturer. 12. Easy of learning. Are tutorials supplied? Are books on the software available in

bookshops? Are training courses available? 13. Easy of use and user- friendliness. Is it easy to use, for example using pull down menus,

icons, helpful error messages when you do something wrong?

14. Is the application from a reputable supplier e.g. Microsoft.

15. Do you have enough resourceson your PC to install it e.g. it may require 256MB RAM,

80GB HDD. Memory requirements; software packages vary in the amount of memory they

require. Will the system require expenditure on more powerful hardware?

16. Does the version of the product that I am considering run on my personalcomputer system? Is it compatible with my platform (PC, Macintosh, Sun, and so on)? with the

processor used in my computer (486, Pentium, Motorola 6040, PowerPC, and so on)? and

with the operating system that I am running (DOS, Windows, NeXT Step, UNIX)?

17. Is the product compatible with other programs, such as extensions and device drivers, that I have on my personalcomputer system?

18. Does the product do all that I want it to do? Is it simple enough to use immediately but powerful enough to provide the capabilities that I will want as my familiarity with the

program increases?

19. Is the product an up-to-date, current version or release? 20. Does the product have a clear, step-by-step tutorial? Is the product easy to learn? 21. Is the product accompanied by clear, easy-to-follow instructions, or documentation? 22. Does the manufacturer provide technical assistance? Is a toll-free technical assistance

number included in the software documentation? Does the manufacturer have a bulletin

board or Internet address for technical assistance questions? Does the manufacturer

charge for technical assistance? for product revisions or upgrades?

23. Can I find instruction, or training, in the use of the product? 24. Is the product from a respected, well known manufacturer? 25. Does the program have any known problems, or bugs, and will these affect my use of the

program?

26. Does the product come with a warranty, and what are the conditions of that warranty? 27. Does the product cost more or less than comparable products on the market?

Benefits of application software to the user.

� Installation should be easy, quick and should be provided by the vendor/supplier.

� Good documentation is usually provided with the application for reference

purposes.

� Onsite assistance from the supplier or vendor

� Provision of cheaper future upgrades upon acquisition of an application provided you have completed the registration information.

� Value for money

Applications software comes in different 'flavors' - or types: • Utility programs - these can be part of an operating system, but are also available for

separate purchase. Examples include virus checkers, disk defragmenters, back up utilities

and disk checker software.

• Generic - general purpose software that is not written for any particular type of business. Examples of this include word processors and spreadsheets.

• Integrated - a collection of software that has a common set of commands/icons. Usually they include word processors, spreadsheets and graphics software, but they can contain

databases as well. They tend to be cheaper than purchasing each application separately. • Specific - software written for a defined purpose. Accountancy software is a good

example of this, and can be bought by anyone.



• Bespoke - also known as 'tailor made'. A company may need a particular piece of

software that it cannot purchase because it does not exist yet - or it does not like what is available. The company can commission the software to be specially written for them. This

tends to be expensive.

SOURCES OF SOFTWARE

1. Freeware o Freeware is the type of freely available software whose developer decides to distribute it

for free. In contrast to the open source software, the source code in this case is not

available for modifications and further development. Also, it should be noted that the

distribution of the software may also be restricted by its developer, often allowing users to

download it from his site only. Many free to download applications are available on the

Internet. It is always wise to read the license before downloading the software. Many

people tend to unknowingly share such applications with other people, without realizing

that this may actually be illegal.

2. Shareware o Shareware is very different from these other forms of free software and to some extent also

a misnomer. The authors of shareware maintain their full intellectual right over shareware.

The only difference between shareware and other commercially available software is that

in this case the software is available for freely for trial for a limited number of days, or a

limited number of times. After the expiry of the ‘free’ period, the users of shareware are

required to pay for it. Source code and collaboration communities which exist around

open source projects do not exist in this case.

3. Off-the –shelf/generic or Commercial Software

4. In-house/Custom made/Tailor Made/Bespoke software

5. Outsourcing This involves contracting out software development to a software house - better known as

outsourcing, especially where off-the-shelf packages are not available. Advantages

o Software houses employ professionals and this may benefit the organisation

o Transfer of skills to the existing professionals in an organisation

o Organisation can get support from the contractor.

Disadvantages

o There could be breach of confidentiality.

o Contractor may go bankrupt and cease trading leaving the user with no support.

o Contractor might not have sufficient experience or understanding of the problem;

thus the solution might not be satisfactory.

o It takes time for the contractor to understand the user's business and operations,

which makes the approach expensive.

CLASSIFICATION OF SOFTWARE APPLICATIONS

1. Commercial / generic Packages/Off the shelf software • Commercial software is computer software sold for profit; such software

represented, until recently, the vast majority of all software used.

• These are bought from a vendor.

• Also known as off the shelf packages e.g. MS Office, Pastel.

• Also known as work enhancement applications

• Generic or Off the shelf software has the advantage of cost effectiveness due to larger market & the ability to incorporate available technology in the shortest

possible time.



These increase the productivity & efficiency in the work place i.e.

o Word Processing packages

o Spreadsheet packages

o Database /Information retrieval Packages

o Graphics packages

o Data communications Software

• Off-the –shelf/generic or Commercial Software

This is software that can be purchased, from a software company that develops programs

and sells them to many computer users and organizations. Applications such as financial

accounting, business graphics and pay roll may be bought.

Advantages

o Cheaper - the software company is able to spread the software development cost

over a large number of customers, hence reducing the cost any one customer must

pay.

o Less risky - the software is in existence, hence you can analyse the features and

performance of the package.

o The program is a well-tried and tested product with few errors. o Less time - Off-the -shelf software is often installed quickly and easily.

o The package is well documented

o The packages require little maintenance

o There is continued support from the supplier through upgrades.

o It is cheaper than custom-written software. The development costs of the package

may be millions of pounds, but the customer may be able to buy it for a few hundred

pounds, since sales are made to thousands of other customers.

o It is immediately available and already thoroughly tested so is unlikely to have major

bugs in it

o Documentation is usually available in the form of reference manuals, user guides and

tutorials

o Training courses may be available form third party trainers.

o Technical support is usually available from the manufacturers via a Web site or

telephone line [at a price].

o Other users of the package can be consulted as to its suitability before purchase.

o Upgrades are usually available every year or two

Disadvantages

o The package may not do exactly what you want it to do;

o It may not run on the firm’s existing hardware

o It may not interface with other software already in use in the organization.

o The organization might need to pay for the features that are not required and

never used.

o The package may be for general needs and therefore not ideal for the user.

o The user has no direct control over the package,

2. Homemade / Customized packages/ Tailor-made Software

� Customized software is software designed around a company or other organization's

processes to make those processes more efficient. � It is distinct from market software [commercial or generic], which approaches

problems in a general way so that the product can be sold to more than one

customer.



� Has been written by the vendor specifically for a user’s needs. Also known as in-house

packages, tailor-made packages.

� E.g. most payroll packages, billing software, product design applications

� Is that application that has been written for a specific user’s needs by a software

vendor?

� It is non-standard software.

• In-house/Custom made/Tailor Made/Bespoke software This approach requires a development team from within the organisation. The team is

usually comprised of programmers and analysts. The team members should be of high

calibre, highly trained and reliable.

Advantages

o Internal professionals understand operations better and therefore can produce an

accurate solution.

o The Software usually meets user requirements.

o Management are in total control of the development process

o More flexibility - there is more flexibility in making modifications.

o Problem specificity - in-house developed software can give an organisation

software programmes that are easily tailored to a unique problem or task.

Disadvantages

� Time and costs of developing the program may be greater than other options

� In-house staff may lack the expertise needed for the project

� Reliability of the resultant software is highly questionable.

� In some cases the developers may attempt to gain fraudulently from the system

�

Disadvantages 1. Being customized, the non-standard software may not be used by any other organization. 2. It has huge support costs after implementation. 3. Dependency syndrome with the supplier. There is heavy reliance on the developers of the

software for its continued existence & maintenance

4. Future support may be difficult if the supplying company goes under, shuts down, or

liquidate or if its development staff leaves. 5. May not be upgradeable and may not run if moved to a new hardware platform. 6. You are tied to a supplier of which you may not be willing to have a maintenance

contract with. 7. Written or Custom-built software performs a defined function and is expensive to build.

8. Custom built is expensive to maintain

9. Custom built software has reduced lifespan due to high speed of technological

advancement in the field of computers.

3. Managerial applications Help to make management decisions

� Decision support systems � Database Management Systems Report Writing Tools

MAKE NOTES ON:

� How application packages solve problems? � Typical problems which can be solved by application packages � Customization of packages using macros

Utility software Utility software (also known as service program, service routine, tool, or utility routine) is computer

software designed to help manage and tune the computer hardware, operating system or

application software by performing a single task or a small range of tasks. Some utility software has

been integrated into most major operating systems.

Examples • Disk storage utilities

•



o Disk defragmenters can detect computer files whose contents are broken across

several locations on the hard disk, and move the fragments to one location to

increase efficiency.

o Disk checkers can scan the contents of a hard disk to find files or areas that are corrupted in some way, or were not correctly saved, and eliminate them for a

more efficiently operating hard drive.

o Disk cleaners can find files that are unnecessary to computer operation, or take

up considerable amounts of space. Disk cleaner helps the user to decide what to

delete when their hard disk is full.

o Disk space analyzers for the visualization of disk space usage by getting the size for each folder (including subfolders) & files in folder or drive. showing the

distribution of the used space.

o Disk partitioners can divide an individual drive into multiple logical drives, each

with its own filesystem which can be mounted by the operating system and

treated as an individual drive.

o Backup utilities can make a copy of all information stored on a disk, and restore

either the entire disk (e.g. in an event of disk failure) or selected files (e.g. in an

event of accidental deletion).

o Disk compression utilities can transparently compress/uncompress the contents of

a disk, increasing the capacity of the disk. o File managers provide a convenient method of performing routine data

management tasks, such as deleting, renaming, cataloging, uncataloging,

moving, copying, merging, generating and modifying data sets.

o Archive utilities output a stream or a single file when provided with a directory or a

set of files. Archive utilities, unlike archive suites, usually do not include compression

or encryption capabilities. Some archive utilities may even have a separate un-

archive utility for the reverse operation.

• System profilers provide detailed information about the software installed and hardware attached to the computer.

• Anti-virus utilities scan for computer viruses.

• Text and Hex Editors directly modify the text or data of a file. These files could be data or an actual program.

• Data compression utilities output a shorter stream or a smaller file when provided with a stream or file.

• Cryptographic utilities encrypt and decrypt streams and files.

• Launcher applications provide a convenient access point for application software. • Registry cleaners clean and optimize the Windows registry by removing old registry keys

that are no longer in use.

• Network managers check the computer's network, log events and check data transfer.

• Command line interface (CLI) and Graphical user interface (GUI) Allows the user to contact and make changes to the operating system.

INTEGRATED SOFTWARE

� Integrated software is software for personal computers that combines the most commonly

used functions of many productivity software programs into one application. � The integrated software genre has been largely overshadowed by fully functional office

suites, most notably Microsoft Office, but at one time was considered the "killer

application" type responsible for the rise and dominance of the IBM PC in the desktop

business computing world.

� In the early days of the PC before GUIs became common, user interfaces were text-only

and were operated mostly by function key and modifier key sequences. Every program

used a different set of keystrokes, making it difficult for a user to master more than one or

two programs. Programs were loaded from floppy disk, making it very slow and

inconvenient to switch between programs and difficult or impossible to exchange data

between them (to transfer the results from a spreadsheet to a word processor document

for example). In response to these limitations, vendors created multifunction "integrated"



packages, eliminating the need to switch between programs and presenting the user with

a more consistent interface.

� The potential for greater ease-of-use made integrated software attractive to home

markets as well as business, and packages such as the original AppleWorks for the Apple II

and Jane for the Commodore 128 were developed in the 1980s to run on most popular

home computers of the day.

� Context MBA was an early example of the genre, and featured spreadsheet, database,

chart-making, word processing and terminal emulation functions. However, because it

was written in Pascal for portability, it ran slowly on the relatively underpowered systems of

the day. Lotus 1-2-3, which followed it, had fewer functions but was written in assembler,

providing it with a speed advantage that allowed it to become the predominant business

application for personal computers.[2]

� The integrated software market of today is exemplified by entry-level programs such as

Microsoft Works which are often bundled with personal computers as "starter" productivity

suites.

SOFTWARE SUITES/BUNDLED SOFTWARE • A software suite or application suite is a collection of computer programs, usually

application software and programming software of related functionality, often sharing a

more-or-less common user interface and some ability to smoothly exchange data with each other.

• Sometimes software makers introduce "suites" that are little more than repackaged

versions of older programs offered at a lower price.

• The solution might be "software suites" or "bundled software." A "suite" is a collection of the

full-featured versions of each software application - word processing, spreadsheet,

database management, graphics, communications and sometimes organizers.

• These applications are from the same software manufacturer and are packaged together

in a large box and sold at prices that are much lower than if they were purchased

individually - usually less than half of the original collective price! The software applications

contained in a suite or bundle are the same applications a professional user might

purchase individually. No corners have been cut, and additional features may have been

added such as a "common interface" that allows any of the programs to be accessed

from the same "main menu," a consistent screen layout used by each of the programs,

and the ability to easily exchange data from one program to another.

INTEGRATED SOFTWARE/BUNDLED SOFTWARE / SOFTWARE SUITE

� SOFTWARE that contains several applications rolled into one.Integrated software usually includes word processing, spreadsheet, database, graphics and communication capabilities. Two popular Integrated softwarepackages are Microsoft Works and ClarisWorks:

� In integrated software, you will be able to work on a spreadsheet to perform calculations, store addresses and phone numbers in a database and be able to link information from

the spreadsheet & the database when you work with the word processor in the integrated

package.

� Object Linking Embedding [OLE] is a standard that, Allows applications to be linked

together.

� OLE-DB allows applications to import virtually any form of data into the database.

Definitions of integrated software on the Web:

• A group of applications designed to work together and share data easily. Software that combines the features of several different applications in a single program

(e.g. word processing, database, spreadsheet, graphics, and communications)..

Advantages of integrated applications

� Easy to use

� Generally costs much less



� Require or needs less RAM

� Ability to pass data from one module to another.

� Takes up much less hard disk space

� Better organization of information. Data is stored in the database, calculations in an

electronic spreadsheet & images in a graphical application package

The advantages of bundled software suites are

• Low cost compared to buying each application separately

• Option to install all of the programs at the same time or only the programs you want to use

• Consistent interface from one application to another

• The ability to share information between applications

• Future upgrades can update each application all at the same time

• Ideal for personal use, professional use, large or small business

• Each application is the full-featured version

The disadvantages are • High initial cost

• All applications are from the same manufacturer - you might prefer a word processor from

one company, a spreadsheet from a different manufacturer, etc.

• May be purchasing more software than you actually need

• Installation of the entire suite of applications takes up a large amount of storage space on

your internal hard disk

• Several large manuals to study if you plan to master each application, or the package

might not include printed manuals in order to keep the cost low

Disadvantages

� Limited portability. The same applications must exist on every computer that you wish to

open the document.

� Offer fewer features and less versatility than stand alone versions or software.

� Functional limitation. Its rigid you cannot change it to suit your specific needs.

EXAMPLES OF INTEGRATED SOFTWARE

• Microsoft Office 97 • Microsoft Works

• Claris Works

• Lotus SmartSuite 97

• Microsoft Office 2003,2007,2010 & 2013

OPEN SOURCE SOFTWARE

• Open source is a type of software which is freely available and its source code is available

for further development, modification. Generally all open source software have a

community of developers who provide support, documentation and even binary versions

of the software to people who may be interested in it. These additional services, though,

may not be free monetarily.

• There are several ongoing open source software projects. The open source nature of these

projects means that there will be several people working on modifying and improving the

software from around the world. Some such examples include the Web browser Mozilla

Firefox, content management software like Drupal, Joomla etc.

SOFTWARE COPYRIGHT

The Copyright, Designs and Patents Act



Copyright is a legal concept, giving the creator of an original work exclusive rights to control its

distribution for a certain time period.

Copying computer software is therefore a breach of copyright and a criminal offence. The Act

covers stealing software, using illegally copied software and manuals, and running purchased

software on more machines than the license allows.

The legal penalties for breaking the copyright law include unlimited fines and up to two years in

prison.

All the software that you use should be fully licensed. When you purchase software you usually are

licensed to use it on just one computer. It is illegal to make copies of the software to use on other

computers, even if they are your own.

Software licences can be:

• Single user - licensed for installation on one computer

• Multi-user - the license allows you to install the software on a named number of computers

• Site-licence - the licence lets you install the software onto an unlimited number of computers, as long as they are on one distinct site such as a school

Software protection

Software companies try to prevent illegal copying of their disks using the following methods:

• Copy protection - the disk (or CD-Rom) may be formatted in a special way so it cannot easily be copied.

• Restricting the number of installations - each installation is recorded on an installation disk and only a certain number are allowed.

• A registration key - a unique series of letters and numbers that is asked for when running

the program. The software will not run if the registration key is not typed in correctly and

online multiplayer games will not to run if another user is online who has used the same key.

• A phone or Internet activation code - this requires the user to call a number or go online to register the product. They then receive a unique computer-specific serial number.

• Encryption - data can be scrambled up and cannot be read without the correct software.

• A Dongle - a piece of hardware that must be plugged into the computer to run the

software. Each one contains a unique electronic serial number and as they are expensive

to produce they are mostly used to protect high-end software packages.

• Details of the user are built into the software - when the software is run it displays the original users name. This does not prevent the copying but it makes is obvious that the

copy is illegal.

• A Keyfile - a small file with a unique code that is placed in the same directory as the program. If the code is not valid then the software will not run.

SOFTWARE PIRACY � Unauthorized copying of software.

� unauthorized use or reproduction of copyrighted patented material.

� unauthorized copying of software

� The production of illegal copies of software.

� By far, the biggest legal problem affecting the computer industry today is software piracy,

which is the illegal copying or use of programs. Piracy is a huge problem mainly because

it is so easy to do. In most cases, it is no more difficult to steal a program than it is to tape

a music CD that you have borrowed from a friend. Software pirates give up the right to



receive upgrades and technical support, but they gain the use of the program without

paying for it.

Implications of Software piracy � Loss of business to software companies.

� Lack of technical support, no connection with supplier upgrades.

� Software incompatibility, may require a key, which you might not have, as a result

you can’t install it.

� Virus Spread

� Lawsuits for copyright, which may be very costly in terms of reputation and money.

� Piracy harms all software publishers, Regardless of their size. Software publishers spend years developing software for the public to use. A portion of every dollar

spent in purchasing original software is channeled back into research and

development so that better, more advanced software products can be produced.

When you purchase pirated software, your money goes directly into the pockets of

software pirates instead.

� Software piracy also harms the local and national economies. Fewer legitimate

software sales result in lost tax revenue and decreased employment. Software piracy

greatly hinders the development of local software communities. If software

publishers cannot sell their products in the legitimate market, they have no incentive

to continue developing programs. Many software publishers simply won’t enter markets where the piracy rates are too high, because they will not be able to

recover their development costs.

� Software piracy harms everyone in the software community including you, the end user. How?

1) Piracy results in higher prices for duly licensed users,

2) Piracy reduces levels of support, and

3) Delays in the funding and development of new products, causing the overall

selection and quality of software to suffer.

THE DIFFERENT TYPES OF SOFTWARE PIRACY There are five basic forms of software piracy, and all are damaging both to the software publisher

and to you, the end user. The five basic types of piracy are:

• Soft lifting. This form of piracy occurs when extra copies of a program are made within an organization for employees to use. It also includes "Disk swapping" among friends and

associates.

• Hard-Disk Loading. Some computer dealers load unauthorized copies of software onto the hard disks of the computers they offer for sale, as an incentive for an end user to purchase a

computer from that particular dealer.

• Counterfeiting. This is the illegal duplication and sale of copyrighted software, often in a form

designed to make the product appear legitimate. Software counterfeiting can be very

sophisticated, including significant efforts to replicate packaging, logos, and anti-

counterfeiting techniques such as holograms. It can also be unsophisticated, consisting of

inferior or hand-written labels, with disks folded into a plastic bag and sold on street corners. A recent trend in counterfeiting is the emergence of compilation CD-ROMs, where numerous

unauthorized software publishers’ programs appear on one CD-ROM. In any form, software

counterfeiting is very damaging to both the software developer and legitimate end users.

• Online. This form of piracy occurs when copyrighted software is downloaded to users

connected through a modem to an electronic bulletin board or the Internet without the

express permission of the copyright owner. This should not be confused with sharing public

domain software or providing “shareware.” Shareware is software that may or may not be

copyrighted but is generally offered for little or no charge by the author for nearly unrestricted use, including copying or sharing with others. Microsoft distributes promotional products, free

software, updates, or enhancements over bulletin boards or online services, which may or may

not be licensed for use solely with licensed Microsoft products. You should check the EULA

accompanying the product to determine how it can be used.

• License Misuse. This form of piracy occurs when copyrighted software is distributed outside the

restricted legitimate channels it was designed for or the product is used in ways not allowed in

the license agreement. Examples of license misuse include:



(1) Academic product misuse This form of license misuse occurs when a product that is manufactured, licensed, and

specifically marked for distribution to educational institutions and students at reduced

prices is diverted into normal commercial channels of distribution. Typically this

product will contain a sticker indicating that it is academic product and for use only

by educational institutions.

(2) Not for Resale (NFR) product misuse. Again, this form of license misuse occurs when a product that has been clearly

marked "Not for Resale," and is typically distributed as a promotional or sample

product and is not licensed for normal commercial distribution and use, is diverted into

normal commercial channels of distribution.

(3) Original equipment manufacturer (OEM) stand-alone product. This form of license

misuse occurs when OEM version software has been unbundled from its designated

computer system and distributed as a separate, “stand-alone” product. Microsoft’s

agreement with computer manufacturers prohibits them from distributing Microsoft

products in this fashion, i.e. without accompanying computer hardware.

Microsoft products on the retail shelf should never include a line on the front cover of the User’s Guide that states, “For Distribution Only With New Computer Hardware.”

(3) “Microsoft Easy Fulfillment” (MEF) product misuse. This form of license misuse occurs

when a “Microsoft Easy Fulfillment” (MEF) product is diverted into normal commercial channels of distribution. The MEF product may be distributed only to end users who

have a Select or Open (MOLP) license and who order the product in accordance with

their license terms. The MEF product has a sticker on the jewel case identifying the

product as “Microsoft Easy Fulfillment.”

(4) Volume licensing misuse. Volume Licensing enables organizations to acquire the rights

to copy and use specific Microsoft software products with agreements tailored to the

number of products needed at the particular organization. These volume programs

offer a broad range of products and licensing options and reduce administrative

overhead and software management costs.

Microsoft offers two types of volume license: a. Select provides savings for medium and large organizations with significant volume

requirements through forecasting software needs over a two-year period.

b. Open provides savings for small and medium organizations for licenses of as few as 20

units of a particular software product, with a simple ordering process.

Misuse under volume licensing occurs when organization copies software purchased

through the volume program on more computers than specified in their license

agreement. Other violations occur when an organization allows concurrent use of

software products (which currently is offered only as an option under the Select and Open

programs) without the purchase of the option that allows for this concurrent use.

User licenses show users rights to use pieces of software.

INTRODUCTION TO DATABASE SYSTEMS

A DATABASE is a shared and integrated collection of logically related records or files consolidated into a common pool that provides data for one or more uses.

� Is a collection of files?

� An organized collection of interrelated files.

� Is a collection of related files that provides a way of finding information quickly and easily

from a chosen reference point?

� Is an integrated collection of logically related records or files?

� A database consolidates records previously stored in separate files into a common pool of

data records that provides data for many applications.

� Examples of databases are MS Access, MS Works Database, and DBaseIV, Oracle, SQL



Building Blocks of a Database System

BIT � BYTE � FIELD � RECORD � FILE � DATABASE

• A byte is also known as a character

• A field is also known as a word

• A file is also called a table or relation

� File-Is a collection of related records. � Record-Is a collection of fields. It is a collection of fields arranged in a predefined

order. � Field-Is a collection of single items. It is an implementation of the data attribute. It

is the smallest unit of data to be stored in a database. � Primary key-Is a field whose value identifies one & only one record in a file. � Secondary key-An alternative index for identifying an entity. Its value can identify

single entity occurrences of all entity occurrences. A subset of all entity

occurrences. � Foreign key-Are pointers or links to occurrences of a different file. A foreign key in

one file must be a primary key in another file. � Descriptors-Are any other fields that describe business entities.

Traditional/Conventional/Flat Filing Systems

• This is programming with files. Each user defines and implements the files needed for a

specific application so that each application has its own separate data files and software

programs

• Although both users will be interested in the same data, each maintains separate files and

programs to manipulate these files and this results in data redundancy and a lot other

problems associated with it.

Advantages of the Database Approach • Control over data redundancy

• Increased data consistency/Reduced data confusion

• Increased data integrity – concerned with validity and accuracy of data

• Reduction in wastage of storage space

• Program/Data independence

• Increased productivity of application development

• Improved data security

• Data sharing

Disadvantages • Database systems are complex, difficult and time consuming to design

• There is greater impact of failure

• Extensive conversion costs involved

• Initial training is required for all users

• Concurrence problems - where more than one user access and attempt to update the

same record at the same time - there is file edit locking to prevent this.

• Ownership problems - sometimes some individuals tend to own the data and thus refuse

access by other individuals or departments in the organisation.

• Resources problem - with database extra resources are needed e.g. more workstations

and other devices. Substantial hardware and software startup costs are involved

Security problems - there is increased exposure to unauthorised entry into the data. However, this

could be reduced by the use of regularly changed passwords and by physically denying access to

unauthorised users.



DATABASE TERMINOLOGY

• Entity - a real world object or event or anything that is capable of independence existence and about which we can collect information e.g. person, building, transaction,

election

• Attribute – a characteristic or property of an entity e.g. name

• Primary key – an attribute that uniquely identifies an entity or record. A field that uniquely identifies a record in a table. In a students table, for instance, a key built from last name +

first name might not give you a unique identifier (two or more Jane Does in the school, for

example). To uniquely identify each student, you might add a special Student ID field to

be used as the primary key.

• Foreign key - A key used in one table to represent the value of a primary key in a related

table. While primary keys must contain unique values, foreign keys may have duplicates.

For instance, if we use student ID as the primary key in a Students table (each student has

a unique ID), we could use student ID as a foreign key in a Courses table: as each student

may do more than one course, the student ID field in the Courses table (often shortened to

Courses.student ID) will hold duplicate values.

• Normalization - The process of structuring data to minimise duplication and inconsistencies.

The process usually involves breaking down a single table into two or more tables and

defining relationships between those tables. The process of breaking up a table into multiple tables, each of which has a single theme, thereby reducing data redundancy; 2)

The technique that reduces or eliminates the possibility that a database is subject to

modification anomalies

• Query - A view of your data showing information from one or more tables. For example,

you could query a Students database asking "Show me the first and last names of the

students who take both history and geography and have Alice Hernandez as their

advisor". Such a query displays information from the Students table (firstname, lastname),

Courses table (course description) and Advisor table (advisor name), using the keys

(student ID, course ID, advisor ID) to find matching information. Literally, a question you ask

about data in the database in the form of a command, written in a query language,

defining sort order and selection, that is used to generate an ad hoc list of records; 2) The

output subset of data produced in response to a query.

• SQL - Structured Query Language (pronounced sequel or ess-queue-ell). A computer

language designed to organize and simplify the process of getting information out of a

database in a usable form, and also used to reorganize data within databases.

• Relation - A single store of related information. A table consists of records, and each

record is made up of a number of fields. You can think of the phone book as a table: It

contains a record for each telephone subscriber, and each subscriber’s details are

contained in three fields – name, address and telephone.

• DBMS - Database management system. A program which lets you manage information in

databases. Microsoft Access is a DBMS, although the term is often shortened to

‘database’. So, the same term is used to apply to the program you use to organize your

data and the actual data structure you create with that program. • Domain - A collection or range of all the possible values a field can contain. Although a

field’s domain is typically finite, it may be infinite as well.

• Derived attribute - Synonymous with computed attribute, for which the value is calculated

from those contained in other fields. Usually, computed fields’ values are calculated from

other fields’ values that occur in the same record

• Metadata - Data about data and the data’s structure within a database. Technical metadata reflects the description of the structure, content, keys, and indexes of data and

their source of origin, while business metadata reflects definitions about measures (facts)

using calculations

• OLAP - (Online Analytical Processing)The OLAP Council defines online analytical processing as, "A category of software technology that enables analysis, managers and executives to

gain insight into data through fast, consistent, interactive access to wide variety of possible

views of information that have been transformed from raw data to reflect the real

dimensionality of the enterprise as understood by the user."



• Record - Synonymous with row and tuple. An instance of data in a table, a record is a

collection of all the facts related to one physical or conceptual entity; often referring to a

single object or person, usually represented as a row of data in a table, and sometimes

referred to as a tuple in some, particularly older, database management systems.

• Schema - The database’s metadata -- the structure of an entire database, which specifies,

among other things, the tables, their fields, and their domains. In some database systems,

the linking or join fields are also specified as part of the schema

2) The description of a single table. Also called a Logical Schema.

• Concatenated key – a key formed by joining two or more attributes

• Relationship a link or association between any two entities in a database

• ERD - An entity-relationship (ER) diagram is a specialized graphic that illustrates the

interrelationships between entities in a database. ER diagrams often use symbols to

represent three different types of information. Boxes are commonly used to represent

entities. Diamonds are normally used to represent relationships and ovals are used to

represent attributes. TYPES OF DATABASE RELATIONSHIPS One-to-One

o Exactly one record in one table is related by a common linking field to exactly one record

in another table, implying that each value of the linking field appears no more than once in each of the tables. Both tables can have only one record on either side of the

relationship. Each primary key value relates to only one (or no) record in the related table.

They're like spouses—you may or may not be married, but if you are, both you and your

spouse have only one spouse. Most one-to-one relationships are forced by business rules

and don't flow naturally from the data. In the absence of such a rule, you can usually

combine both tables into one table without breaking any normalization rules.

One-to-Many

o Exactly one record in one table is related by a common linking field to one or more

records in another table, implying that each value of the linking field is unique in the first

table, but not necessarily so in the second. The primary key table contains only one record

that relates to none, one, or many records in the related table. This relationship is similar to

the one between you and a parent. You have only one mother, but your mother may

have several children.

Many-to-Many

• One or more records in one table may be related to one or more records in a second table by a common value or linking (join) field. This implies that each value of the linking

field may appear any number of times in either or both tables. Each record in both tables

can relate to any number of records (or no records) in the other table. For instance, if you

have several siblings, so do your siblings (have many siblings). Many-to-many relationships

require a third table, known as an associate or linking table, because relational systems

can't directly accommodate the relationship.

The Database Administrator This is a person responsible for planning, designing and maintaining the organisation's database.

This person relates to the management, system analysts, programmers and other stakeholders in

the organisation. He needs to have adequate managerial and technical abilities to suit the job. He

therefore must have a sound knowledge of the structure of the database and the DBMS.

Responsibilities of the Database Administrator (DBA)

• Ensures that the database meets the needs of the organisation.

• Ensures facilities for the recovery of data

• Ensures the functioning of report generation systems form the DBMS

• The DBA is also responsible for the documentation of the DBMS through the designing and

availing of the data dictionary and manuals for the users giving such direction as the



general use of the database, access to information, deletion of records from the system

and the general validation and verification of data.

• The design of the database

• After the initial design, the DBA must monitor the performance of the database, and if

problems surface (such as a particular report taking an unacceptably long time to

produce), appropriate changes must be made to the database structure.

• Keeping users informed of changes in the database structure that will affect them; for

example, if the size or format of a particular field is altered or additional fields added

• Maintenance of the data dictionary for the database, and responsibility for establishing

conventions for naming tables, columns, indexes & so on.

• Implementing access privileges for all users of the database; that is, specifying which items

can be accessed and / or changed by each user.

• Allocating passwords to each user.

• Providing training to users in how to access and use the database.

• Manage the organizations

• -data resources

• -database plans

• -design

• -operations

• -training • -user support

• -security & Maintenance

• Maintain data consistency and security

• Approve access to data stored

• Approve access procedures

• ABILITY to delete, add, modify –existing data must be tightly controlled.

Database Management System (DBMS) The DBMS is an application program that provides an interface between the operating system and

the user in order to make access to the data as simple as possible. It has several other functions as well, and these are described below.

1. Data storage, retrieval and update. The DBMS must allow users to store retrieve and update

information as easily as possible, without having to be aware of the internal structure of the

database.

2. Creation and maintenance of the data dictionary 3. Managing the facilities for sharing the database. The DBMS has to ensure that problems do

not arise when two people simultaneously access a record and try to update it

4. Back up and recovery. The DBMS must provide the ability to recover the database in the

event of system failure.

5. Security. The DBMS must handle password allocation and checking, and the ‘view’ of the

database that a given user is allowed. The data dictionary The data dictionary is a ‘database about the database’. A data dictionary, as defined in the IBM Dictionary of Computing, is a "centralized repository of information about data such as meaning,

relationships to other data, origin, usage, and format."[1] The term may have one of several closely

related meanings pertaining to databases and database management systems (DBMS):

• a document describing a database or collection of databases

• an integral component of a DBMS that is required to determine its structure

• a piece of middleware that extends or supplants the native data dictionary of a DBMS It will contain information such as:

1. What tables and columns are included in the present structure?

2. The names of the current tables and columns

3. The characteristics of each item of data, such as its length and data type;

4. Any restrictions on the value of certain columns



5. The meaning of any data fields that are not self-evident; for example, a field such as

‘course type’;

6. The relationships between items of data

7. Which programs access which items of data, and whether they merely read the data or

change it?

Advantages and any disadvantages of databases # ADVANTAGES # DISADVANTAGES 1 Supports data sharing 1 Limitations of databases arise from increased

technological complexity

2 Ensures increased data security 2 Developing a large database and installing a

DBMS can be difficult and expensive.

3 Ensures data independence 3 More hardware capability is required, since

storage requirements for the organization of data, overhead control data, and the DBMS is

greater

4 Data integrity is guaranteed. The functions in the DBMS can be used to enforce the integrity rules with minimum programming in the

application programs.

4 Problems of data inconsistency can arise if a

distributed database approach is used.

5 Reduces or minimizes data redundancy 5 Longer processing times may result from high

volume transaction processing applications since extra layer software [the DBMS] exists

between application programs and the

Operating system.

6 Consistence of data is ensured

6 Security and integrity of data are major concerns.

7 Support data integration. Since related data is stored in one single database, enforcing data

integrity is much easier

Centralized databases are vulnerable to errors,

fraud and failures.

8 Related data can be shared across programs since the data is stored in a centralized manner

9 Enforcing of standards in the organization and structure of data files is required and also easy

in a Database System, since it is one single set

of programs, which is always interacting with data files

10 The application programmer need not build the

functions for handling issues like concurrent

access, security, data integrity, etc. The programmer only needs to implement the

application business rules. This brings in

application development ease.

Q* Limitations of file Processing Systems that the DBM system address i. Data duplication - Same kind of information is stored in several files

ii. Lack of Data integration – Independent files make it difficult to provide end users with info

for ad-hoc requests that require accessing data stored in different files

iii. Data dependence – In a file processing system, the organization of files, their physical

location on storage hardware and application software used to access those files depend

on each other. Changes in format and structure o data and records in file require changes to all the

programs

Q* what is a DBMS (Data base Management System) Is a collection of software programs that:

i. Stores data , in a uniform and consistent way

ii. Organizes the data, into records in a uniform and consistent way

iii. Allows access to the data, in a uniform and consistent way



A collection of software programs that stores organizes and allows access to the

data in a uniform and consistent way

Is a collection of programs that enables users to create and maintain a

database?

A general purpose software system that facilitates the process of defining

constructing and manipulating databases for various applications.

Database Environment i. Database

ii. Database users

iii. DBM System

iv. Data Dictionary

v. Database Administrator

vi. User/system interface

Database Users i. Casual users

ii. Naïve users – parametric users

iii. Sophisticated end users

I. Occasionally use it, and if they do a HLL such as AQL may be used.

II. Those who use Standard queries and updates only e.g. bank cashiers, data entry

clerks’ e.t.c.

III. Know the whole range of facilities on a database environment.

Q a. Explain the 3 Major disadvantages of a file system (6) b. Give and explain any 7 functions of a DBMSystem FUNCTIONS OF A Database Management SYSTEM

1. Storage, Retrieval &Update

2. Catalogue

3. Logical transactions

4. Concurrency control

5. Recovery

6. Security

7. Communications

8. Integrity

9. Data Independence

10. Utilities

1. Storage, Retrieval &Update - Allows users with the ability to store, retrieve and update data in the database.

2. Catalogue - Allows a catalogue in which descriptions of data items are stored and which is

accessible to users

3. Logical Transactions - Allows a mechanism which will ensure that either all of the updates corresponding

to a given transaction are made or not made. .e.g.

ABORT – ROLLBACK or undo all the changes

COMMIT- Transaction gone thru and is already in the database.

4. Concurrency Control - Allows a mechanism to ensure that the database is updated correctly when

multiple users are updating the database concurrently

LOCKING OR DEADLOCK situations must be avoided

5. Recovery - Allows a mechanism for recovering the database in the event that the database

is damaged in any way.



- A before / after image is usually created

6. Security - Allows a mechanism to ensure that only authorized users can access the

database.

- Authorizations, encryption features and limited views can be used as security

provisions

7. Communication - Must be capable of integrating with communications software on the database

environment on a multi-user environment.

8. Integrity - Allows a mechanism to ensure that both the data in the database and changes

to the data follow certain rules.

9. Data Independence - (Has facilities to) support the independence of programs from the actual structure

of the database.

10. Utilities - Provide a set of utility services e.g. optimized

COMPONENTS OF A DBMS 1. Data dictionary/directory 2. Data language

3. Application development tools

4. Security software

5. Report writers

6. Query language

7. Web server software

8. Teleprocessing monitors

9. Archiving, backup and Recovery systems

1. DATA DICTIONARY/ DIRECTORY

• Contains the names and descriptions of every data element in the

database.

• Also contains descriptions of how data elements relate to one another.

• Ensures that data is stored in a uniform and consistent manner hence

reducing redundancy.

2. DATA LANGUAGES

• Data description language (DDL) describes the characteristics of data elements.

• DDL requires the application program to use standardized commands to retrieve and

process data from a database.

• Data manipulation language (DML) consists of commands such as FIND, GET, INSERT

3. APPLICATION DEVELOPMENT TOOLS • A program designed to help programmers develop application programs that use the

database e.g. CASE TOOLS

4. SECURITY SOFTWARE • Provides a variety of tools to shield database from unauthorized access and from viruses

5. REPORT WRITERS • Allows programmers, mgrs and others to design out put reports.

6. QUERY LANGUAGE • A set of commands used primarily for accessing data from a database.

• You can ask ad-hoc questions of the database interactively without the aid of

programmers.

• Examples SQL, NLQ, QBE. Structured Query language, Natural language Queries and

Query by Example.

7. WEB SERVER SOFTWARE • Turns the computer system housing database into a web server and enables users with

web connection to access data from wherever they are located.

• Also convert data into a format that is readable by standard browsers.



8. TELEPROCCESSING MONITORS • A software package that manages communication between the database and remote

terminals.

9. ARCHIVING, BACK UP AND RECOVERY SYSTEMS • Provides the database manager with tools to make copies of the database.

• Restart/ Recovery systems are tools used to restart the database and to recover lost data

in the event of a failure.

OBJECTIVES AND BENEFITS OF DATABASE APPROACH

1. Data redundancy is reduced –reduces the duplication of data.

2. Data inconsistence avoided.

3. Sharing of data is promoted –since data is stored in centralized.

4. Standards are enforced, thru the data dictionary /catalogue

5. Base of application development /maintenance is available

6. Uniform security/ privacy /integrity control s are applicable to group of users

7. SECURITY – Passwords, access controls

PRIVACY - Authorized users

INTEGRITY – Accurate data

8. Integration of data is achieved - since data is stored in one db 9. Data independence is achieved/ observed - it is the immunity of applications to changes in

storage structure and access strategy.

10. Data accessibility and responsiveness.

11. Structured Query Language e.g. select name from customer where town = Harare”

RISK TO DATABASE APPROACH 1. New, specialized personal

2. Backup – important DBMS function (Recovery)

3. Shared data – conflict and concurrency control

4. Technological complexity

5. Expensive to develop a large database and installing a DBMS can be difficult.

6. More hardware capability is required – storage requirements overhead control data and

the DBMS required more memory

7. Problems of inconsistence can arise if a distributed data approach is used.

8. Longer processing time may result from high volume transaction processing applications.

9. Security and integrity are major concerns.

10. Centralized database are vulnerable to errors fraud and failures.

DATABASE MODELS OR TYPES OF DATABASES i) Hierarchical database model

ii) Network database model

iii) Relational database model

iv) Object-oriented database model

Hierarchical Database Model • It resembles an inverted tree structure, organogram or family tree. It reflects one-to-one

(1:1) or one-to-many (1:M) relationships only among the records.

• The uppermost record is called the root and from there data are organized into groups

containing parent and child records(nodes)

• A parent record is allowed to have one or more child records but a child node can have

only one parent

• Because relationships between data items follow clearly defined paths, access to data is

fast

• There is no relationship between brother or sister nodes

• Each record is related to others in a parent-child relationship or tree structure.



• Relationships between among records form a hierarchy or tree structure.

• The relationship among records is one to many since each data element is related only to

one element above it.

• Searching a record involves moving progressively downward from a root and along the

branches of the tree until the desired record is located.

Diagram

Network Database Model

• Is almost similar to the hierarchical model but is more flexible and versatile because a

record can be linked to any other record in the model; i.e. the network model can reflect

a many-to-many (M:N) relationship.

• The route to data is not necessarily downwards but can in any direction

• The major advantage is its ability to handle sophisticated relationships among various

records and more than one path can lead to desired data level

• Network complexity limits users in their ability to access the database without the help of

programming staff

• A record can belong to a number of parents

• Relationship among records is many to many

• Allows entry into a database at multiple points because any data element or record can

be related to many other data elements.

• Permits a record to be a member of more than one set at a time Hierarchical and network models are less flexible than other database models because the relationship between

records must be determined and implemented before a search can be conducted.

Diagram

DEPT

Student

Course



Relational Database Model • Data elements are viewed as being stored in the form of tables(relations)

• There are no pointers or links to talk about but the data is organized into two dimensional

tables which are known as relations

• Each table is composed of unique rows or records which are also known as tuples and

each cell in the relation must be single valued

• Relationships are either 1:1 or 1:M and in the case where M:N relationships exist junction

tables are created All data elements within the database are viewed as being stored in

the form of tables

• Database Packages based on this structure link records in different or various tables to

provide information to users as long as the share common data elements.

• Data is organized in 2-dimensional tables.

Diagram

CUSTOMER

CUSTOMER NO. CUSTOMER NAME CUSTOMER ADDRESS

- - -

- - -

Object Oriented Model • Each object is bound together with its own data and a set of instructions that describe the

behaviour and attributes of the object

• The objects use messages to interact with one another e.g. the object building in a

database can have the attributes: type, size, colour etc

• This model uses objects and messages to accommodate new types of data and provide

for advanced data handling

� Each object in an object-oriented database model is bound together with its own data

and a set of instructions that describe the behavior and attributes of the objects.

� Objects use messages to interact with one another.

� Every object is described by a set of attributes.

� E.g. the object building in a database or architectural drawing may have the attributes

TYPE, SIZE, COLOUR just as in any. � Every object must have a set of procedures or routines or a set of methods.

� E.G methods for an architectural drawing might include instructions to display, rotate, or

explode the drawing on a screen.

FILE CONCEPTS

The purpose of a computer file is to hold data required for providing information. A computer file is

a collection of related records. Records consist of fields and the fields are made up of characters.

A character is the smallest element of a file. A character may be a letter of the alphabet, a digit or

of a special form (symbols). Logical files show what data items are contained and what processing

may be done while physical files are viewed in terms of how data is stored on storage media.

Types of Files

a) Master Files They hold permanent data for use in applications such as stock control and credit

control. Usually much of the data items in these files do not change frequently or with

each transaction, e.g. name, address or date of birth.

b) Transaction files



These are also called movement files. They hold temporary records of values. They are

used to update the master file and are overwritten after the updating of the master file.

Examples of Transaction files:

• A customer order file or records, each of which has data on a particular order.

• A time sheet data file that contains records, each of which has data on the

number of hours worked by a particular employee.

• A stock transaction file that contains records of stock additions or removals –

one record for each movement.

c) Look up files They are reference files from which such information as prices list and mailing list can be

obtained.

d) Archive files These are files that are used to store information that has not been in use in the recent

past and would not be in use in the near future – so are used to store historical data. e) Backup files These are copies of transaction files and master files held for security purposes

f) Transition files Derived from a transaction file by the addition or deletion or ammendment of data. It is

produced as a temporary file during data processing often by the addition of master

file information to a transaction file prior to updating or output. Examples of transition

files:

• An employee time sheet transaction file which has had employee names

added (from an employee master file) and re-sorted into department order

• A customer order transaction file to which the price of each item ordered has

been taken from a (computerised) catalogue and added

FILE PROCESSING

� Is the process of updating the records in a file to accurately reflect changes in the

data?

� It can be a manual process where procedures are in place to update forms,

which are sent to the respective person responsible for the update.

� It can also be a computerized process where information is first stored in

transaction files until the master file is updated.

File processing methods: 1. BATCH PROCESSING is execution of a series of programs ("jobs") on a computer without manual

intervention.

� Batch jobs are set up so they can be run to completion without manual intervention, so all input data is preselected through scripts or command-line

parameters. This is in contrast to "online" or interactive programs which prompt the

user for such input. A program takes a set of data files as input, process the data,

and produces a set of output data files. This operating environment is termed as

"batch processing" because the input data are collected into batches on files

and are processed in batches by the program. Batch Processing � Transactions are collected and processed in batches [groups].

� Transaction processing in which transactions are gathered and stored for

later execution.

� E.g. a supermarket chain operates 5 outlets. At the end of the day all

information on sales [transaction file] is collected, & the main records

[master file] are updated with the sales for that day.

� Performs a group of tasks all at once, while requiring little [or no]

interaction with the user.



� It is a great time saver because the computer can perform repetitive

functions quickly & consistently.

Benefits Batch processing has these benefits:

• It allows sharing of computer resources among many users and programs,

• It shifts the time of job processing to when the computing resources are less busy,

• It avoids idling the computing resources with minute-by-minute mannual intervention and supervision,

• By keeping high overall rate of utilization, it better amortizes the cost of a computer, especially an expensive one.

COMMON BATCH PROCESSING USAGE

• Data processing • A typical batch processing procedure is End of day-reporting (EOD), especially on

mainframes. Historically systems were designed to have a batch window where online

subsystems were turned off and system capacity was used to run jobs common to all data

(accounts, users or customers) on a system. In a bank, for example, EOD jobs include

interest calculation, generation of reports and data sets to other systems, print (statements)

and payement processing.

• Printing • A popular computerized batch processing procedure is printing. This normally involves the

operator selecting the documents they need printed and indicating to the batch printing

software when, where they should be output and priority of the print job. Then the job is

sent to the print queue from where printing daemon sends them to the printer.

• Databases • Batch processing is also used for efficient bulk database updates and automated

transaction processing, as contrasted to interactive online transaction processing (OLTP)

applications. • Images • Batch processing is often used to perform various operations with digital images. There exist

computer programs like Batch Image Processor that let one resize, convert, watermark, or

otherwise edit image files.

• Converting • Batch processing is also used for converting a number of computer files from one format to

another. This is to make files portable and versatile especially for proprietary and legacy

files where viewers are not easy to come by.

• Job scheduling • UNIX utilizes cron and at facilities to allow for scheduling of complex job scripts. Windows

has a job scheduler. Most high-performance computingclusters use batch processing to

maximize cluster usage.

2. REAL-TIME PROCESSING,

A real-time operating system (RTOS) OR REAL-TIME PROCESSING is a multitaskingoperating system

intended for real-time applications. Such applications include embedded systems (programmable

thermostats, household appliance controllers), industrial robots, spacecraft, industrial control (see

SCADA), and scientific research equipment.

A RTOS facilitates the creation of a real-time system, but does not guarantee the final result will be

real-time; this requires correct development of the software. An RTOS does not necessarily have

high throughput; rather, an RTOS provides facilities which, if used properly, guarantee deadlines

can be met generally or deterministically (known as soft or hard real-time, respectively). An RTOS will typically use specialized scheduling algorithms in order to provide the real-time developer with

the tools necessary to produce deterministic behavior in the final system. An RTOS is valued more

for how quickly and/or predictably it can respond to a particular event than for the amount of

work it can perform over a given period of time. Key factors in an RTOS are therefore a minimal

interrupt latency and a minimal thread switching latency.



� An early example of a large-scale real-time operating system was Transaction

Processing Facility developed by American Airlines and IBM for the Sabre Airline

Reservations System. � Real-time Processing

� The master records are updated as and when the transactions occur.

� A form of transaction processing in which each transaction is executed as

soon as complete data becomes available for the transaction.

� A supermarket chain would be linked by a network to a main computer.

� Each time a sale is made the stock information is updated and the sale

information is also updated.

� It is expensive and complicated.

� Record and file locks are implemented to avoid problems with real-time

processing.

3. ONLINE PROCESSING, or OLP, refers to a class of systems that facilitate and manage transaction-

oriented applications, typically for data entry and retrieval transaction processing. The term is

somewhat ambiguous; some understand a "transaction" in the context of computer or database

transactions, while others (such as the Transaction Processing Performance Council) define it in

terms of business or commercial transactions. OLP has also been used to refer to processing in which the system responds immediately to user requests. An automatic teller machine (ATM) for a

bank is an example of a commercial transaction processing application.

� The technology is used in a number of industries, including banking, airlines,

mailorder, supermarkets, and manufacturing. Applications include electronic

banking, order processing, employee time clock systems, e-commerce, and

eTrading. The most widely used OLP system is probably IBM'sCICS. � Online processing

� A general term for when one computer is interacting directly and

simultaneously with another computer. Many sources of information are

available online.

� Available for immediate use.

� The master file is updated with the transactions through some form of

communication link.

� All real-time processing involves online processing.

� Not all online processing needs to be real-time.

� Require interaction of the user.

Benefits Online Processing has two key benefits: simplicity and efficiency. Reduced paper trails and the

faster, more accurate forecasts for revenues and expenses are both examples of how OLP makes

things simpler for businesses.

Disadvantages As with any information processing system, security and reliability are considerations. Online transaction systems are generally more susceptible to direct attack and abuse than their offline

counterparts. When organizations choose to rely on OLP, operations can be severely impacted if

the transaction system or database is unavailable due to data corruption, systems failure, or

network availability issues. Additionally, like many modern online information technology solutions,

some systems require offline maintenance which further affects the cost-benefit analysis.

� Centralized processing

� An information system where all critical data and programs are stored on

one main computer, usually a mainframe. Unlike the task-sharing concept

of a client/server system, the central computer retains all the brains and

brawn. � A computing environment in which all processing takes place on a

mainframe or central computer. � Puts all processing and control authority within one computer to which all

other computing devices respond.



� Distributed Processing � The ability to have several computers working together in a network,

where each processor runs different activities for a user, as required. � Computers connected together by a communications network. Data

processing occurs on each of the computers, unlike a centralized

processing system in which terminals are connected to a host computer

that performs all of the data processing. � Use of computers at various locations, typically interconnected via

communication links for the purpose of data access and/or transfer. � A computer system in which processing is performed by several separate

computers linked by a communications network. The term often refers to

any computer system supported by a network, but more properly refers to

a system in which each computer is chosen to handle a specific

workload, and the network supports the system as a whole. � Offline processing

� When your computer performs an operation when it is not connected to

any other computers, it is working offline.

� Means that your computer is not currently connected to an Internet

server.

� Not connected (to a network). Not available to the network � Time sharing

� A way of sharing out computer facilities between a number of people

who want to use the computer at the same time. Each has a separate

terminal and gets the impression that they have sole use of the computer

with their own 'account'. Similar to NETWORKING.

� Transaction processing o A type of computer processing in which the computer responds immediately

to User requests, with each User interaction considered to be a transaction.

Automatic teller machines for banks are probably the best-known example.

o In computer science, transaction processing is information processing that is

divided into individual, indivisible operations, called transactions. Each

transaction must succeed or fail as a complete unit; it cannot remain in an

intermediate state.

Master file is the main information source in any type of

organization. File processing is the update of the master file [actual records]

through manual or computerized methods.



FILE ORGANIZATION METHODS & ACCESS � File Organization-Is the arrangement of data records on storage media

� It determines the manner in which individual records can be accessed or

retrieved

Definitions of cycle time on the Web:

• The time usually expressed in seconds for a controller to complete one on/off cycle.

Definitions of access time on the Web:

• The average time interval between a storage peripheral (usually a disk drive or

semiconductor memory) receiving a request to read or write a certain location and

returning the value read or completing the write. The amount of time it takes a computer to locate an area of memory for data storage or

retrieval.

• The time required to retrieve data from a storage device and transmit it to a specified

location.

Definitions of random access on the Web:

• Storage systems where data may be stored and accessed in any order, independent of the ordinal position of the data when it was originally recorded. This is the opposite of linear

(3) access, or linear recording media such as magnetic tape, which necessarily preserves

the sequential relation of the data as it is recorded, and depends on this sequential

relation for accurate playback. See non-linear recording.

• Able to read any location directly; without having to read sequentially to the location. Definitions of sequential access on the Web:

• Data must be read in the order it appears. This method applies to tape, and to a lesser degree to disks.

Reading data from a file whose records are organized on the basis of their successive

physical positions. To reach a specific record, all records previous to that record must be

read, in order. Magnetic computer tapes are sequential access storage device.

• Refers to reading or writing data records in sequential order, that is, one record after the other. To read record 10, for example, you would first need to read records 1 through 9.

This differs from random access, in which you can read and write records in any order.

TYPES OF QUERIES

i. DIRECT QUERY

ii. INVERTED QUERY

i. DIRECT QUERY • Is one where the user can identify the entity in which he is interested?

• He may want to know some of the particular of attributes of that entity.

• e.g. Where a sales man wants to know the amount and location of a particular product in

the organization.

• He is able to identify the product by name or product number and this identification is

used as the key for making the query which is also the primary record key. • The basic purpose of the direct query is to know the attribute values of already identified

entities

ii. INVERTED ENTITIES



• is one where the user does not know the identification of entities in which he is interested

• he wants to identify the entities by some criteria or attribute values

• e.g. the purchase department requiring a list of items for wh9ch the stock level is below the

desired level

• in this case user does not know the identity of items already but want to know it

• only specify a criterion as the basis of the query

• Obviously the primary key cannot be used for retrieval, it is not available

• Some attribute like stock level has to be used for the retrieval of records

MODELS OF FILE ORGANISATION

i. serial file organization

ii. sequential file organization

iii. indexed sequential file organization

iv. direct file organization

v. inverted file organization

i. SERIAL FILE ORGANISATION • Is one where records are not stored in any particular order • They are stored in the order in which they are received

• New records are added at the end of the files

• This method of file organization is used when

- the usage of the records is not clearly known

- as a means of recording transaction as they happen

- as dump files reflecting the physical layout of a file

- as a prelude to organizing the file in another order i.e. transactions may be

punched and stored on a serial file, the file may be subsequently be stored into a

desired sequence

- gives maximum utilization of space

- no room is left for inserting other records

- does not cater for direct access to records

- used on magnetic tapes

- popular on output files, archive files, security files

i. SEQUENTIAL FILE ORGANISATION - records are arranged in a pre-determined sequence determined by the primary

key

- appropriate for files which are store on tape or disk

- nor generally used for online system that demand fast response

- mainly used for batch processing applications

- suitable when there is for little file enquiry

- can be used for variable length records as well as fixed length records - waste space as some space is left of reserved for other records to be inserted in

order to preserve the order or organization

� UPDATING � Updating on tape is carried out in batch mode by reading the whole file and

rewriting it after necessary modification on to a new file.

� On disk can be carried out without rewriting the whole file.

� RETRIEVAL � Retrieval of a record from a sequential file on tape media can be made only in

the sequential mode by reading all the records in sequence till the desired record

is reached.

� Retrieval of a record from a sequential file on direct access media (DISK) can be

made by using sequential reach skip search, binary search.

� HIT RATE



� In a batch processing run: The proportion of the number of records processed

during a run to the total number of records on the file is called a hit rate.

� The higher the volatility and the lower the frequency of updating,, the higher the

hit rate.

� PROCESSING OF SEQUENTIAL FILES � Tapes provides for only serial access

� Disks can be accessed in a serial order or random order.

iii) INDEXED SEQUENTIAL FILES

• Records are stored in sequence but in addition an index is provided to enable individual

records to be located directly after reading the index.

• Records are pointed to by indexes.

• Used with disks only not with magnetic tapes.

• Wastes space.

• The index may be ignored and the data is read sequentially

• The file may be accessed sequentially but using the index to skip over unwanted records

=selective sequential access

• Index may be read into memory and used to obtain data randomly.

• Records can be accessed sequentially OR randomly.

iv) DIRECT FILE ORGANISATION Files are stored or haphazardly and an address key is used as reference.

Records are physically located at an address that is calculated from its primary

key field.

The calculation of the address from the key field is called hashing.

Records are scattered on the storage disk instead of being arranged next to one

another or linked via a pointer field.

Records can rapidly be retrieved and accessed directly

Used on magnetic disks (e.g. floppies, hard disk) and optical disks.

Costly in terms of device used and space.

v) INVERTED FILE ORGANISATION special case of indexed sequential organization

an index is maintained for every attribute in the record

the main file itself may not be stored if direct queries are not to be handled

the entire file data is, in any case, stored in the indexes

Useful for handling inverted queries.

vi) MULTI-RING FILE ORGANISATION useful for handling inverted query when sets of records have same attribute value

Each set of records with same attribute values is linked into a ring.

A ring of records is a chain where the last in the chain points to the first. One of the records is anchored to the index so that it provides an entry point into

the ring.

The index of the attribute is read first to retrieve records with a particular attribute

value.

All records with that attribute value can be located.

COMPUTER MEMORY

RAM (Random Access Memory) Also referred to as Main Memory, Primary Memory or Working Memory is memory that is

accessed by the CPU as it processes information. The CPU also places results of processing

on the memory chip. The memory has the following characteristics.

1) can be read from

2) can be changed and can be rewritten

3) used for short-term storage of data i.e. it is temporary storage,



4) is volatile (data lost when power is turned off).

Types of RAM

• DRAM (Dynamic RAM) This is the most common type of computer memory. DRAM needs

refreshing and is refreshed hundreds of times each second in order to retain data. During

recharging it cannot be accessed by the CPS

• SRAM (Static RAM) SRAM is approximately 5 times faster (and twice as expensive, as DRAM). It does not have to be constantly refreshed. Because of its lower cost and smaller

size, DRAM is preferred for the main memory, while SRAM is used primarily for cache

memory.

• SDRAM (synchronous dynamic RAM) is the standard memory offering in the PC industry and is faster than DRAM because it's synchronized to the system clock. . It is designed for

mainstream home and business applications, email, and basic audio and video streaming.

It provides single-channel memory and is available on our mainstream and value desktop

system.

• DDR SDRAM (double data rate synchronous dynamic RAM) takes all the features of ordinary SDRAM and increases the frequency bandwidth to improve system performance

and speed.

• RDRAM (Rambus dynamic RAM) is able to load a new stream of data before the previous stream has completed, resulting in faster access speeds. The RDRAM memory features

dual-channel processing which doubles data throughput to further enhance

performance. This type of memory is optimized for high-end multimedia tasks involving

video and audio. Dual Channel RDRAM is shipped on our performance desktop systems

powered by Pentium 4 processors

• VRAM: Memory designed for storing the image to be displayed.

• CACHE RAM is a small block of high-speed memory located between the Processor and

main memory and is used to store frequently requested data and instructions. When the

processor requests data, it will check in the cache first

The computer has two types of memory chips within the system unit, known as RAM and ROM.

ROM (Read Only Memory)

This memory chip has essential programs that start up the computer hardwired on the

microchip during the manufacture of the computer. It forms what is known as FIRMWARE,

being a halfway between hardware and software. The characteristics of this memory are

that:-

1) can be read from,

2) cannot be changed

3) is permanent

4) non-volatile (data not lost when power is turned off).

� ROM � Stores instructions & data which do not change

� It is written once during manufacture

� It is for holding software such as MS-DOS.Windows 95, 98.XP.

� It is programmed by the manufacturer and cannot be altered by the user

� It is static & non volatile

� It stores control routines for personal computers

VARIATIONS OF ROM Allow users to store and in some cases to change data stored in ROM

� PROM [Programmable ROM] is not programmed during manufacture but can be

programmed by the user. It is programmed according to the needs of the user

organization. If you make a mistake the ROM once programmed will became

permanent to the effect that any errors will never be corrected thus the user will

throw away any chip if errors are made.



� EPROM [Erasable Programmable ROM] can be programmed and erased as many

times. This time you don’t have to worry about errors too much because there is

room for correction. The programming is done electronically. Stored data can be

lost by exposing it to Ultra Violet light over a period of minutes.

1) EEPROM [Electrically Erasable Programmable ROM] can be read, erased, rewritten, without removing from the computer. The erasing & rewriting process is

very slow compared with reading, which limits their use. These can be erased &

programmed with electrical pulses. Can be erased in a few Milliseconds

MEMORY CAPACITY Everything entering into the computer is converted into digital (number) form, and is stored

in that form. When one needs to view the information, it is converted into human sensible

text, graphics, audio or video by the operating system. A binary digit is known as a bit being either a ‘0’(zero) or a ‘1’(one). It is the smallest item that can be stored in a

computer’s memory.

Memory capacity is measured in bytes, a byte being a set of eight(8) bits and the byte often represents a single character. Measurement units used for computer memory are:-

o BIT 1 binary digit (Either a 0 or a 1) o BYTE Eight bits. o NIBBLE Half byte/4 bits o KILOBYTE (KB) 1024 bytes o MEGABYTE (MB) Million bytes o GIGABYTE (GB) Billion bytes o TERABYTE Trillion bytes

NETWORKS

� A computer network, often simply referred to as a network, is a collection of computers

and other hardware components interconnected by communication channels that allow

sharing of resources and information Where at least one process in one device is able to

send/receive data to/from at least one process residing in a remote device, then the two

devices are said to be in a network. Simply, more than one computer interconnected

through a communication medium for information interchange is called a computer

network.

� Networks may be classified according to a wide variety of characteristics, such as the

medium used to transport the data, communications protocol used, scale, topology, and

organizational scope.

� Communications protocols define the rules and data formats for exchanging information

in a computer network, and provide the basis for network programming. Well-known

communications protocols include Ethernet, a hardware and link layer standard that is ubiquitous in local area networks, and the Internet protocol suite, which defines a set of

protocols for internetworking, i.e. for data communication between multiple networks, as

well as host-to-host data transfer, and application-specific data transmission formats.

� Computer networking is sometimes considered a sub-discipline of electrical engineering,

telecommunications, computer science, information technology or computer

engineering, since it relies upon the theoretical and practical application of these

disciplines.

Properties Computer networks:

1. Facilitate communications Using a network, people can communicate efficiently and easily via email, instant

messaging, chat rooms, telephone, video telephone calls, and video conferencing.

2. Permit sharing of files, data, and other types of information



In a network environment, authorized users may access data and information stored on

other computers on the network. The capability of providing access to data and

information on shared storage devices is an important feature of many networks.

3. Share network and computing resources In a networked environment, each computer on a network may access and use resources

provided by devices on the network, such as printing a document on a shared network

printer. Distributed computing uses computing resources across a network to accomplish

tasks.

4. May be insecure A computer network may be used by computer hackers to deploy computer viruses or

computer worms on devices connected to the network, or to prevent these devices from

normally accessing the network (denial of service).

5. May interfere with other technologies Power line communication strongly disturbs certain forms of radio communication, e.g.,

amateur radio. It may also interfere with last mile access technologies such as ADSL and

VDSL.

6. May be difficult to set up A complex computer network may be difficult to set up. It may also be very costly to set

up an effective computer network in a large organization or company.

NETWORK TOPOLOGIES

A network topology is the arrangement of elements (such as data links or nodes) in a network. It is

the physical arrangement of terminals in a local area network. The choice of topology is

dependent upon

• type and number of equipment being used

• planned applications and rate of data transfers

• required response times

• cost

Definitions of hub on the Web:

� A common connection point for devices in a network. Hubs are commonly used to

connect segments of a LAN. A hub contains multiple ports. When a packet arrives at one

port, it is copied to the other ports so that all segments of the LAN can see all packets. A

passive hub serves simply as a conduit for the data, enabling it to go from one device (or

segment) to another. ... � Node – a terminal point in a communications network.

� Workstation – A computer terminal or micro- or minicomputer system designed to support the work of one person.

MESH TOPOLOGY

Mesh topology work on the concept of routes. In Mesh topology, message sent to the destination

can take any possible shortest, easiest route to reach its destination. In the previous topologies star

and bus, messages are usually broadcasted to every computer, especially in bus topology.

Similarly in the Ring topology message can travel in only one direction i.e clockwise or

anticlockwise. Internet employs the Mesh topology and the message finds its route for its

destination. Router works in find the routes for the messages and in reaching them to their

destinations. The topology in which every devices connects to every other device is called a full

Mesh topology unlike in the partial mesh in which every device is indirectly connected to the other

devices.



STAR TOPOLOGY

� Is a network in which nodes are connected to a central component as its hub? � The central component can be a switching device like a switch or PABX [private

automatic branch exchange], a computer [minicomputer to which workstations

or PCs are connected] or just a wiring center that is a common termination point

for the nodes, called a hub.

� A HUB is a component that serves as a common termination point for multiple

nodes and that can relay [store & forward] signals along the appropriate paths. Definitions of star network on the Web:

• A network in which all terminals are connected through a single point, such as a star coupler.

• A network topology in the form of a star. At the center of the star is a wiring hub or

concentrator, and the nodes or workstations are arranged around the central point

representing the points of the star.

Advantages of star topology � It is easy to add or remove nodes

� Because each node has its own link to the central node, the star is more reliable than

other topologies.

� Full utilization of resources i.e. printer, sharing of processor

� Direct connection of terminals to the main processor, means that if one terminal breaks

down it wont affect other terminals.

Disadvantages of star topology


� All traffic between two nodes passes through the central node. If the central component

breaks down, the whole network is down.

� The number of ports of the central component limits the number of connected nodes.

� A star topology requires a lot of cabling since all data path connections must be to the

central node.

� There is no direct communication between or among workstations

� Sharing of processor delays in the processing of jobs.

BUS/LINEAR TOPOLOGY

� Describes a network in which each n

� This is also sometimes called a horizontal, multidrop or multi point network.

� Though it is preferable to use the last terms for connections with a mainframe/mini

computer as in the following diagram.

� In a bus messages

nodes but every node can hear each message as it goes past.

� When the signal/message reaches an end of the bus, a terminator absorbs it, to

keep it from traveling back again along the bus line,

other messages already in the line.

� The data/signals/messages are transmitted in packets along the bus.� Each packet is send with a receiver identification code

destination and all computers on the network ar

messages coming to them.

Definitions of bus network on the Web:

• A single-cable LAN, in which all computers on the network are connected in series to a

single cable. On a bus network, each computer hears all of the transmi

the line, and selects only those that are addressed to its location. This is the simplest and

most common LAN technology.

Advantages of Bus Network/topology� When a node breaks down, the network does not break down.

� A bus uses relatively

� Direct communication due to direct connection.

� Fast processing since there is no Host computer

� Once a cable has been laid down any new equipment can easily be

connected to the network by a simple tapping into the c

Disadvantages of Bus Network/topology� In a bus topology it is not always easy to add a node. [E.g. installation of extra tap in thick

Ethernet].

� Diagnosis/trouble shooting can be difficult.

� Expensive to run [several processors]

� Communication between components of the network traveling in opposite direction

along the bus can collide



All traffic between two nodes passes through the central node. If the central component

breaks down, the whole network is down.

The number of ports of the central component limits the number of connected nodes.

s a lot of cabling since all data path connections must be to the

There is no direct communication between or among workstations

Sharing of processor delays in the processing of jobs.

Describes a network in which each node is connected to a common line.

This is also sometimes called a horizontal, multidrop or multi point network.

Though it is preferable to use the last terms for connections with a mainframe/mini

computer as in the following diagram.

In a bus messages travel in both directions and do not go through the individual

nodes but every node can hear each message as it goes past.

When the signal/message reaches an end of the bus, a terminator absorbs it, to

keep it from traveling back again along the bus line, to avoid interference with

other messages already in the line.

The data/signals/messages are transmitted in packets along the bus.Each packet is send with a receiver identification code that is an address of destination and all computers on the network are permanently on the alert for any

messages coming to them.

on the Web:

cable LAN, in which all computers on the network are connected in series to a

single cable. On a bus network, each computer hears all of the transmissions going down


most common LAN technology.

Advantages of Bus Network/topology When a node breaks down, the network does not break down.

A bus uses relatively less cables compared to other topologies

Direct communication due to direct connection.

Fast processing since there is no Host computer

Once a cable has been laid down any new equipment can easily be

connected to the network by a simple tapping into the cable.

Disadvantages of Bus Network/topology In a bus topology it is not always easy to add a node. [E.g. installation of extra tap in thick

Diagnosis/trouble shooting can be difficult.

Expensive to run [several processors] – Detectors.

tion between components of the network traveling in opposite direction

collide causing loss of transmitted information.


102

All traffic between two nodes passes through the central node. If the central component

The number of ports of the central component limits the number of connected nodes.

s a lot of cabling since all data path connections must be to the

ode is connected to a common line.

This is also sometimes called a horizontal, multidrop or multi point network.

Though it is preferable to use the last terms for connections with a mainframe/mini

travel in both directions and do not go through the individual

When the signal/message reaches an end of the bus, a terminator absorbs it, to

to avoid interference with

The data/signals/messages are transmitted in packets along the bus. an address of

e permanently on the alert for any

cable LAN, in which all computers on the network are connected in series to a

ssions going down


When a node breaks down, the network does not break down.

less cables compared to other topologies

Once a cable has been laid down any new equipment can easily be

able.

In a bus topology it is not always easy to add a node. [E.g. installation of extra tap in thick

tion between components of the network traveling in opposite direction


� Because of this collision a detection system has to be present to control the re

of lost information thereby making it a more expensive option

RING NETWORK

� A ring network has nodes connected in a circular way.

� Each node has two neighboring nodes

� Data flow is unidirectional.� A message is forwarded in one direction until it reaches the destination with

intermediate nodes acting as relay [store & forward] units.

� The destination node copies the message and passes the message again to the ring.

� This message then continues to circulate around the ring back to the source.

Definitions of ring network on the • A network topology in the form of a closed loop or circle. Each node in the network is

connected to the next, and messages move in one direction around the system. When a

message arrives at a node, the node examines the address information in the mess

the address matches the node's address, the message is accepted; otherwise the node

regenerates the signal and places the message back on the network for the next node in the system. ...

Advantages of ring network � The message return provides the

The node removes its own message from the ring.

� Little cabling needed compared to Star.

� Each node acts as relay unit.

� Packet collisions do not occur because information is traveling in one

direction.

� Relatively cheap

� Efficient and accurate means of communication.

� There is no dependency on the host computer or file server as each node

controls transmission to and from itself.

Disadvantages of ring network � Adding or removing nodes disrupts the network.

� If one of the nodes breaks down, the whole network will be down.

� If the network cable breaks the whole network is affected



Because of this collision a detection system has to be present to control the re

eby making it a more expensive option

A ring network has nodes connected in a circular way.

Each node has two neighboring nodes

unidirectional. A message is forwarded in one direction until it reaches the destination with

intermediate nodes acting as relay [store & forward] units.

The destination node copies the message and passes the message again to the

This message then continues to circulate around the ring back to the source.

on the Web:

A network topology in the form of a closed loop or circle. Each node in the network is


message arrives at a node, the node examines the address information in the mess


regenerates the signal and places the message back on the network for the next node in

The message return provides the source with a form of acknowledgement.The node removes its own message from the ring.

Little cabling needed compared to Star.

Each node acts as relay unit.

Packet collisions do not occur because information is traveling in one

direction.

Relatively cheap to install.

Efficient and accurate means of communication.

There is no dependency on the host computer or file server as each node

controls transmission to and from itself.

Adding or removing nodes disrupts the network.

of the nodes breaks down, the whole network will be down.

If the network cable breaks the whole network is affected


103

Because of this collision a detection system has to be present to control the re-transmission

A message is forwarded in one direction until it reaches the destination with

The destination node copies the message and passes the message again to the

This message then continues to circulate around the ring back to the source.

A network topology in the form of a closed loop or circle. Each node in the network is


message arrives at a node, the node examines the address information in the message. If


regenerates the signal and places the message back on the network for the next node in

acknowledgement.

Packet collisions do not occur because information is traveling in one

There is no dependency on the host computer or file server as each node



TREE TOPOLOGY

Tree topologies are comprised of the multiple star topologies on a bus. Tree topologies integrate

multiple star topologies together onto a bus. Only the hub devices can connect directly with the

tree bus and each Hub functions as a root of a tree of the network devices. This bus/star/hybrid combination supports future expandability of the computer networks, much better than a bus or

star.

Advantages of a Tree Topology

• Point-to-point wiring for individual segments.

• Supported by several hardware and software venders.

Disadvantages of a Tree Topology

• Overall length of each segment is limited by the type of cabling used.

• If the backbone line breaks, the entire segment goes down.

• More difficult to configure and wire than other topologies.

LANs and WANs There are two types of network: LAN and WAN.

LAN (LOCAL AREA NETWORK) A LAN is a high-speed data network that covers a relatively small geographic area. It typically

connects workstations, personal computers, printers, servers, and other devices. LANs offer


computer users many advantages, including shared access to devices and ap

exchange between connected users, and communication between users via electronic mail and

other applications. The development of standard networking protocols and media has resulted in

worldwide proliferation of LANs throughout business an

� Typically connects computer in a single building or campus.

� Developed in 1970s.

� Medium : optical fibres,

� Low latency (except in high traffic periods).

� High speed networks (0.2 to 100 Mb/sec).

� Speeds adequate for most distr

� Problems : Multimedia based applications

� Typically buses or rings.

� Ethernet, Token Ring

A LAN is a Local Area Network covering a small area such as one building e.g. in a school or a

college.

WAN (WIDE AREA NETWORK)

A network consisting of computers of LAN's connected across a distance WAN can cover small to

large distances, using different topologies such as telephone lines, fiber optic cabling, satellite

transmissions and microwave transmissions

geographic areas. Dedicated transoceanic cabling or satellite uplinks may be used to connect

this type of network. Using a WAN, schools in Harare can communicate with places like Pretoria in

a matter of minutes, without paying enormous phone bills. A WAN is complicated. It uses

multiplexers to connect local and metropolitan networks to global communications networks like

the Internet. To users, however, a WAN will not appear to be much different than a LAN or a MAN.

� Developed in 1960s.

� Generally covers large distances (states, countries, continents).

� Medium: communication circuits connected by

� Routers forwards packets from one to another following a route from the sender to the

receiver. Store-and-Forward

� Hosts are typically connected (or close to) the routers.

� Typical latencies : 100ms � Problems with delays if using

� Typical speed: 20 - 2000 Kbits/s.

� Not (yet) suitable for distributed computing.

� New standards are changing the landscape.

A WAN is a Wide Area Network coverin



computer users many advantages, including shared access to devices and applications, file



worldwide proliferation of LANs throughout business and educational organizations.

Typically connects computer in a single building or campus.

, coaxial cables, twisted pair, wireless.

(except in high traffic periods).

High speed networks (0.2 to 100 Mb/sec).

Speeds adequate for most distributed systems

Problems : Multimedia based applications

covering a small area such as one building e.g. in a school or a



transmissions and microwave transmissions. Wide Area Networks (WANs) connect larger



ithout paying enormous phone bills. A WAN is complicated. It uses

to connect local and metropolitan networks to global communications networks like

users, however, a WAN will not appear to be much different than a LAN or a MAN.

Generally covers large distances (states, countries, continents).

Medium: communication circuits connected by routers.

Routers forwards packets from one to another following a route from the sender to the

Forward

Hosts are typically connected (or close to) the routers.

: 100ms - 500ms. Problems with delays if using satellites.

2000 Kbits/s.

Not (yet) suitable for distributed computing.

New standards are changing the landscape.

covering a large geographical area.


105

plications, file



covering a small area such as one building e.g. in a school or a



. Wide Area Networks (WANs) connect larger



ithout paying enormous phone bills. A WAN is complicated. It uses

to connect local and metropolitan networks to global communications networks like

users, however, a WAN will not appear to be much different than a LAN or a MAN.

Routers forwards packets from one to another following a route from the sender to the



Advantages and disadvantages of networks ADVANTAGES OF GROUP WORKING & SHARING RESOURCES OVER A NETWORK.

ADVANTAGES OF INSTALLING A NETWORK

1. Speed. Networks provide a very rapid method for sharing and transferring files. Without a

network, copying them to floppy disks, then carrying or sending the disks from one

computer to another shares files. This method of transferring files (referred to as sneaker-

net) is very time-consuming.

2. Cost. Networkable versions of many popular software programs are available at

considerable savings when compared to buying individually licensed copies. Besides

monetary savings, sharing a program on a network allows for easier upgrading of the

program. The changes have to be done only once, on the file server, instead of on all the

individual workstations. Low cost. Single device shared by several machines reduce the

need to buy many peripheral devices. Resource sharing also serves money. An installation

can have several low-cost work stations accessing a single file-server. That puts a lot of

processing power on the user’s desk without the expense of large mainframe systems.

3. Security. Files and programs on a network can be designated as "copy inhibit," so that you do not have to worry about illegal copying of programs. Also, passwords can be

established for specific directories to restrict access to authorized users. Security is good -

users cannot see other users' files unlike on stand-alone machines.

4. Centralized Software Management. One of the greatest benefits of installing a network at a school is the fact that all of the software can be loaded on one computer (the file

server). This eliminates that need to spend time and energy installing updates and tracking

files on independent computers throughout the building. Site licenses are likely to be

cheaper than buying several stand-alone licenses.

5. Resource Sharing. Sharing resources is another area in which a network exceeds stand-

alone computers. Some organizations cannot afford enough laser printers, fax machines,

modems, scanners, and CD-ROM players for each computer. However, if these or similar

peripherals are added to a network, they can be shared by many users. Resource sharing

is the primary benefit of networking. It allows users on different machines to share modems,

printers, tape drives and disk space, for example, users can send network messages

requesting to use a central printer, allowing everyone to share that resource. Users realize

the benefit of sharing information. Data files can be shared between machines on the

network, allowing users to see invoices, results of surveys, company newsletters, and other

information.

6. Electronic Mail. The presence of a network provides the hardware necessary to install an e-mail system. E-mail aids in personal and professional communication for all school personnel, and it facilitates the dissemination of general information to the entire school

staff. Electronic mail on a LAN can enable students to communicate with teachers and

peers at their own school. If the LAN is connected to the Internet, students can

communicate with others throughout the world.

7. Flexible Access. Networks allow data & information access from any computer in the

campus.

8. Workgroup Computing. Workgroup software (such as Microsoft BackOffice) allows many

users to work on a document or project concurrently. For example, educators located at

various schools within a county could simultaneously contribute their ideas about new

curriculum standards to the same document and spreadsheets.

9. It turns isolated computers into integrated systems, providing an environment where

resources are shared and capacity problems reduced.



10. It allows growth. If more computing resources become a need, a new computer can be

installed, added to the network, and immediately accessed by other machines and users.

11. High reliability. If applications share data, the data can be replicated across several machines. If one machine goes down, another can take its place and provide the data to

the applications.

12. A file server is easy to back up as all the data is stored in one place DISADVANTAGES Disadvantages of Installing a Network

1. Expensive to Install. Although a network will generally save money over time, the initial

costs of installation can be prohibitive. Cables, network cards, and software are

expensive, and the installation may require the services of a technician. Purchasing the

network cabling and file servers can be expensive.

2. Requires Administrative Time. Proper maintenance of a network requires considerable

time and expertise. Many organizations have installed a network, only to find that they did

not budget for the necessary administrative support.

Increased administration. There will be need for a systems administrator to tune the

network, monitor the network, administer database files, and ensure network integrity (ensure the network runs smoothly)

3. File Server May Fail. Although a file server is no more susceptible to failure than any other

computer, when the files server "goes down," the entire network may come to a halt.

When this happens, the entire school may lose access to necessary programs and files.

4. Cables May Break. Some of the configurations are designed to minimize the

inconvenience of a broken cable; with other configurations, one broken cable can stop

the entire network.

5. Security concerns. Some user can gain unauthorized access to private data. There is a

danger of hacking, particularly with wide area networks. Security procedures are needed to prevent such abuse. Of all the disadvantages, the greatest drawback is security

concerns; therefore, network security is a priority in the development of network

applications.

6. Network failure. As applications increase their use of a network, network failures become

catastrophic.

7. Virus attack. A networked system is vulnerable to destructive network messages. For

example, a message that sparks damaging activity (like erasing files) may enter the

system via the network.Viruses can spread to other computers throughout a computer

network.

8. Managing a large network is complicated, requires training and a network manager

usually needs to be employed.

9. If the file server breaks down the files on the file server become inaccessible. E-mail might

still work if it is on a separate server. The computers can still be used as stand alones.

Network Security

The field of network security in general and of TCP/IP security in particular is too wide to be dealt with we take the most common security exposures and measures to counteract them. Because

many, if not all, security solutions are based on cryptographic algorithms.

Security Issues This section gives an overview of some of the most common attacks on computer security, and it

presents viable solutions to those exposures and lists actual implementations.



Common Attacks For thousands of years, people have been guarding the gates to where they store their treasures

and assets. Failure to do so usually resulted in being robbed, neglected by society or even killed.

Though things are usually not as dramatic anymore, they can still become very bad. Modern day

I/T managers have realized that it is equally important to protect their communications networks

against intruders and saboteurs from both inside and outside. We do not have to be overly

paranoid to find some good reasons why this is the case:

� Tapping the wire: to get access to clear text data and passwords

� Impersonation: to get unauthorized access to data or to create unauthorized e-mails,

orders, etc.

� Denial-of-service: to render network resources non-functional

� Replay of messages: to get access to and change information in transit

� Guessing of passwords: to get access to information and services that would normally be

denied.

� Guessing of keys: to get access to encrypted data and passwords (brute-force attack,

chosen cipher text attack, chosen plaintext attack)

� Viruses, Trojan horses and logic bombs: to destroy data

Though these attacks are not exclusively specific to TCP/IP networks, they should be considered

potential threats to anyone who is going to base his/her network on TCP/IP, which is what the

majority of enterprises, organizations and small businesses around the world are doing today.

Hackers (more precisely, crackers) do likewise and hence find easy prey.

Observing the Basics Before even thinking about implementing advanced security techniques such as

the ones mentioned in the following sections, you should make sure that basic

security rules are in place:

� Passwords: Make sure that passwords are enforced to be of a minimum length (typically six to

eight characters), to contain at least one numeric character, to be different from the user ID

to which they belong, and to be changed at least once every two months.

� User IDs: Make sure that every user has a password and that users are locked out after several

logon attempts with wrong passwords (typically five attempts). Keep the passwords to

superuser accounts (root, supervisor, administrator,etc.) among a very limited circle of trusted

system, network and security administrators.

� System defaults: Make sure that default user IDs are either disabled or have passwords that

adhere to the minimum requirements stated above. Likewise, make sure that only those

services are enabled that are required for a system to fulfill its designated role.

� Physical access: Make sure that access to the locations where your systems and users

physically reside is controlled appropriately. Information security begins at the receptionist, not

at the corporate firewall.

� Help desk: Make sure that callers are properly identified by help desk representatives or system

administrators before they give out "forgotten" passwords or user IDs. Social engineering is

often the first step to attack a computer network.

Solutions to Security Issues Therefore, a combination of several such solutions should be considered in order to guarantee a

certain level of safety and security.

� Encryption: to protect data and passwords

� Authentication and authorization: to prevent improper access

� Integrity checking and message authentication codes (MACs): to protect against the

improper alteration of messages



� Non-repudiation: to make sure that an action cannot be denied by the person who

performed it

� Digital signatures and certificates: to ascertain a party's identity

� One-time passwords and two-way random number handshakes: to mutually authenticate

parties of a conversation

� Frequent key refresh, strong keys and prevention of deriving future keys: to protect against

breaking of keys (crypto-analysis)

� Address concealment: to protect against denial-of-service attacks

� Content inspection: to check application-level data for malicious content before

delivering it into the secure network

What is the Internet? � The Internet is the network of networks being a worldwide collection of computers that

communicate with one another over cables, satellites and optical fibers. It is literally the

whole hardware mass. The Internet is the network used to transport information.

Internet, by definition is a network of networks that interact with each other through exchange

of data packets. The Internet hosts an enormous information base and carries numerous

information resources and services..

� When we refer to the Internet we are usually talking about the World Wide Web (WWW)

which is the most used feature of the Internet.

� The WWW stores millions of web pages on web servers. These pages can contain text, pictures, movies, animation and sound. Web pages are written in a language or code

called HTML (Hypertext Markup Language). A set of web pages is called a website.

� Each web page has its own unique address or URL. The URL will have the format "http" and

a domain (such as ."co.uk"). What goes in between is arbitrary, but often has the term

"www "such as in "http://www.name.co.uk". but it doesn’t have to (e.g. http://news.bbc.co.uk).

� Most sites have a page that links the user to the other main areas of the site. This is called

the homepage. � Web pages are connected by hypertext links. When a link is clicked you will be taken to

another page which could be on another server in any part of the world.

� When you move around web pages you are said to be surfing the net. For this you need a program to read the pages (called a browser), such as Firefox or Internet Explorer.

� To search for a particular item or topic on the net you use a search engine. There are many different kinds of search engine, each using slightly different ways of searching and

indexing web content. Google, MSN and Alta Vista are all examples of search engines,

while Yahoo and Excite are web directories (a bit like the Yellow Pages phone book) which have a search function built in.

� The World Wide Web Is software that runs on the internet which includes all documentation

that is shared and accessed on the internet.

� A Web page is a document designed to be accessed and read over the WWW. It must

have an address in a recognized format.

DEFINITION OF TERMS ISPs (Internet Service Providers)

• An ISP is a company that provides access to the Internet to individuals or companies. ISPs provide local dial-up access from your personal computer to their computer network and

their network connects you to the Internet.

• An institution (usually a private company) that provides access to the Internet in some

form, usually for money.

• A business that delivers access to the Internet.



• Are the companies who provide you with access to the internet. Commonly used ISPs in

Zimbabwe are:

1. PowerTel

2. ZOL

3. Africom

4. Ecoweb

5. Telecel

6. Comone

7. BSAT

8. Brodacom

9. Mweb

Most offer the same basic package of Internet access, email addresses, web space for your own pages and local rate call charges.

Browser or web browser

• A web browser is a software application that enables a user to display and interact with HTML documents hosted by web servers or held in a file system. Popular browsers

available for personal computers include Microsoft Internet Explorer, Mozilla Firefox,

Opera, and Safari. A browser is the most commonly used kind of user agent. The largest

networked collection of linked documents is known as the World Wide Web.

• Is a program that allows you to view the pages on the Web? The most widely used are

1. Internet Explorer

2. Mozilla Firefox

3. Google chrome

4. Opera

5. Safari

All browsers will have a number of similar features to help you use the Web:

• Forward and back buttons to move between pages

• A history folder which stores details of recently visited web pages

• A stop button if a page is taking too long to load

• Favorites and bookmark options to store often visited pages

• Options to cut, copy, save and print the information viewed

Search engines • Internet search engines help users find web pages on a given subject. The search engines

maintain databases of web sites and use programs (often referred to as "spiders" or "robots") to

collect information, which is then indexed by the search engine. Similar services are provided

by "directories," which maintain ordered lists of websites, eg Yahoo!

• Examples of search engines are: Google, MSN, Bing, Yahoo, AltaVista

Internet address • The numbering system used in TCP/IP internetwork communications to specify a particular

network or a particular host on that network with which to communicate. Internet addresses

are commonly denoted in dotted decimal form.

Examples of internet addresses

1. www.facebook.com

2. www.google.com

3. www.yahoo.com

4. www.gmail.com

5. www.herald.co.zw

• An IP address (Internet Protocol address) is a unique number, a kind of telephone number,

used by machines (usually computers) to refer to each other when sending information

through the Internet. This allows machines passing the information onwards on behalf of the

sender to know where to send it next, and for the machine receiving the information to know

that it is the intended destination.

List of Internet Terminology

ARPANET: The acronym stands for Advanced Research Projects Agency Network. ARPA of the

United States Department of Defense developed ARPANET, which became the world's first packet

switching network. Internet is the successor of ARPANET.



Internet Service Provider: A company, which provides users with an access to the Internet, is known

as an Internet service provider or Internet access provider. ISP, as it is called, offers email accounts

and other services like remote storage of files for its customers.

OSI Model: The Open System Interconnection Model is used to describe a layered communication

and network protocol design of a network. It is composed of seven layers, each of which performs

certain functions and provides the layers above it with some services. Go through an elaborate

description of the OSI model.

Internet Protocol Suite: It is a set of communication protocols, which are used for the Internet.

Transmission Control Protocol (TCP) and Internet Protocol (IP) were the two pioneering protocols to

be introduced in the Internet protocol standard. The Internet protocol suite is composed of a set of

layers wherein; each layer provides a service to the upper layers in the set. The upper layers deal

with abstract data while the lower layer protocols translate data into physically transmittable forms.

PPP: Point-to-Point protocol (PPP) is a data link protocol that facilitates the establishment of a direct

connection between two nodes on a network. Here is a brief introduction to the Point-to-Point-

protocol.

IP Address: It is a way of numerically identifying an entity on a computer network. The original addressing system known as IPv4, used 32 bit addresses. With the growth of the Internet, IPv6 came

to be used wherein the addresses are composed of 128 bits. You might want to know how to find

your IP address.

MAC Address: Media Access Control address (MAC) is the physical hexadecimal address assigned

to each device on a network.

Domain Name System: DNS, as it is called, refers to the hierarchical naming system used for

computers, resources and services on the Internet. It translates the computer hostnames to IP

addresses. By way of the implementation of DNS, the domain name 'www.buzzle.com' translates to

its IP address, say, 208.70.178.150. With the help of DNS, domain names can be assigned to Internet

users.

Cyberspace: This term coined by William Gibson, is used to refer to the computer networks

connected to each other and the content they host. It is often used to refer to the Internet.

WWW: It is a collection of interlinked documents that are accessible over the Internet. It consists of

millions of web pages that contain text, images, voice and videos. Sir Tim Berners-Lee, a British

scientist working at CERN, created the World Wide Web.

W3C: It is the acronym used for the World Wide Web Consortium, which develops standards for the

web community.

Website: A website is a set of web pages consisting of text, audio and video. Web servers host

websites.

URL: It specifies the location of a resource on the Internet. It consists of the basic address and path.

Web Page: Web pages are resources of information. They are generally created in the HTML format

and provide the web users with navigational abilities through hyperlinks to other web pages on the

web.

Home Page: The term home page is used to refer to the page that is the default page of any

website. It is the main page of a complex website.

Proxy Server: Client machines on a network connect to the proxy server, which forwards the client

requests to other servers and returns responses to the clients.



Web Server: A web server is a computer program that accepts HTTP requests from web clients and

provides them with HTTP responses.

Web Browser: A web browser is a software application that facilitates user interaction with the text, audio, video and other information that is located on the web.

Cache: Web browsers maintain a cache of recently visited web pages. Some of them use an

external proxy web cache, which is a server program through which web requests pass. This

enables the browsers to cache frequently visited pages. Even search engines make available

already indexed web pages through their caches.

HTTP: Hypertext Transfer Protocol, abbreviated as HTTP, is a communications protocol used for the

transfer of information over the Internet. A client makes an HTTP request using a web browser to

which an HTTP response is sent from the server.

Web Cookie: Also known as an HTTP cookie, it is piece of text that is exchanged between the web client and the web server. It is sent by the web server to the web client and returned unchanged

by the client each time it accesses the server. You might want to know how do websites use

cookies?

Session: It is an exchange of information between a computer and its user. It is established for a

certain period of time after which it ends.

Hyperlink: A reference in a document to another section of the document or to another

document is termed as a hyperlink. Hyperlinks are used to redirect the user from one section of a

page content to another.

Web 2.0: It is used to describe the changes in the www technology and web design. The term

deals with the idea of the development of interactivity and connectivity of the web content.

Internet security: It is one of the major concerns today. As the Internet acts as a communication

platform that can be accessed by millions of users around the world, it becomes necessary that

proper measures be implemented. Issues like Internet safety that deal with the content that is

made accessible over the Internet are equally important. Internet privacy relates to safeguarding

the privacy of the web users and the sensitive information on the web from hackers and stalkers.

Internet - A communication Platform

Internet serves as one of the most efficient means of communication. Computers from different

parts of the world can be connected to each other to exchange information, thanks to the

Internet. Emails and chats are excellent means of communication over the Internet. Blogs and

online forums give the Internet users a platform to reach out to the masses. Here is a list of the basic

Internet terms associated with the Internet as a communication platform.

Email: It is a store-and-forward method of writing, sending and receiving written messages.

Electronic mail is an Internet e-mail system that uses network-based protocols to exchange

messages between network subsystems.

Email Address: It identifies the network location to which an email can be delivered. An email

address is a combination of the user name of the mail user and the host name of the mailing

system. It is of the form, 'username@domain-name'. An email alias is a forwarding email address. It

simply forwards emails to specific email addresses.

Spamming: The act of sending unsolicited bulk messages over an email system is known as

spamming. It is an undesirable use of the electronic messaging systems.

Phishing: It is a fraudulent activity of acquiring the sensitive information by the use of a fake identity

during electronic communication. It is implemented by means of emails and instant messages

wherein a user is lured to enter his/her details, which are actually captured by a fraudulent



website.

Hacking: Hacking is the activity of programmatically gaining access to a computer application

that is otherwise inaccessible. The act of gaining an unauthorized access to a computer is known

as hacking. Hacking of passwords that leads to breach of email privacy is a threat to

communication over the Internet. Internet crime refers to all the criminal activities that are carried

over the Internet.

Email Scams: With the increase in the use of email systems, its security needs also rose. Fraudulent

users started tampering with the email systems to breach security.

Email Virus: It is a computer code that is transmitted through an email in the form of an

attachment. The email attachment causes the destruction of some of the files on the receiver

computer's hard disk and is programmatically emailed to the contacts in the address book of the

receiver.

Email Client: It is also known as a mail user agent (MUA). An email client is a front-end computer

program or an agent that acts as a client for the email server.

Mail Server: It can also be called Mail Transfer Agent (MTA) and is responsible for receiving incoming email from local users and forwarding outgoing mails for delivery. A mail server

application forms the heart of a messaging system that performs all the functions to keep the mails

moving over the network.

SMTP: Short for Simple Mail Transfer Protocol, SMTP is the standard for the transmission of electronic

mails. The electronic mail server software uses SMTP to send and receive mail messages. ESMTP,

that is known as extended or enhanced SMTP refers to the protocol extensions made to SMTP and

is widely used today.

POP3: Short for Post Office Protocol, POP3 is an application layer Internet standard protocol. It is used to retrieve mails from a remote server. Here is a brief introduction to POP3.

IMAP: Internet Message Access Protocol, as it is called, is another Internet standard protocol used

for retrieval of emails.

Internet Chat: It is a real-time Internet chat or synchronous conferencing that is used for group

communication as well as one-to-one communication over the Internet. Jarkko Oikarinen, a Ph.D.

from the University of Oulu is the developer of the first Internet chat network. He developed the

client and server programs for Internet Relay Chat in August 1988.

Social Networking: Social networking is about building online communities of like-minded people.

Serving as an excellent platform for sharing of information, social networking is a rage today.

ADSL: Asymmetric Digital Subscriber Line, abbreviated as ADSL, is used for the transmission of digital

information using high bandwidths on existing phone lines. ADSL technology is characterized by

high download and low upload rates.

Dial-up: It is the means to connect to the Internet using the copper phone lines and a modem.

Dial-up connections are capable of sending information from the client's end at very slow speeds

of about 56kbps.

Modem: It is a device that modulates analog carrier signals to encode digital information and

demodulates carrier signals to decode information. A cable modem provides access to data

signals sent over the cable television infrastructure. Modems are commonly used for facilitating

Internet access.

Communication Bandwidth: It refers to the data that can be transferred between two points in a given period of time. It is expressed in terms of bits per second. It is commonly known as the bit



rate.

Blogs: Blogs are the expressions of the common masses about social or political issues or simply

anything. Blogs can often be in the form of creative write-ups by writers in different parts of the

world.

Internet Forums: It is a bulletin board that serves as a platform for group discussion. Registered users

are free to contribute to the issues raised in forums thus making them open discussion platforms.

Usenet: Usenet can be considered as a worldwide bulletin board. Usenet newsgroups serve as a repository of messages posted from users around the world.

Internet - A Search Platform

Internet that hosts an ocean of information has also become an excellent platform for information

retrieval. The Internet search engines, which crawl and index web pages, organize the information

on the Internet and the web directories link to information on the network. Here is a list of the

Internet terms related to the Internet as a search platform.

Internet Search Engine: It is an information retrieval system that is designed to help find information

over the Internet. Search engines use algorithms to scan the huge information base of the Internet and sort it making it retrievable for the web users.

Web Crawler: Popularly known as a spider, a web crawler is a program that browses the World

Wide Web in an automated manner. Search engines use the crawling technologies to index pages

on the web.

Search Engine Optimization: The process of organizing the content of a website with intent to increase its relevance with respect to keywords and search engines. The process of optimization

involves editing website content and HTML coding to support search engine strategies of ranking

and indexing.

Internet Bookmark: The Internet browsers of the modern times aim at enabling the users to organize

the web pages they access. Links once visited can be saved in the favorites or preferences

categories. Bookmarks are usually integrated into browsers. Social bookmarking is a method used

by Internet users to store and manage web pages.

Web Directories: It is a directory, which links to other websites and organizes those links. They should not be mistaken as being search engines.

OTHER TERMS

Router: A router connects two or more logical subnets and performs the functions of routing and

forwarding information.

Intranet: It is a relatively smaller private network that uses the Internet protocols and connectivity. It

is an extension of the Internet and is privately used by organizations.

Extranet: It is a private network that uses Internet technology to share a part of the business information and operations with suppliers and customers. It can be a part of a company's intranet

that provides access to the users outside the company.

Virtual Private Network: It is a private network that allows the exchange of information between

computers over a shared or a public network.

Wireless Networking: It refers to computer networking that is carried out over the wireless media.

Broadband Internet: Broadband connectivity to the Internet provides the users with a high-speed Internet access.



Dial-up Internet: In this type of access to the Internet, the user's computer is attached to a modem

connected to a telephone line. Dial-up Internet access involves a modem that dials into an

Internet service provider to establish a connection.

Satellite Internet: Internet services that make use of the satellite communication media are termed

as satellite Internet services. They are used in locations that are mobile thus making terrestrial

Internet connectivity, an impossibility.

Some Funny and Interesting Internet Terms

Googling: The Google search engine, being the most popularly used one, has made the word,

'google' synonymous to the concept of search engines. Searching the Internet by using the

Google search engine is known as googling.

Copypasta: If text is copy pasted from somewhere and posted in a forum, it is termed as a

copypasta. The source is often unknown in such cases.

Egosurfer: The web users who search over the Internet for themselves fall under the class of

egosurfers. I am sure most of you play an egosurfer once in a while.

Netiquette: This term is short for net etiquette and refers to the principles of courtesy and

consideration for the people using the Internet. It refers to certain basic principles to adhere to

while using the Internet. The general ethical principles to be followed in relation to using mailing

systems of the Internet are termed as email etiquette.

Trasher: The users who search over the Internet using all possible means, sometimes even risking the

Internet security are known as trashers.

Troll: Trolls are the users who try to become infamous on chat by introducing disturbing links,

mimicking other users' posts and profiles and fighting with others.

Youtuber: A person who is addicted to watching videos on the Internet is referred to as a youtuber What are the advantages & disadvantages of the Internet? Discuss These are far too broad and extending to all realms in life. For instance:-

1) Access to a wide range of information from any location worldwide where there is

internet access. i.e. airlines, resorts, books, authors.

2) Research on any topic i.e. a professor, current affairs.

3) Online Shopping i.e. for cars, specific dress. 4) Online ordering and carrying out other business transactions e.g.. Ordering a cheque

book, advertising a product.

5) Online conferencing – communicating across international boundaries.

6) Ability to access e-mail from any location worldwide.

7) Reading newspapers online.

Advantages

Faster Communication The foremost target of Internet has always been speedy communication and it has excelled way

beyond the expectations. Newer innovations are only going to make it faster and more reliable.

Now, you can communicate in a fraction of second with a person who is sitting in the other part of

the world. For more personal and interactive communication, you can avail the facilities of chat

services, video conferencing and so on. Besides, there are plenty of messenger services in offering.

With the help of such services, it has become very easy to establish a kind of global friendship



where you can share your thoughts and explore other cultures.

Information Resources Information is probably the biggest advantage that Internet offers. Internet is a virtual treasure

trove of information. Any kind of information on any topic under the sun is available on the Internet.

The search engines like Google, Yahoo are at your service on the Internet. There is a huge amount

of information available on the Internet for just about every subject known to man, ranging from

government law and services, trade fairs and conferences, market information, new ideas and

technical support, the list is simply endless.

Students and children are among the top users who surf the Internet for research. Today, it is almost

required that students should use it for research or the purpose of gathering resources. Even

teachers have started giving assignments that require extensive research on the Internet. Besides,

you can have an access to latest researches in the field of medicine, technology and so on.

Numerous web sites such as America's Doctor also allow you to talk to the doctors online.

Entertainment Entertainment is another popular raison d'être why many people prefer to surf the Internet. In fact,

the Internet has become quite successful in trapping the multifaceted entertainment industry.

Downloading games or just surfing the celebrity websites are some of the uses people have discovered. Even celebrities are using the Internet effectively for promotional campaigns. Besides,

there are numerous games that can be downloaded for free. The industry of online gaming has

tasted dramatic and phenomenal attention by game lovers.

Social Networking One cannot imagine an online life without Facebook or Twitter. Social networking has become so

popular amongst youth that it might one day replace physical networking. It has evolved as a

great medium to connect with millions of people with similar interests. Apart from finding long-lost

friends, you can also look for job, business opportunities on forums, communities etc. Besides, there

are chat rooms where users can meet new and interesting people. Some of them may even end

up finding their life partners.

Online Services The Internet has made life very convenient. With numerous online services you can now perform all

your transactions online. You can book tickets for a movie, transfer funds, pay utility bills, taxes etc.,

right from your home. Some travel websites even plan an Itinerary as per your preferences and

take care of airline tickets, hotel reservations etc.

e-commerce The concept of e-commerce is used for any type of commercial maneuvering or business deals

that involves the transfer of information across the globe via the Internet. It has become a

phenomenon associated with any kind of shopping, business deal etc. You name a service, and e-

commerce with its giant tentacles engulfing every single product and service will make it available at your doorstep. Websites such as eBay allow you to even bid for homes, buy, sell or auction stuff

online.

Additional advantages

1. Global Audience Content published on the World Wide Web is immediately available to a global

audience of users. This makes the World Wide Web a very cost-effective medium to

publish information. Reaching more than 190 countries.

2. Operates 24 hours, 7 days a week You don't need to wait until resources are available to conduct business. From a

consumer's perspective as well as a provider's business can be consummated at any

time. The fact that the Internet is operational at all times makes it the most efficient

business machine to date.



3. Relatively Inexpensive It is relatively inexpensive to publish information on the Internet. At a fraction of the

cost to publish information by traditional methods, various organizations and

individuals can now distribute information to millions of users. It costs only a few

thousand dollars to establish an Internet presence and publish content on the Internet.

4. Product Advertising You can use the World Wide Web to advertise various products. Before purchasing a

product, customers will be able to look up various product specification sheets and

find out additional information. You can use the multimedia capabilities of the World

Wide Web to make available not only various product specification sheets but also

audio files, images, and even video clips of products in action. The beauty of the Web

is that it allows customers to explore products in as much detail as they desire. If the

client just wants a general overview, he or she can look at the advertising information.

For those wanting more in depth information, you can provide white papers and

product descriptions for download. The Web allows a business to provide timely

information, you can simply place the information on the Web page and it is available

immediately for your customers.

5. Distribute Product Catalogs The World Wide Web is a very effective medium for distributing product catalogs. In

the old days, putting together a product catalog used to be very costly in terms of time and money needed to publish and distribute it. The World Wide Web changes all

this by allowing content developers to put together a sales catalog and make it

available to millions of users immediately. Furthermore, unlike printed product

catalogs that are usually updated around once a month, product catalogs on the

World Wide Web can be updated as needed to respond to various changing market

conditions.

6. Online Surveys Traditional methods of performing surveys are often relatively slow and expensive

compared to online surveys conducted on the Internet. For example, in order to fill out

various needs of customers or what they would like to see in a future product, it's often

necessary to compile a list of address and mail a questionnaire to many customers.

The success of such an attempt is not always guaranteed and can be very costly in

terms of mailing the questionnaires and entering responses to a databases and

analyzing it. On the other hand, you can use the World Wide Web to automate the

whole process. For example, you can set up a CGI script to conduct online surveys.

Results of such a survey can be automatically updated to a database. This database

can then be used to keep a pulse on various opinions and needs of customers.

7. Announcements With the World Wide Web, you can distribute various announcements to millions of

users in a timely manner. Because there is virtually no time lag from the time it takes to

publish information to making the information available to users, the Web is an ideal

medium to publicize announcements. As more people discover the virtues of the Web

and get connected to the Internet, the Web will become the medium of choice for many organizations and individuals to publicize various announcements.

8. Provide Technical Support You can also use Web site to provide technical support to users. Because Web pages

can be updated immediately with new information, various technical support

literature can be immediately modified in light of new findings and developments. This

can be accomplished without having to distribute changes to all users affected by

any changes using traditional mediums of information distribution, which are often

quite costly compared to the World Wide Web.

9. Create Online Discussion Forums By using applications such as WebBoard, it's possible to set up online discussion forums

on the Web.

10. Obtain Customer Feedback The interactive nature of the World Wide Web is ideal for obtaining customer

feedback. You can easily set up a CGI script to obtain customer feedback about a

product or service. Because customer feedback submitted by customers can be read



immediately, it's possible to respond to various customer concerns in a timely manner,

increasing customer satisfaction and quality of customer service.

11. Immediate Distribution of Information When information is added to a Web site, it's immediately available for browsing by

millions of Internet users. The World Wide Web is an ideal medium of information

distribution because it takes away the time lag associated with publishing content and

actually making it available to users

12. Easy Integration with Internal Information Systems Internet information systems deployed on the Internet can be easily integrated with

internal information systems managed with office productivity applications such as

Microsoft Office.

13. Powerful Content Publishing Tools A new breed of Internet aware applications will start emerging in software stores by

the time you read this. These applications will enable users to develop content for the

World Wide Web by simply saving as an HTML file. In addition to software developers

making existing applications Internet aware, various new, powerful, and easy-to use

Internet content publishing applications are also being developed. These applications

will make the task of publishing content on the Internet even easier. Most of these

applications are developed for Windows users.

14. Multimedia The capability to incorporate multimedia into Web pages is a major advantage of

using World Wide Web to publish information. For example, many Web sites use sounds

and video clips to make the content easier and more interesting to browse.

15. Formatting Capabilities Content published on the World Wide Web can be richly formatted by using various

HTML tags and graphic formats. The capability to do this is a major reason for the

success of the World Wide Web. In addition to using HTML tags and various multimedia

formats in Web pages, various interactive controls can also be added to a web page.

This capability allows Web site content developers to create "active" Web sites. For

example, before a user sends some information to a Web server for processing, a

VBScript or JavaScript subroutine can be used to verify information typed in by the

user. Various formatting capabilities, along with technologies such as Java and

VBScript, make the World Wide Web a richly interactive medium that you can use to

distribute information to millions of users.

Disadvantages

Theft of Personal Information If you use the Internet for online banking, social networking or other services, you may risk a theft to

your personal information such as name, address, credit card number etc. Unscrupulous people

can access this information through unsecured connections or by planting software and then use

your personal details for their benefit. Needless to say, this may land you in serious trouble.

Spamming Spamming refers to sending unwanted e-mails in bulk, which provide no purpose and needlessly

obstruct the entire system. Such illegal activities can be very frustrating for you as it makes your

Internet slower and less reliable.

Virus Threat Internet users are often plagued by virus attacks on their systems. Virus programs are inconspicuous

and may get activated if you click a seemingly harmless link. Computers connected to the Internet

are very prone to targeted virus attacks and may end up crashing.

Pornography



Pornography is perhaps the biggest disadvantage of the Internet. Internet allows you to access

and download millions of pornographic photos, videos and other X-rated stuff. Such unrestricted

access to porn can be detrimental for children and teenagers. It can even play a havoc in marital

and social lives of adults.

Social Disconnect Thanks to the Internet, people now only meet on social networks. More and more people are

getting engulfed in virtual world and drifting apart from their friends and family. Even children

prefer to play online games rather than going out and mingling with other kids. This may hamper a

healthy social development in children

The Web uses three standards namely: 1 URLs (Uniform Resource Locators) – which are web page addresses

2 HTTP (Hypertext Transfer Protocol) – the language used to design web pages

3 HTML (Hypertext Markup Language)

To send e-mail access the Internet, both the sender and receiver need:

WHAT IS NEEDED FOR INTERNET AND E-MAIL SERVICES

1) A computer connected to a network,

2) The windows operating system installed

3) The communication and or browser software such as Ms-Exchange or Ms-Outlook,

Internet explorer, Netscape navigator

4) A modem

5) Telephone line

6) Subscription to an ISP (Internet Service Provider).

What do you need to get connected?

To connect to the internet you need:

1) A computer

2) A telephone line

3) A modem - the type of modem you need to use is dependant on the type of

connection you have. Some of the choices are:

An analogue modem and an ordinary phone line. This type of modem links your

computer to the phone and converts computer signals to analogue phone line

signals - and back again. Typical analogue modem speeds are 56Kbps (bps stands for bits per second) which means they can receive about 6000 characters

per second. This is the slowest and oldest type of connection and becoming less

common with the introduction of broadband.

An ISDN line and terminal adaptor. This digital connection is slightly faster than an

analogue connection.

An ADSL or cable telephone line and broadband modem. Broadband modems

are much faster than the other two options and their use is increasing.

4) An account with an ISP (Internet Service Provider)

5) Browser software

ISPs are the companies who provide you with access to the internet. Commonly used ISPs include

Freeserve, AOL, Virgin, Tesco, BT and many more. Most offer the same basic package of Internet

access, email addresses, web space for your own pages and local rate call charges.



A browser is a program that allows you to view the pages on the Web. The most widely used are

Internet Explorer and Firefox.

All browsers will have a number of similar features to help you use the Web:

• Forward and back buttons to move between pages

• A history folder which stores details of recently visited web pages

• A stop button if a page is taking too long to load

• Favorites and bookmark options to store often visited pages

• Options to cut, copy, save and print the information viewed

Electronic mail Electronic mail or email is a means of sending messages, text, and computer files between

computers via the telephone network. Because the telephone network covers the whole world,

email enables you to communicate world wide.

Email and web mail Email To set up email you need:

• A computer

• An internet connection via an analogue modem (ordinary phone line) or terminal adaptor (ISDN) or broadband modem (ADSL and cable)

• An account with an ISP (Internet Service Provider)

• Email software

Your Internet Service Provider will give you an email account, a password and a mailbox such as [email protected]. You can also set up an email account with a mailbox and passwords

with non-ISPs such as Google and Hotmail.

With a dial-up connection, you have to pay the cost of your internet phone calls (local rate), and

in most cases a subscription to your provider (though some are free). A broadband connection is

'always on', with only a flat-rate subscription. Very few people pay by the minute nowadays and

the majority of people pay a monthly fee for broadband access.

Anti-virus scanning is becoming standard on email accounts and many email providers now offer

an anti spam (electronic junk mail) service.

Web mail Web mail, as its name suggests, is web-based email. To use web mail, you do not need any email

software - just a computer connected to the internet via any one of the connection types listed

above, and a browser.

Users simply sign up to the web mail service of a web portal such as MSN or Yahoo. They are given

a unique user name and a personal mailbox on the portal's email server, and they can then send

and receive messages via a special web page.

A basic web mail account is usually free, although this will have a very limited amount of storage.

The advantage of web mail is that users can receive and send mail from any computer in the

world with internet access. If you have a dial-up connection you can download your emails and

then read them offline to avoid staying on-line for long periods.

Some ISPs will enable their regular email customers to access their mailbox via web mail as well as

through the email software on their PC.

Features of email • Automatic reply to messages

• Auto forward and redirection of messages

• Facility to send copies of a message to many people

• Automatic filing and retrieval of messages

• Addresses can be stored in an address book and retrieved instantly

• Notification if message cannot be delivered

• Automatically date and time stamped

• Signatures can be attached

• Files, graphics or sound can be sent as attachments, often in compressed formats

• Web mail and mobile email can be used to receive and send messages while on the move.



Using email • Broadband email

- Your connection is always on - so simply write and address your message and hit 'send' to

send your mail and 'receive' to download any incoming messages from your email

provider's server.

• Web mail - Connect to the internet (if using a dial-up account) and open your browser. - navigate to your web mail provider's portal and enter your user-name and password.

- all incoming mail will now be visible, and you can also compose and send mail, and

download attachments to your computer.

- When you're done, log out and close your connection.

• Dial-up email - Prepare your message offline as typing your message online will increase phone charges. - Connect to the internet and log on to your email account.

- Send your message and download any incoming mail sitting on your service provider's

computer.

- Log off and close your connection. Email is evolving...

• Many mobile phones already allow messages to be sent to the recipient's email inbox while the sender is on the move. The latest generation of mobile phones enables users to

send and receive wireless email in exactly the same way as a static computer.

• Email can be sent and received via digital TV, specially adapted phones, public kiosk terminals and the latest generation of games console.

• A spreading network of wireless 'hotspots' in public places allows people to send and receive email via laptop computers.

• A new range of in-car phones will enable motorists to check their email on the road

Benefits and concerns of using email

Email benefits • Fast delivery of your message

• Available 365 days, 24 hours per day - and, with web mail, wherever you are in the world as long as you have access to the internet.

• Cheap: when using broadband, individual mail transfers are effectively free. When going online from a dial-up account, calls are charged at local rates and (for conventional

email) need only last a few seconds.

• Facility to send the same message to more than one person

Email concerns • It can only be sent to people who themselves have access to the internet.

• Viruses are easily spread via email attachments - anti virus measures must be in place to avoid this and are now offered by many e-mail providers.

• Phishing - sending an e-mail to a user falsely claiming to be a legitimate company to scam the user into providing information such as personal information and bank account

numbers on a bogus website. The details will then be used for identity theft.

• No guarantee the mail will be read until the user logs on and checks their mail.

• Spam! Or Junk mail

HEALTH AND SAFETY

HEALTH PROBLEMS ASSOCIATED WITH COMPUTER USE AND POSSIBLE SOLUTIONS

Are Computers a Health Hazard? The first thing to know is that the risks are not likely to affect you unless you are a "habitual" computer user. In other words, you're sitting at the computer pretty much all day, every day. Oh

yeah... that's all of us! That's not to say that the occasional computer user won't have problems.

Everyone's level of sensitivity is unique.



The buzz started in the 80's and culminated in the 1992 Health and Safety DSE (Display Screen

Equipment) regulations. Then came Carpal-Tunnel Syndrome followed by ergonomics. The hype

has subsided, since we all know the computer isn't going to kill us - but we have learned a lot over

the past 20 years about potential health risks and more importantly, we've learned ways to avoid

being at risk when we're using computers.

Let's look at some of the most common medical problems and what you can do to avoid them.

1. Eye Strain:

• Position your terminal at right angles to the window if possible; avoid facing directly into bright light (coming at you from behind your computer screen).

• Install an anti-glare screen.

• Adjust the brightness controls on the screen until they are comfortable to your eyes. 2. Carpal Tunnel Syndrome:

• Adjust your chair or table height to have your elbow angle at 90-100 degrees.

• Position your keyboard so that you don't have to bend your hands uncomfortably upward to reach the keys; place a raised wrist rest on the table in front of the keyboard if

necessary.

• Clinch your fists, hold for one second, then stretch your fingers out wide and hold for 5

seconds.

• Organize your workday, if possible, to intersperse other tasks with your computer work so that you're not sitting at the computer for several hours without a break. Variety is key.

• Hold the mouse loosely and click lightly. 3. Neck and Back Strain:

• Check your posture - sit up straight. Thanks Mom.

• The monitor screen surface should be approximately 18-24 inches away from your torso.

• Preferably chairs should be on wheels, have backrest tilt adjustment, and have arms.

• Be sure you have enough desktop space for work papers and other equipment. 4. Conjunctivitis (itchy, bloodshot eyes) and Dermatitis:

• Be sure the screen doesn't flicker or wave - this could indicate that service or adjustment is needed.

• Look away from the screen periodically.

• Don't forget to blink - your eyes need the moisture. 5. The vision disorder Due to excessive computer use has been identified as Computer Vision Syndrome. Symptoms are

dry eyes, headaches, blurred vision, eyestrain, and shoulder back pain.

• To alleviate the problem it is suggested that computer users take regular

breaks, blink their eyes frequently, occasionally close their eyes for a few

minutes and every fifteen minutes or so look away from the computer to

stare at an object in the distance.

6. For the back pain and other muscular related problems, It is suggested that people get up every hour, stretch and move around for about five minutes.

They should also do an activity which moves each foot and leg.

• A computer user should be seated at least two feet away from the

screen with the screen below eye level. Their chair should be

comfortable and they should sit up straight in the chair with feet firmly on the floor. They should not cross their legs.

7. Posture-related injuries Back and neck pain, headaches, and shoulder and arm pain are common computer-related

injuries. Such muscle and joint problems can be caused or made worse by poor workstation

design, bad posture and sitting for extended periods of time.

Although sitting requires less muscular effort, it still causes fatigue and requires parts of the body to

be held steady for long periods of time. This reduces circulation to the muscles, bones, tendons

and ligaments and can result in stiffness and pain. If a workstation is not set up properly, these

steady positions can put even greater stress on muscles and joints.



Prevention tips – muscle and joint injuries Suggestions to reduce the risk of muscle and joint problems include:

• Use an adjustable desk designed for use with computers; position the monitor so that it is

either at eye level or slightly lower.

• Position your keyboard at a height that allows your elbows to rest comfortably at your side. Forearms should be roughly parallel with the floor and level with your keyboard.

• Adjust your chair so that your feet rest flat on the floor.

• Use a footstool (if your feet do not rest on the floor when the chair is adjusted for good arm position).

• Switch to an ergonomic chair, which helps your spine to naturally hold its curve while

sitting.

• Use an ergonomic keyboard to offer your hands and wrists a more natural holding position.

• Take frequent short breaks and go for a walk or perform stretching exercises at your desk. Stand often.

8. Overuse injuries of the upper limbs Muscles and tendons can become painful with repetitive movements and awkward postures. This

is known as ‘overuse injury’ and these typically occur in the elbow, wrist or hand of computer users.

Symptoms of overuse injuries in the upper limbs include pain, swelling, stiffness of the joints,

weakness and numbness.

Prevention tips – overuse injuries Suggestions to reduce the risk of overuse injuries include:

• Keep your mouse at the same height as your correctly positioned keyboard.

• Position the mouse as close as possible to the side of the keyboard.

• Use your whole arm, not just your wrist, when using the mouse.

• Type lightly and gently.

• Mix your tasks to avoid long, uninterrupted stretches of typing.

• Remove the hands from the keyboard when not actively typing, to allow the arms to relax.

9. Eyestrain Focusing your eyes at the same distance point for extended periods of time causes fatigue. The human eye structurally prefers to look at objects further than six metres away, so any work

performed close-up puts extra demands on the eye muscles.

The illuminated computer screen can also contribute to eye fatigue. While there is no evidence

that eye fatigue is associated with damage to the eyesight, computer users may experience

symptoms such as blurred vision, temporary inability to focus on faraway objects and headaches.

Prevention tips – eyestrain Suggestions to reduce the risk of eyestrain include:

• Make sure your primary light source (such as a window) is not shining into your face or directly onto the monitor.

• Tilt the monitor slightly to eliminate reflections or glare.

• Make sure your computer screen is not too close to your face.

• Position the screen so that it is either at eye level or slightly lower.

• Reduce the contrast and brightness of your screen by adjusting the controls on the

monitor.

• Frequently look away from the screen and focus on faraway objects.

• Have regular eye examinations to check that blurring, headaches and other associated problems are not caused by any underlying disorders.

Pain in the buttocks Pain in the buttocks radiating down the thigh can be caused by a chair seat that is too long and

causing pressure behind the knees or from inadequate lumbar support.

Pain in the shoulders � Pain in the shoulders can be caused by having arms on the chair that cannot be adjusted

this causes the user to sit with the arms sticking out.



� Sitting at the desk with one elbow supported on the desk and the other held lower or

twisting the torso to look at the monitor will also cause pain.

Pain in the knees � Pain in the knees can be caused by the fact that when the chair has been adjusted to the

correct height to allow the fingers to be horizontal to the keys, the feet are left

unsupported, the solution is to purchase a footrest the small step type called (twin plus in

the Lyreco catalogue are best because they do not take up much space under the desk,

they can be adjusted according to the height of the person using them.)

If transcription is carried out it is better to have a large surface area on the footrest and the

ability to keep this level to support the footswitch.

� Pain in the knees can also be caused by a seat that is too long resulting in pressure behind

the knees.

Eye strain � Eyestrain can be caused by glare from the monitor or from overhead lights. Ideally the

desk should be placed between lights and not directly under them. If this is not possible

you may be able to switch the overhead light off and use an angle poise lamp.

� Glare from windows without blinds or with incorrectly fitted blinds. � Where there are casement window at the top and blinds cannot be used there is often

glare from the sun on the screen. Some vertical blinds are not efficient and additional

blackout roller blinds would improve efficiency and keep the room cool. If blinds cannot be fitted it may be possible to fit a tinted transparent film to the window.

Other solutions: � See the Optician about middle distance correction

� Ask about a slight tinted coating to your glasses

� Contact IT if there is any flicker on your screen

� If your monitor is old and small (14inch CGA, VGA) it will have poor resolution and should

be replaced with a 17inch SVGA or XGA.

� Clean your screen

� Adjust your contrast or brightness

� Make sure that you are not too far away from the screen (correct viewing distance is 18-20

inches)

WORD PROCESSING TERMINOLOGY Spelling checker

• A companion application that you use with a word-processing application to check for misspelled words.

• A word processing function which searches for and corrects misspellings by comparing a document's words with those in a built-in spelling dictionary.

• spell-checker: an electronic dictionary in a word processor that can be used to catch

misspelled words

• In computing terms, a spell checker or spelling checker is a design feature or a software program designed to verify the spelling of words in a document, helping a user to ensure

correct spelling. A spell checker may be implemented as a stand-alone application

capable of operating on an block of text; however, spelling checkers are more often

implemented as a feature of a larger document-related application, such as a word

processor or an email client.

Macros • In the context of programming by demonstration, this usually refers to any procedure

created by recording the user's actions as they are carried out. Unlike the conventional

computer-science definition, the use here does not necessarily have any implications

about how the procedure is executed (whether it is expanded in-line using textual

substitution or called as a function).

• A macro in computer science is an abstraction, whereby a certain textual pattern is replaced according to a defined set of rules. The interpreter or compiler automatically

replaces the pattern when it is encountered. In compiled languages, macro-expansion

always happens at compile-time. The tool which performs the expansion is sometimes

called a macro-expander. ...



Header Text that appears at the top of every page of a document when it is printed.

Footer • Located at the bottom of the page, it usually contains information about the page author

or the sponsor. You may also find copyright information and the date the page was last

updated.

• Text that appears at the bottom of every page in a document.

Mail merge • The process by which information (e.g. names and addresses) from a database or other list

and inserted into a standard document or letter to produce multiple personalized copies.

• A mass-mail facility that takes names, addresses, and (sometimes) pertinent facts about recipients and merges the information into a form letter or another such basic document.

• The transfer of data from one computer file to address and/or personalize mailing items in

another. JUSTIFICATION

HARD RETURN

SPREADSHEET TERMINOLOGY Microsoft Excel is a spreadsheet program written and distributed by Microsoft for computers using

the Microsoft Windows operating system and for Apple Macintosh computers. It features an

intuitive interface and capable calculation and graphing tools which, along with aggressive

marketing, have made Excel one of the most popular microcomputer applications to date. ...

Workbook

• A spreadsheet document that contains one or more worksheets, a Microsoft Excel document.

• A collection of related worksheets contained within a single file. (in spreadsheet

applications).

• The workbook is the main document used in software programs like Excel. A workbook

consists of individual worksheets, like an accountant's workbook, each of which can

contain data. Basically, a workbook is a very sophisticated ledger.

Worksheet • A single spreadsheet that contains rows and columns of data. In Excel, a worksheet will

have a little white tab at the bottom of the screen. A worksheet is treated like a database

table.

• An electronic spreadsheet containing 256 columns by 16,384 rows. (in spreadsheet applications).

• A work area comprised of rows and columns, also known as a spreadsheet. x-axis label

• A label describing the x-axis of a chart. (in spreadsheet applications

Cell An intersection of a row and column, the smallest element in which you can enter data.

Column A vertical selection of cells identified by one or more letters, starting with A at the left side

of the spreadsheet.

Row A horizontal selection of cells identified by a number, starting with 1 at the top of

thespreadsheet.

Formula An equation that performs an operation on cell data and displays the result. For example,

to add the contents of cells A1 and A2, and display the results in A3, cell A3 would contain

=A1+A2, a simple formula.

Function A pre-defined formula that allows you to quickly perform a more difficult operation on cell

data, such as finding the average of a range of numbers. Functions always take

arguments, or additional information that enables the computation to occur. For

example, the argument to the AVG, or average, function is the range of cells to be

averaged: =AVG(A1..C10) averages all cells between A1 (in the upper left) and C10 (in



the lower right).

Cell reference • The column number and the row letter of a cell.

• The address or name of a specific cell. Cell references may be used in formulas and are relative or absolute. (Spreadsheet application).

• A cell name used in a formula.

Cell pointer • A highlighted rectangle around a cell that indicates the active cell. (Spreadsheet

application)

Relative cell reference • Used to indicate a relative position in a worksheet. This allows you to copy and move

formulas from one area to another of the same dimensions. Excel, for example,

automatically changes the column and row numbers to reflect the new position. (in

spreadsheet applications).

• Cell references in formulas that change when Excel copies them to another location. Absolute cell reference on the Web:

• A cell reference in which a dollar sign ($) precedes both the column and row portions of

the cell reference. Mixed cell reference

• Cell reference in which either the column or the row is never adjusted if the formula

containing it is copied to another location.

Cell address • Usually the intersection of a cell's row and column.

• Unique location identified by intersecting column and row coordinates. (Spreadsheet application)

What if analysis • The process of playing with numbers to see how they interact in a spreadsheet.

Freeze panes • Freezing panes prevents the data in the panes from scrolling as you move to different

areas in the worksheet.

Goal seek on the Web:

• Goal Seek is a tool that is used to find the value needed in one cell to attain a result you want in another cell.

Formula • A set of instructions that you enter in a cell to perform numeric calculations

(adding, multiplying, averaging, etc.); for example, +A1+B1. (in spreadsheet

applications)

• Instructs the spreadsheet to perform a calculation using the contents of a specific

cell or range of cells

Filter • A program that processes individual, personal preferences in an attempt to deliver

relevant information to a particular end user. Solver

• Solver is a tool used to perform what-if analyses to determine the effect of changing

values in tow or more cells on another cell.

Recalculation • The act of calculating again (usually to eliminate errors or to include additional data);

"recalculation yielded a much larger value"

Absolute cell reference: A cell address in a formula that does not change when copied to

another cell. An absolute reference has the form $A$1.

Active cell: The selected cell in a worksheet. The active cell is surrounded by a

heavy border and is identified by the cell address.



Argument:

The information that a function uses to produce a new value or

perform an action. For example, a new value is displayed when the

SUM function adds the argument (A6:A12). An argument consists of

numbers, references, text, operators, or error values.

Ascending: A method of ordering a group of items from lowest to highest, such

as from A to Z.

AutoFilter: Displays all records that meet the criteria as a subset of the

database.

AutoFormat: A feature used to format a range of cells with a predefined set of

attributes.

AVERAGE function: Sums the numbers in the specified range and then divides the sum

by the number of non-zero cells in the range.

Cell reference: An unique address given to a cell; the coordinates of the

intersection of a column and a row.

Cell: Basic unit of a worksheet into which you enter data.

Chart:

A graphic representation of worksheet data. Values from

worksheet cells are displayed as bars, lines, or other shapes.

Common chart types are pie, bar, line, and area.

Column heading: The lettered gray area at the top of each column that identifies the

letter of the column, such as column B.

Comment: A note that explains, identifies, or comments on the information in a

specific cell or range of cells.

Condition: Made up of two values and a relational operator, is true or false for

each cell in the range.

Conditional formatting: Allows you to apply formatting that appears only when the value in

a cell meets conditions that you specify.

Criteria:

The conditions that control which records to display in a query; the

words or values used to determine the data that appears in a data

list.

Currency style format:

Displays a dollar sign to the left of the number, inserts a comma

every three positions to the left of the decimal point, and displays

numbers to the nearest cent (hundredths place).

Data table: Range of cells that shows the answers generated by formulas in

which different values have been substituted.

Data validation: Restricts the values that may be entered into a cell by the

worksheet user.

Debugging: Process of finding and correcting errors in the worksheet.



Descending: A method of ordering a group of items from highest to lowest, such

as from Z to A.

Dummy data: Used in place of actual data to verify formulas in the template.

Embedded chart: A chart that exists on a worksheet instead of on a separate chart

sheet.

Exploded Pie chart: A Pie chart with one or more slices offset.

Filter:

A set of criteria you can apply to records to show specific tasks,

records, or resources. The tasks, records, or resources that match

your criteria are listed or highlighted so that you can focus on just

the information you want.

Formula:

A sequence of values, cell references, names, functions, or

operators that produces a new value from existing values. A

formula always begins with an equal sign (=).

Function: A built-in formula; a named and stored procedure that performs a

specific operation and returns a value.

Goal seeking: Used if you know the result you want a formula to produce by

determining the value of a cell on which the formula depends.

Gridlines: The horizontal and vertical lines on the worksheet.

IF function:

A function that tests the content of the cell, performs a calculation,

and displays a value or text based on whether the test is true or

false.

Label: Row title or column title.

Legend: A box containing the name of each data series in a chart.

MAX function: Displays the highest value in a range.

MIN function: Displays the lowest value in a range.

NOW function: Used to enter the system date in a cell in the worksheet.

PivotChart:

An interactive chart that provides the user with ways to graphically

analyze data by varying the fields and categories to present

different views.

PivotTable:

An interactive worksheet table that summarizes data using a

selected format and calculations. It is called a pivot table because

you can rearrange the table structure around the data.



Protected cells: Cells that you cannot change.

Range: Series of two or more adjacent cells in a column or row or a

rectangular group of cells.

Reference: A cell address used in a formula.

Relative cell reference: In formulas, a reference to the address of another cell in relation to

a cell that contains a formula.

Template: Special workbook or worksheet you can create and then use as a

pattern to create new, similar workbooks or worksheets.

Unprotected cells: Cells whose values you can change at any time.

Worksheet:

A set of rows, columns, and cells in which you store and manipulate

data. Several worksheets can appear in one workbook, and you

can switch among them easily by clicking their tabs with the

mouse.

X-axis: A line, usually horizontal, along the bottom of a chart. The x-axis

shows the labels for the data series. Also called the horizontal axis.

Y-axis: A line, usually vertical, along the left side of a chart. The y-axis

shows the values for the data series.

Part A

i. Worksheet an electronic spreadsheet containing 256 columns by 16 384 rows. A single

spreadsheet that contains rows and columns of data . A set of rows, columns and cells in

which you store and manipulate data

ii. Cell address usually the intersection of a row and a column. Is the location of a cell on a

worksheet and is defined by the column letter and the row number. E.g. cell A1 is where

column A and Row 1 intersect.

iii. Formula a set of instruction that you enter in a cell to perform numeric calculations =

A1+B1

iv. Cell Pointer (cursor) A highlighted rectangle around a cell that indicates the active cell. v. Cell an intersection of a row and column, the smallest element in which you can enter

data.

Part B

i. Footer text that appears at the bottom of every page in a document ii. Text that appears at the top of every page of a document when it is printed.

iii. Spell Checker F1 word processing function which searches for and correct misspellings

by comparing a document’s words with those in built-in spelling dictionary.

iv. Font is a style and size of type e.g Times New Roman, 12 point is a set of all the

characters available in one typeface and size, including uppercase and lowercase

letters, punctuation, and numerals.

v. Alignment the position of lines in a paragraph in relation to the document’s left and right

margins i.e. whether they are left-aligned, centered, right-aligned or justified.


a) State the functions of the Control Unit & Arithmetic Logic Unit. [5].

Control unit functions

Manages input-output to & from the main

memory

Interprets instructions in sequence

Issue commands to all elements of the

computer

Directs sequence of

Directs traffic in the computer [make

decisions]

Interprets coded instructions

Initiates proper commands to other parts

of the computer.

Performs the functions of fetch, decode,

execute, and store.

Three types of Data Transmission:

1. SIMPLEX Data in a Simplex transmission is always one way. Simplex transmission are not often used because it is

not possible to send back error or control

It's like a one-way street. An example of simplex is

2. HALF DUPLEX A half-duplex transmission can send and receive in one direction, but not at the same time. It's like a

one-lane bridge where two-way traffic must give way in order to cross. Only one end transmits at a

time, the other end receives. In addition, it is possible to perform error detection and request the

sender to retransmit information that arrived corrupted. In some aspects, you

surfing as being half-duplex, as a user issues a request for a web document, then that document is

downloaded and displayed before the user issues another request.

Another example of half-duplex is talkback radio, and CB Radio (Citiz

movies where a truck driver (drivers of very big trucks) communicates to each other, and when they

want the other person to speak they say "over". This is because only one person can talk at a time



State the functions of the Control Unit & Arithmetic Logic Unit. [5].

Control unit functions A.L.U functions

output to & from the main Performs arithmetic operations

Interprets instructions in sequence Performs logical operations

Issue commands to all elements of the Performs computations on data.

Directs sequence of operations Is where binary data is acted upon?

Directs traffic in the computer [make Stores intermediate and final results of

arithmetic operations

Interprets coded instructions

Initiates proper commands to other parts

of the computer.

forms the functions of fetch, decode,

execute, and store.

Data in a Simplex transmission is always one way. Simplex transmission are not often used because it is

not possible to send back error or control signals to the transmit end.

way street. An example of simplex is television, or Radio.

duplex transmission can send and receive in one direction, but not at the same time. It's like a

way traffic must give way in order to cross. Only one end transmits at a


sender to retransmit information that arrived corrupted. In some aspects, you can think of Internet

duplex, as a user issues a request for a web document, then that document is

downloaded and displayed before the user issues another request.

duplex is talkback radio, and CB Radio (Citizens Band). You might have seen




130

Performs arithmetic operations

Performs logical operations

Performs computations on data.

Is where binary data is acted upon?

Stores intermediate and final results of

Data in a Simplex transmission is always one way. Simplex transmission are not often used because it is

duplex transmission can send and receive in one direction, but not at the same time. It's like a

way traffic must give way in order to cross. Only one end transmits at a


can think of Internet

duplex, as a user issues a request for a web document, then that document is

ens Band). You might have seen




3. FULL DUPLEX

Data can travel in both directions simultaneously. There is no need to switch from transmit to receive

mode like in half duplex. It like a two lane bridge on a two

these television talk shows where the host has a number of peopl

at once. Well, that's full duplex!

Of course, in the world of data communications, full duplex allows both way communications

simultaneously. An example can be a consumer, which uses a cable connection not only, rece

channels, but also the same cable to support their phone and Internet surfing. All these activities can

occur simultaneously.

Practical QUESTION

a. Name any 2 word processing packages

b. What is page break in word processing and why is it used

c. How do you save a file on a floppy disk using the word processor you have

d. How do you underline a block of previously typed text using the word processor you have

studied?

e. Explain the difference between

i. SAVE & SAVE AS



travel in both directions simultaneously. There is no need to switch from transmit to receive

mode like in half duplex. It like a two lane bridge on a two-lane highway. Have you ever watched

these television talk shows where the host has a number of people on the show, and they all try to talk


simultaneously. An example can be a consumer, which uses a cable connection not only, rece


2 word processing packages.

What is page break in word processing and why is it used/

How do you save a file on a floppy disk using the word processor you have studied?

How do you underline a block of previously typed text using the word processor you have

Explain the difference between

SAVE & SAVE AS


131

travel in both directions simultaneously. There is no need to switch from transmit to receive

lane highway. Have you ever watched

e on the show, and they all try to talk


simultaneously. An example can be a consumer, which uses a cable connection not only, receives TV


studied?

How do you underline a block of previously typed text using the word processor you have



ii. COPY & CUT iii. DELETE & BACK SPACE iv. PORTRAIT & LANDSCAPE v. TOGGLE CASE & UPPERCASE

f. Briefly outline the procedures for performing the following functions in a windows environment. i. Creating a folder

ii. Opening a folder

iii. Searching folders or files

iv. Renaming a file or folder

v. Creating a shortcut for a file or

folder

vi. Copy file from one folder to another

vii. Move a file from one folder to

another

viii. Deleting a file or folder

ix. Arrange icons on the desktop

x. Change screen saver

xi. Click

xii. Right click

xiii. Double click

xiv. Drag

xv. Loading windows

xvi. Shutting down a computer

xvii. Emptying recycle bin

xviii.

g. Briefly outline the procedures for performing the following functions using a spreadsheet of your choice

i. Expanding a cell ii. Adding a list of figures in the range A10 to D10 iii. Insert a full border around a document iv. Adding and Renaming Worksheets v. Resizing Rows and Columns



h.Briefly outline the procedures for performing the following functions using a word processor of your choice

1. Opening a Microsoft

word program for

typing 2. Saving a document

3. Retrieving a document

4. Setting landscape or

portrait orientation

5. Print preview

6. Formatting text into

italics

7. Setting left and right

margins

8. Inserting a header or a

footer

9. Open a document

which has been saved

before

10. Insert a picture 11. Insert a table 12. Printing a word

document

13. Exit MS Word

14. Save a document 15. Copy a document or a

word

16. Double line spacing 17. Insert a header 18. Insert page number

19. Save a document onto

a floppy disk

20. Mail merge

21. JUSTIFYING TEXT 22. Inserting bullets 23. Indenting text 24. Moving a block of text

25. Copying a block of text 26. Creating a table 27. Adding rows to a table 28. Adding columns to a

table

29. Deleting rows of a table

30. Deleting columns of a table

31. Shading a table 32. Merging cells of a table

33. Splitting cells 34. Changing text

direction

35. Inserting drop caps 36. Having 2 columns on a

word document

37. Bordering and shading a paragraph

38. Change case of a word

39. Locking a word file with a password

Question 26 (a) Discuss any 4 possible uses of spreadsheets in a business organization. [8 marks]

(b) Explain the following terms as used in spreadsheets

I. Cell

II. Range. [2 marks each] (c) Explain the following terms as used in a word processing

I. Soft return

II. Hard return

III. Thesaurus

IV. Widow

V. Orphan. [2 marks each]

Question 24 (a) Define an electronic spreadsheet. [3 marks]

(b) List 5 facilities provided by a spreadsheet. [5 marks]

(c) What is word processing? [2 marks]

(d) Explain the following word processing terms

I. Justification

II. Hard return

III. Soft return

IV. Header

V. Orientation. [2 marks each]

Question 15 Briefly explain the following terms as used in a spreadsheet

(a) Active cell (b) Cell (c) Legend (d) What if analysis (e) Label (f) FUNCTION

(g) GRAPH (h) Formula

(i) Cell address

(j) Worksheet

(k) Cell reference (l) Relative cell reference

(m) Cell pointer (n) Absolute cell reference (o) Mixed cell reference

(p) Work book

(q) Goal seek (r) Range

(s) Protected cells

(t) Freeze panes



(u) Embedded chart (v) Row & column

[1 mark each]

Question 16 Briefly explain the following terms as used in a Word processing

(a) Orphan (b) Header (c) Footer (d) TEMPLATE

(e) Spellchecker (f) FONT

(g) TAB STOPS (h) Mail merge

(i) Font type

(j) Justification

(k) Word wrap

(l) Bold

(m) Borders (n) Bullets (o) Hard return (p) STATUS BAR (q) Indentation (r) Soft return

(s) Widow/Orphan Control

(t) Widow

(u) Thesaurus (v) Format bar

(w) Standard bar (x) Center alignment

[1 mark each]

Question 6

(a) Define a word processor & give an example [2 marks]

(b) List down at least 5 facilities provided by a word processor [5 marks]

(c) Give a suitable term/ phrase that best describes the following statements in word

processing.

i) The automatic movement of typed text to the new line, without pressing

the enter key.

ii) Different “handwritings” in a computer.

iii) Line spacing. [1 mark each]

(d) Define a spreadsheet and give an example [2 marks]

(e) Give the difference between a spreadsheet & a worksheet [2 marks]

(f) Give a suitable word/ phrase that best describes the following spreadsheet terms

I. Cell [2 marks]

II. Hard copy [2 marks]

III. Creating a permanent copy of a worksheet on a computer. [2 marks]

QUESTION 31

(a) Define the term Operating System. [3 marks]

(b) State any 4 functions of an operating system. [4 marks]

(c) State any 3 examples of an Operating system (exclude the Windows family).

[3 marks]

(d) Define the following Windows Operating Systems based terms:

I. Desktop

II. Icon

III. Taskbar

IV. Window

V. Cascade window [2marks each]

Question 6 Expand the following abbreviations.

a) GIGO

b) WYSIWYG c) LED

d) LCD

e) MS DOS

f) OCR

g) MICR

h) CD ROM

i) ASCII

j) COM k) WIMP

l) GUI

m) WIMP

n) CRT

o) DBMS

p) POP 3

q) HTML

r) URL s) TCP-IP

t) CAD

u) RAM

v) ROM

w) DSS x) LAN

y) 4GL

z) UPS aa) PABX bb) DRAM

cc) SRAM

dd) EFT ee) WAN

ff) PC



gg) MIS

hh) EBCDIC ii) MHz

jj) OMR

kk) SDLC ll) HTTP

mm) C

PU

nn) DBA oo) EPROM

pp) VDU qq) ALU rr) DOS

ss) FORTRAN

tt) COBOL

uu) ISP vv) CPU ww) W

WW

xx) DVD

yy) VOIP zz) ISDN aaa) U

RL

bbb) P

ROM[20

marks]

Question 7 Explain the following terms in detail, giving examples where applicable.

a) Computer peripherals

b) Program

c) BLUETOOTH

d) Computer

e) Hardware

f) Software

g) Operating system

h) Application software

i) Utility software

j) Machine language. k) Random access memory. [20 marks]

Question 8 Explain the following terms as used in word processing or spreadsheet

a) Menu

b) Footer

c) Soft return

d) Edit

e) Cell

f) Label

g) Chart

h) Mail merge

i) Print preview

j) Work sheet. [2 marks each]

Questions (a) Discuss any 4 possible uses of spreadsheets in a business organization. [8 marks]

(b) Explain the following terms as used in spreadsheets

I. Cell o The intersection of a row and a column on a spreadsheet in which data can

be entered.

II. Range. o Series of two or more adjacent cells in a column or row or a rectangular group

of cells.

III. [2 marks each]

(c) Explain the following terms as used in a word processing

VI. Soft return o A soft return is entered automatically by a word processor's word wrap feature

when the text reaches the end of the line. It is contrasted with a hard return

which is used primarily to begin a new paragraph. A little known feature of

Microsoft Word and OpenOffice. ...

VII. Hard return o Made by pressing the return or enter key on the keyboard. A hard return, or

carriage return, creates a line break and identifies the end of a paragraph.

VIII. Thesaurus


136

o Provides a listing of words and their synonym/related words.

o Guide to use of terms, showing relationships between them, for the purpose of

providing standardized, controlled vocabulary for information storage and

retrieval

IX. Widow o In typesetting, a widow occurs when the majority of a paragraph appears on

one page with the last line of that paragraph flowing to the top of the

following page. ...

o The last line of a paragraph at the top of a page of text.

X. Orphan. o In typesetting, an orphan is the first line of a paragraph appearing on its own

at the bottom of a page with the remaining portion of the paragraph

appearing on the following page. The first line of the paragraph was "left

behind" by the remaining portion of text. ...

o Line of type on its own at the bottom of a page.

[2 marks each]

Question 24 (a) Define an electronic spreadsheet. [3 marks]

(b) List 5 facilities provided by a spreadsheet. [5 marks]

(c) What is word processing? [2 marks]

(d) Explain the following word processing terms

VI. Justification a. In typesetting, justification (can also be referred to as 'full justification') is the

typographic alignment setting of text or images within a column or "measure" to

align along both the left and right margin. Text set this way is said to be "justified".

b. The alignment of text in a paragraph so that the margins are all straight on the

right side, or the left side, or both. E.g. this text is left justified.

VII. Hard return

VIII. Soft return

IX. Header o Text that appears at the top of every page of a document when it is printed.

X. Orientation. o Whether page is vertically or horizontally aligned. For example we have portrait and

landscape orientation.

o Portrait orientation. The mode in which content is viewed where the width is shorter than

the height. Portrait orientation mimics the way most reading material is printed, eg, letters,

newspapers, books. ...

o Landscape orientation. The mode in which content is viewed where the width is longer

than the height. Landscape is the traditional orientation for computer viewing and is

appropriate when viewing spreadsheets, video games, and movies.

[2 marks each]

Question 15 Briefly explain the following terms as used in a spreadsheet (a) Active cell (b) Cell (c) Legend (d) What if analysis

(e) Label (f) FUNCTION

(g) GRAPH (h) Formula

(i) Cell address

(j) Worksheet

(k) Cell reference

(l) Relative cell reference

(m) Cell pointer (n) Absolute cell reference (o) Mixed cell reference

(p) Work book

(q) Goal seek (r) Range

(s) Protected cells

(t) Freeze panes

(u) Embedded chart

(v) Row & column [1 mark each]


137

Question 16 Briefly explain the following terms as used in a Word processing

(a) Orphan (b) Header (c) Footer (d) TEMPLATE

(e) Spellchecker (f) FONT

(g) TAB STOPS (h) Mail merge

(i) Font type (j) Justification

(k) Word wrap

(l) Bold

(m) Borders (n) Bullets

(o) Hard return (p) STATUS BAR (q) Indentation (r) Soft return

(s) Widow/Orphan Control

(t) Widow

(u) Thesaurus (v) Format bar

(w) Standard bar (x) Center alignment

(y) Hyphenation – is used to eliminate gaps

in justified text or to maintain even line

lengths in narrow columns. You can

hyphenate manually or automatically.

[1 mark each]

Question 6

(g) Define a word processor & give an example [2 marks]

(h) List down at least 5 facilities provided by a word processor [5 marks]

(i) Give a suitable term/ phrase that best describes the following statements in word

processing.

i) The automatic movement of typed text to the new line, without pressing

the enter key.

ii) Different “handwritings” in a computer.

iii) Line spacing. [1 mark each]

(j) Define a spreadsheet and give an example [2 marks]

(k) Give the difference between a spreadsheet & a worksheet [2 marks]

(l) Give a suitable word/ phrase that best describes the following spreadsheet terms

IV. Cell [2 marks]

V. Hard copy [2 marks] VI. Creating a permanent copy of a worksheet on a computer. [2 marks]

QUESTION 31

(e) Define the term Operating System. [3 marks]

(f) State any 4 functions of an operating system. [4 marks]

(g) State any 3 examples of an Operating system (exclude the Windows family).

[3 marks]

(h) Define the following Windows Operating Systems based terms:

I. Desktop o The main workspace in a graphical user interface such as Windows or

Macintosh Systems. Users open and work with files and programs on the

desktop, and can store files and shortcuts there as well. The user can also

customize the look of the desktop with images or wallpaper and custom icons.

o Is the background screen on the computer? It consists of pictures, called icons

that show cabinets, files, folders, and various types of documents.

II. Icon o A picture or graphical representation of an object on a display screen to

which a user can point to with a device, such as a mouse, to select a

particular operation or perform a certain action.

III. Taskbar o The bar usually found at the bottom of a Windows screen. The taskbar shows

which software programs are open. It also contains the Start button.

o A windows 95/98 screen elements, displayed on the desktops which includes


138

the start button and lists the programs currently running on the computer.

IV. FOLDER o Folder, a virtual container within a digital file system, in which groups of files and

other folders can be kept and organized.

V. WIMP o WIMP (Windows Interface Manipulation Program, also refers to Windows, Icons,

Menus and Pointing device - the prehistorical GUI of the 1970's) is a program for

creating full-screen visual animations synchronized with sound in real time. As

the only visual input WIMP utilizes graphical user interface (GUI) of Windows

operation system. Whatever applications windows, icons, images, texts, etc. you

have open on your desktop - they become an inspiration source for WIMP and

you. Animations are generated by simple 2- and 3-D effects and filters and their superimpositions. As such WIMP can be used as a VJ tool, a screensaver, a cool

grafix generator or as a piece of conceptual art. VI. RECYCLE BIN

o In the Microsoft Windowsoperating systems, the Recycle Bin is a holding area for files and folders that are held before final deletion from a storage device.

VII. GUI o A graphical user interface (GUI) is a type of user interface item that allows people

to interact with programs in more ways than typing such as computers; hand-held

devices such as MP3 Players, Portable Media Players or Gaming devices;

household appliances and office equipment with images rather than text

commands. A GUI offers graphical icons, and visual indicators, as opposed to text-

based interfaces, typed command labels or text navigation to fully represent the

information and actions available to a user. The actions are usually performed

through direct manipulation of the graphical elements.[1]

VIII. Window o In computing, a window is a visual area, usually rectangular in shape,

containing some kind of user interface, displaying the output of and allowing

input for one of a number of simultaneously running computer processes. ...

IX. Cascade window o An arrangement of Windows so each window is neatly stacked with only the

title bar of each window is showing.

o Arrange (open windows) on a computer desktop so that they overlap each other, with the title bars visible

[2marks each]

Question 7 Explain the following terms in detail, giving examples where applicable.

a) Computer peripherals

b) Program

c) BLUETOOTH a. Bluetooth® is the codename for a technology specification for low-cost, short-

range radio links between mobile PCs, mobile phones and other portable devices,

and connectivity to the Internet. ...

b. Bluetooth is the name given to a radio technology making transmission of signals

over short distances between telephones, computers and other devices, like

household appliances, without the use of wires.

d) Computer

e) Hardware

f) Software

g) Operating system

h) Application software

i) Utility software

j) Machine language.

k) Random access memory. [20 marks]

Question 8


139

Explain the following terms as used in word processing or spreadsheet

k) Menu a. A list of options, each of which performs a desired action such as choosing a

command or applying a particular format to a part of a document. Menus are

commonly used in graphical interfaces.

l) Footer

m) Soft return n) Edit

o To review a piece of writing, marking and correcting grammatical, spelling, and

factual errors. The editing process also often includes shortening or lengthening articles

to fit available space, writing headlines and subheads. o) Cell

p) Label

q) Chart

r) Mail merge

s) Print preview

t) Work sheet. [2 marks each]



ABBREVIATIONS

1) ALU Arithmetic Logic Unit

2) ARC net Attached Resource Computer Network

3) ASCII American Standard Code for Information Interchange

4) B2B Business-To-Business

5) BCD Binary Coded Decimal

6) BIOS Basic Input/Output System

7) BIS Business Information System

8) BIT Binary Digit 9) BLOG Web Log

10) BSYNC Binary Synchronous Communications (protocol) 11) C C Programming Language

12) CAD Computer Aided Design

13) CAL Computer Aided Learning

14) CASE Computer Aided Software Engineering

15) CDMA Code Division Multiple Access

16) CD-R Compact Disk - Recordable

17) CD-ROM Compact Disk - Read Only Memory

18) CD-RW Compact Disk - Rewritable

19) COBOL Common Business-oriented Language (See HLL)

20) CODEC Coder/Decoder + Compression/Decompression

21) COE Common Operating Environment

22) CPU Central Processing Unit 23) CRC Cyclic Redundancy Check 24) CRT Cathode Ray Tube 25) CSMA/CA Carrier Sense Multiple Access/with Collision Avoidance

26) CSMA/CD Carrier Sense Multiple Access/with Collision Detection

27) CSMS Customer Support Management System

28) DSS Decision Support System

29) DTE Data Terminal Equipment + Dumb Terminal Emulator

30) DVD Digital Video Disk 31) DVD-A Digital Video Disk-Audio

32) DVD-AR Digital Video Disk-Audio Recording 33) DVD-R Digital Video Disk-Recordable 34) DVD-RAM Digital Versatile Disc-RAM

35) DVD-ROM Digital Versatile Disc-ROM

36) DVD-SR Digital Video Disk-Stream Recording

37) DVD-VR Digital Video Disk-Video Recording

38) DVR Digital Video/Voice Recorder 39) EBCDIC Extended Binary Coded Decimal Interchange Code [IBM]

40) EEPROM Electrically Erasable Programmable Read-Only Memory

41) EFTS Electronic Funds Transfer System

42) E-MAIL Electronic Mail

43) EPROM Electrically Programmable Read Only Memory +

i. Erasable Programmable Read Only Memory

44) FTP File Transfer Protocol [Internet] 45) FDDI Fiber Digital Device Interface +

i. Fiber Distributed Data Interface

46) FDISK Fixed Disk 47) FDM Frequency Division Multiplexing

48) FDMA Frequency Division Multiple Access

49) FDX Full Duplex 50) FEC Forward Error Correction 51) FM Frequency Modulation

52) FORTRAN Formula Translator (Programming Language)(See HLL)

53) FTP File Transfer Protocol 54) GHZ Gigahertz



55) GIGO Garbage In, Garbage Out

56) GIS Geographic Information System

57) GSM Global System for Mobile-Communications (network)

58) GUI Graphical User Interface 59) HDD Hard Disk Drive

60) HDLC High-Level Data Link Control 61) HLL HIGH LEVEL LANGUAGE 62) HDTV High Definition Television 63) HTML HyperText Markup Language

64) HTTP HyperText Transfer Protocol 65) Hz Hertz 66) IP Internet Protocol 67) IQL Interactive Query Language

68) ISDN Integrated Services Digital Network 69) IT Information Technology

70) LAN Local Area Network 71) LCD Liquid Crystal Display 72) LED Light Emitting Diode

73) LPT Line Printer Terminal

74) LPT1FirstParallelPrinterPort 75) LPT2SecondParallelPrinterPort 76) LPT3 ThirdParallelPrinterPort 77) MBps Megabytes Per Second

78) Mbps Megabits Per Second

79) MBR Master Boot Record

80) MHz Megahertz

81) MICR Magnetic Ink Character Recognition

82) MIDI Musical Instrument Digital Interface

83) MIS Management Information System

84) MODEM Modulator/Demodulator

85) MP3 MPEG Audio Layer 3

86) MSAV Microsoft Anti Virus [Microsoft]

87) MS-DOS Microsoft - Disk Operating System [Microsoft]

88) PDF Package Definition File + Portable Document Format + i. Portable Document File + Processor Defined Function +

ii. Program Development Facility

89) .PDF Printer Description (file name extension)[Borland, Lotus]

90) P2P Peer To Peer + People To People

91) USB Universal Serial Bus 92) WYSBYGI What You See Before You Get It

93) WYSIWYG What You See Is What You Get



Basic Computer Terminology

Computer has turned from being just a technological gadget to personal PC to a super

technological personal gadget. There is nothing in the world that does not depend on computers.

You need to understand the basic computer terms and meanings in order to stay up-to-date with

the world. If you do not know the basic computer terms and definition, you look like a lost soul in

the most happening world of technology. You need to book a movie ticket, so you need Internet

access. You have to submit a presentation for your company's project, you need a computer to

bail you out. Its out of date to use a video cassette for your recordings. Cassettes are like an

ancient relic, its CD's and DVDs that are in vogue today. And to top it all, USB flash drives have

created a niche in the minds of tech-savvy people. So before you float your mind in the floating

point numbers or scratch your head when learning the queries in databases, let us begin with some

simple basic computer terms for beginners.

Basic Computer Terms and Definitions

Computer A computer is a computing device that is similar to an automated abacus that can execute a

program, that is, a sequence of automatic instructions.

Program

A program is a is an executable software that runs on a computer. It contains compiled codes that

run directly from the computer's operating system.

Operating System

The operating system (OS) is the software that communicates with the computer hardware on the

primary level. No software can be run on the computer without the operating system. It serves as a

user interface and helps allocating memory, processes tasks, accesses disks and peripheral.

Command A command is a series of step by step instructions that helps the computer perform a specific

action.

CPU The central processing unit or CPU, also known as the microprocessor or processor is the brain of

the computer. It helps execute instructions in a software program and helps retrieve instructions

form the computer's memory, comprehending and executing instructions and helping direct the

input and output of the computer.

Desktop The computer monitor or the screen of the computer against which, the operating system and

access application programs, files and documents are displayed is called the desktop.

File The file is a unit for information storage that includes word-processor, spreadsheet, pictures, music,

etc. Each file is differentiated with the help of a unique file name.

Folder The folder is a unique system that helps in organizing the files, topics, programs and projects on the

computer. The similar applications in a folder will be grouped together when an application



program is loaded. It is similar to organizing files on a shelf in your cabinet.

Hard Drive The hard drive is the region where the information is stored and helps the computer to permanently

retain and store the data.

Hardware The computer system that comprises of a computer, that is, monitor, keyboard, mouse, printer,

computer unit, scanner, etc. is known as the hardware. When the CPU is opened, the components

that make a CPU are also the hardware. You can read and learn more on computer hardware

basic information.

Hyperlink An hyperlink is a program that helps one move from one web page to another. The text is

underlined and the cursor that moves over this text document, takes the shape of a hand. This

means there is a hyperlink added to the text and you can click on it to move over to another page

or document.

Internet The Internet is a world wide network that helps connect millions of users around the world to share

and exchange data, information, opinions, etc. The Internet is not similar to World Wide Web

(WWW). The WWW is a service that is provided on the Internet for the users.

Monitor The computer monitor is defined as the computer screen or display unit. The monitor helps in

displaying the user interface and programs. It is a way for the user to interact with the computer,

using the keyboard and mouse.

Mouse Do not be baffled, a computer mouse is a hand held device that helps the user move across the

flat surface and help control the pointer on the screen. It is a very accessible device, as it helps

one move faster across the screen and perform many tasks quickly.

Keyboard The computer keyboard is the peripheral unit of the computer that helps in typing in the words and

numbers along with the symbols and thus communicate with computer. In other words, it is the

way, how you can feed in information that needs to processed into your computer. You can read

more on computer keyboard shortcuts.

RAM

Random Access Memory or RAM is the temporary storage space in the computer that helps place

information so that is can execute the program and instructions given. Once a program is closed,

the data is removed from RAM. The amount of RAM helps in determining the number of programs

that can be run.

Browser The web browser is an application that helps render the source code of World Wide Web or web

pages that can be used by the user. The information is rendered in understandable form for the

user by the browser. The Microsoft Internet Explorer is an example of the browser.

Peripherals The peripherals are the input devices that are connected to the machines. The keyboard, mouse

and printer are computer peripherals. Some peripherals are important for the working of the

machine and some are added components, without which one can work on the computer.

Networks The network is a physical or logical construction that connects different computers together and helps them communicate. The computer networking is carried out through cabling or through



wireless networking. The best example is the Internet that helps sites to connect on different

computers.

Software The instructions that are provided to the computer with step-by-step actions that help executing a

specific task is a software. A computer cannot function without a software.

These were a few basic computer terms for kids that can be helpful for a beginner to understand

the computer parts list. Computers have become a part and parcel of our daily lives, without

which we cannot function. Man has become so dependent on the computer that a minor

computer glitch can send life into a tizzy. One needs to learn using a computer, as much as he

needs to learn how to read and write. Today, people breath software and eat hardware (hypothetically speaking). You do not want to be left out in this rat race of technically sound world.

So begin by learning and teaching your kids these basic computer terms for beginners.

QUIZ

A B C D

1

You have completed the document and want

to make certain that you have not made

spelling or grammar errors.

Which button do you select?

2

Text is selected and you want to remove the

selection from the active document and place

it on the clipboard.


3

You have made a change to the active

document and want to make certain that those

changes are saved. Which button do you select?

4

A phrase will appear several times in the

document. To save time you have selected the

phrase and want to copy it.


5

The document had been checked for spelling

errors, it has been saved, and now you are

ready to print.


6

A document which has been saved into a folder

on your computer is to be opened so changes

can be made.


7

The document had been checked for spelling

and has been saved. Before sending it to the

printer you want to see how it will look.




A B C D

1

Instead of striking the underline key fifteen

times, you plan to draw a single line by

clicking and dragging.


2

You have drawn a line, and now want to

change the color of the selected line.


3

The last line you drew had an arrowhead at

the wrong end. You want to change the

arrowhead to the other end of the line.


4

You created an object in a document and

you want to tilt it at an angle.


5

You have drawn a rectangle around a

section of a flyer and want to change it to a

dashed line.


6

The heading of a flyer is just plain text and

you would rather create special effects with text.


7

You are going to draw a perfect circle on

your document by holding down the shift

key, clicking and dragging.


A B C D

1

You wish to call attention to a statement in

your document by making the text bold.


2

A flyer is to be prepared inviting parents to a

performance. You want the headline to be

centered on the page.


3

You want to make sure that your instructions

are clear and plan to place them in a



bulleted list.


4

To call attention to a block of text, you want

place a block of color behind the text to

highlight it.


5

Another way to call attention to a block of

text is to place a border around it.


6

A quoted block of text has been indented.

You wish to continue the document but you

need to undo the indent. Which button do you select?

7

You have made a birthday certificate and

you want the student's name to be

displayed in color.


COMPUTER OPERATIONS & PACKAGES - KENYA ...

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