ICT FOR SOCIAL SCIENCES

HARDWARE, SOFTWARE AND OPERATING SYSTEM

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What is a Computer?An electronic device that can perform the following tasks:

Respond predictably to input Store the set of instructions needed to process the input

Process the input according to these instructions

Store the results of processing Output information

Types of Computer Supercomputers

Special high-capacity computers used by very large organisations that need massive computing power for “number-crunching”. Users: NASA, Meteorological Office.

Mainframe Large-scale computers executing millions of instructions per second. Used to process very large volumes of data; multi-user; require special accommodation and facilities. Users: Insurance companies, banks, airlines.

Types of Computer (Cont’d) Minicomputer

A desk-sized computer. Costs less than a mainframe but is powerful enough to do many jobs which only mainframes could do in the past. Less demanding in accommodation than mainframes. Users: medium-sized organisations or departments of large companies.

Microcomputer (Personal Computer) A small computer with a central processing unit

based on a microprocessor. The least powerful but most widely used type of computer. It can be designed to be used on a desk-top or carried. Users: anyone requiring modest computing facilities.

Network ComputerA small desktop computer with a processor but minimal memory and no secondary storage. Designed as a very cheap device to be linked to the Internet or a company intranet with the network server handling more of the work. Users: failed in the market because of cheaper PCs.

Types of Computer (Cont’d)

Types of Microcomputer Desktop

A personal computer with a limited range of facilities standing permanently on a desk.Most have a cheap but heavy television-style monitor. Used in offices, universities, homes etc.

Laptop (Notebook) ComputerA portable personal computer with the facilities of a desktop personal computer but generally with lower processor speeds. They use expensive flat panel screens.

Personal Digital AssistantA small hand-held computer used as an electronic personal organiser. It can input data using a pen, recognise hand-writing, run personal organisational tools and has communications capabilities.

Hardware and Software HardwareThe physical components associated with a computer or other system. It is the equipment used for input, processing & output activities.

SoftwareThe programs which control the operation of a computer, together with the associated documentation. Divided into system and application software.

Personal Computer

monitor

system unit

disk drive keyboardprinter

(output)

(process)

(output)(input)(secondary storage) (input)

mouse

hard disk(secondary storage)

Personal ComputerPersonal Computer

Input is the process of encoding or transforming data into digital codes that the computer can process.

Input devices convert data and programs that humans can understand into a form comprehensible to the CPU.

The data may be captured on a source document or entered directly into the computer.

INPUT

Input can be classified into two broad

categories.

Transcribed input

Direct-source input

KATEGORI INPUT

Keyboard

Pointing devices

Source Data Automation

INPUT EQUIPMENT

Keyboard

Pointing Devices Mouse Joystick Roller ball Touch screen Light pen Graphics tablets

A pointing device consisting of a plastic box with a partly exposed, freely moving, ball on its underside.

The movement of the ball on a flat surface causes corresponding movement of a cursor on a screen.

MouseMouse

Track or Roller Ball An upside-down mouse Cursor moved by moving theball with fingers.

Joystick mainly used for games

Other Pointing DevicesOther Pointing Devices

A finger is the most natural pointing technology of all, so much work has gone into devices which can detect where a person is actually touching an input device.

Touch TechnologyTouch Technology

Screen is covered with a plastic layer behind which are criss-crossing beams of infrared light, when the screen is touched, beams are interrupted

Infrared LEDs

Photo Detector

s

Infrared Touch ScreenInfrared Touch Screen

Interesting commercial website www.touchscreens.com/overview.shtml

click on link Anatomy of a Touchscreen

Infrared Touch Screen (Cont’d)Infrared Touch Screen (Cont’d)

Looks like a real pen but has a light source at its tip

Used by touching pen tip on specially designed screen with grid of wires

Pen senses position and software interprets position and draws a dot on the screen

Used for computer aided design (CAD)

Electronic Light Pen and Screen

The position of a pen on an electronic notepad, screen or digitising tablet may be detected, allowing a user to either move a cursor on a screen or, in newer applications, to write normally, and the computer will recognise the words that are being written.

Graphics TabletGraphics Tablet

The tip of a pen touches a specially designed screen with a grid of wires

Software interprets the pen tip’s position and draws a dot on the screen

Small and easy to carry

Pen-based Computer SystemsPen-based Computer Systems

Source Data Automation

Optical Technology Optical Mark Recognition (OMR) Optical Character Recognition (OCR)

Scanner Digital camera

Magnetic Technology Magnetic Ink Character Recognition (MICR)

Using a light beam to recognise marks, numbers, letters or special characters on a piece of paper which are converted into electrical signals and sent to the computer for processing.

Optical TechnologyOptical Technology

Also called mark-sensing A light beam detects a mark on a document and transmits signals to the computer where software interprets its meaning.5. In a computer each character is represented by one __________.a. bitb. bytec. digitd. word

Optical Mark Recognition (OMR)Optical Mark Recognition (OMR)

Bar code - composed of vertical bars of varying widths which are used to represent data

The bar code readers shine a light beam on the code and the reflected pattern is decoded

Supermarkets use the Universal Product Code (UPC)

OMR Bar CodesOMR Bar Codes

Individual characters on a document are scanned electronically and interpreted by OCR software.

Text can be entered into a word processor avoiding retyping

Some systems can read clear handwriting but most either require the data to be printed in special font (OCR-A) or a very clear typeface (Arial)

Optical Character RecognitionOptical Character Recognition

Text, diagrams and pictures are digitised so that they can be stored as a file.

OCR software is used to translate scanned text into a format that can be input to a word processor document.

Diagrams and pictures can be altered by a graphics editing program.

Image ScannerImage Scanner

Scanners

There are 2 major types of scanner

hand-heldcheap, unreliable, difficult to get a good scan

flat-bedfairly cheap, reliable, can scan bound items

Pictures, either still or moving can be input and stored in a digital format for inclusion in documents, displays or presentations.

Digital CameraDigital Camera

A method of machine-reading characters printed in ink containing magnetised particles.

Mainly used on bank cheques

Magnetic Ink Character Magnetic Ink Character Recognition (MICR)Recognition (MICR)

MICR ApplicationMICR Application

Other Technologies Voice Handwriting Smart card

This falls into two categories: Word recognition-devices which can respond to individually spoken words (discrete word systems)e.g. “Up”, “Left”, “Start”, Stop”

Speech-recognition devices which can recognise sequences of words. (continuous word systems)e.g. input to a word processor

Voice Input / Speech RecognitionVoice Input / Speech Recognition

The subtleties of language are extremely complex

e.g. Time flies like an arrow.Fruit flies like a

banana.

Speech Recognition ProblemsSpeech Recognition Problems

Raw data which has been processed into useable information.

The results of a computing process.

An output device makes the processed information available for use.

OUTPUT

Hard copyrecording text or graphics on a permanent medium, such as paper or film.

Soft copyusing electronic signals to display a temporary image on a screen.

Hard and Soft Copy OutputHard and Soft Copy Output

Line printersband, chain and drum printers. band, chain and drum printers. Images are formed by using Images are formed by using hammers to push the paper and a hammers to push the paper and a ribbon against a raised character ribbon against a raised character embossed on the printing device.embossed on the printing device.

Dot-matrix printersuse a print head containing a use a print head containing a column of pins. Images are formed column of pins. Images are formed by pushing the pins against a by pushing the pins against a ribbon. These have been replaced ribbon. These have been replaced by cheap non-impact printersby cheap non-impact printers

Impact PrintersImpact Printers

PaperRibbon

Characters

Number of characters correspondsto number of print positions

Drum or Cylinder PrinterDrum or Cylinder Printer

Paper

MagnetHammer

Steel print band

Ribbon

Band PrinterBand Printer

One section of chain(48 characters)

Complete chain composed of five 48-character sections

Drive gear

HammersPaper

132 printingpositions

Ribbon

Chain PrinterChain Printer

Inkjetuses a print-head with a number uses a print-head with a number of nozzles to spray drops of of nozzles to spray drops of ink on to the paper.ink on to the paper.

Non-impact PrintersNon-impact Printers

Lasercreates images with a laser beam creates images with a laser beam scanning across an electrically scanning across an electrically charged drum.charged drum.

Non-impact Printers (Cont’d)Non-impact Printers (Cont’d)

Thermaluses heat to transfer an image to uses heat to transfer an image to heat sensitive paper.heat sensitive paper.

Thermal transferuses a heated ribbon or colour uses a heated ribbon or colour transfer sheet that contains transfer sheet that contains particles of ink trapped in wax to particles of ink trapped in wax to transfer an image .transfer an image .

Plotteruses a moving pen to transfer a uses a moving pen to transfer a chart or graph to paper.chart or graph to paper.

Non-impact Printers (Cont’d)Non-impact Printers (Cont’d)

Cathode Ray Tube (Cathode Ray Tube (CRT)raster scanningraster scanningscan rate 80 - 100 times per secondscan rate 80 - 100 times per secondinterlace/non-interlaceinterlace/non-interlaceGraphic standardsGraphic standardsSVGA supports 16 million colours though SVGA supports 16 million colours though only 256 may be displayed only 256 may be displayed simultaneously with 4 screen simultaneously with 4 screen resolutionsresolutions

XGA supports same resolutions but with XGA supports same resolutions but with more colours.more colours.

DisplaysDisplays

Displays Displays (Cont’d)(Cont’d)

Liquid crystal display (LCD) flat screen used in watches, calculators flat screen used in watches, calculators and laptop computersand laptop computers

Flicker free and easy on the eyesFlicker free and easy on the eyes larger displays are expensive but when larger displays are expensive but when the price drops they will replace CRT the price drops they will replace CRT displaysdisplays

Take up much less space than a CRT Take up much less space than a CRT displaydisplay

Displays (Cont’d)Displays (Cont’d)

Voice output is achieved in two ways:synthesis by analysissynthesis by analysis uses human uses human speech as the source of the words and speech as the source of the words and phrases to be synthesised. Reasonably phrases to be synthesised. Reasonably natural sounding.natural sounding.synthesis by rulesynthesis by rule uses complex uses complex linguistic rules to generate linguistic rules to generate artificial speech. Unnatural sounding.artificial speech. Unnatural sounding.

Uses: Telephone enquiries, telling customers their orders are ready in Argos

(or other Catalogue shop)

Voice Voice OutputOutput

Music OutputMusic Output

MIDI (Musical Instrument Digital Interface) a protocol or set of rules for recording and playing music on digital synthesizers

MIDI information tells a synthesizer when to start and stop a specific note and may also include volume and modulation

Waveform audio sound stored and reproduced as a series sound stored and reproduced as a series of samples.of samples.

Representing Non-text DataRepresenting Non-text Data

Graphics bitmap pixel

each pixel requires1 byte for a 256 colour image, i.e. a 640 by 480 pixel display requires 307,200 bytes.

Films 2 hour colour film requires over 66 gigabytes of information

Software The instructions in the form of The instructions in the form of

programs which control the programs which control the operation of a computer, together operation of a computer, together with the associated documentation.with the associated documentation.

What is Software?

Software Categories

System SoftwareSystem SoftwareVersion 1.0

System Software

Version 1.0

Applications Software

System Software

Version 1.0

Software

Software Categories

System Software

Version 1.0

Software

System Software

Version 1.0

Systems Software

System Software

Version 1.0

Applications Software

System Software

Version 1.0

General Purpose

System Software

Version 1.0

Program Language

System Software

Version 1.0

Operating Systems

System Software

Version 1.0

Special Purpose

An application is a task which a user expects a computer to perform.

Applications fall into two categories: General Purpose Special Purpose

Application Software

Software developed to aid the general problem solving needs of people. It is not dedicated to any particular use, but may be used in many different situations. The software are such as;

Word processingcreates, edits, prints text-based documents

Spreadsheetsorganises, calculates and graphs data

General Purpose Applications

General Purpose Applications (Cont’d) Database Management System

organises related data so that it can be easily retrieved

Presentation Graphicscreate professional-looking graphics

Communicationsallow access to the Internet and the World Wide Web

These are applications which are specific to performing a certain task. Managing Accounting Entertainment Education Scientific & Engineering

Special Purpose Applications

Programs that co-ordinate the operation of the computer, facilitate the efficient use of the computer’s resources and assist in the development of application programs.

Operating systems: manage the overall operation of a computer

system. Graphical User Interfaces (GUI)

MS Windows NT, Motif, OpenWindows Programming languages:

used to write programs. Utilities

carry out tasks to assist the management of the computer system, e.g. virus detection programs and device drivers which allow the operating system to communicate with a printer or other peripheral device.

System System SoftwareSoftware

Operating System (OS) The main collection of programs that manages the computers resources to perform operations with efficiency and consistency manages and controls every operation of the computer system

checks that users’ requests are valid and processed in an orderly way

protects one user against another most important piece of software in a computer system

Functions of an OS Interacting with users

translates user intentions into a form the computer understands and also translates any feedback from hardware into a form the user understands.

Making resources available initially sets up the computer system for

operation then loads programs and ensures that their needs are met.

Scheduling resources and jobs determining the order in which jobs are

processed according to predetermined priorities and/or the availability of resources.

Functions of an OS (Cont’d) Monitoring activities

supervising system performance and status, detecting abnormalities in the running of the system and dealing with errors

Housekeeping maintaining the files storage system, compiling statistics on users, programs run and time used.

Security protecting the computer and its software against unauthorised use, maintaining a user authentication system.

Multitasking Operating System

ComputerHardware

OperatingSystem

Program 2

Program 3

Program 1

Multiprogramming Operating System

ComputerHardware

OperatingSystem

Program 2

User User User User User User UserUser

Program 3

Program 1

User Interfaces Command line interface

DIR F: CD \DATA\LEVEL1

Graphical User Interface (GUI)

Icons and menus Windows NT

Various Operating Systems Microsoft Windows

runs on Intel and Intel-compatible processors

Windows NT, 98, 2000 etc. Mac OS

run on Apple Mackintosh computers. Unix

originally designed to run on networked minicomputers, though PC and mainframe versions are available.

Linux an open version of Unix, designed to be free to users.