Computer Software(Chapter 10)

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COMPUTER SOFTWAREChapter 10


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What Is Hardware AndSoftware

• Hardware

All physical contents of computer are hardware. This form is given to all electrical and mechanical

devices attached to the computer for the purposeof input, process, and storage and outputoperations

• Software Software is a general term used for computer

Programs. A computer program is a planned, stepby step set of instructions that directs thecomputer what to do and how to do


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Types Of Software• System Software

– The programs directly related to the computerhardware and perform tass associated withcontrolling and utili!ing computer hardware.

– System software includes operating systems

" utilities.

• Application Software – An application is a #ob or tas a user wants to

accomplish through a computer. – Application software are programs that help

a user perform a speci$c #ob.


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How it is


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How it is


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Types of System Software

Computers require various types of software to make them useful. These can

be classified as follows:

1. Operatin !ystem

". #tility software


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$

1. Operatin system

%. &pplications software

". #tility softwareOperating System

The operatin system'O!( is the piece of software required by the computer to make

sure that it works correctly and efficiently.

)t manaes the computer and allows the user to communicate with the hardware.

!torin the O! on disk means that it can be easily updated. *indows +ista

and ,- are updated on a daily basis.

odern operatin systems are typically stored on /ard disk and loaded into 0&

when the computer is switched on.


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1. Operatin system


". #tility software

The bootstrap loader

The bootstrap loader is a small but very important

part of the O! which is permanently stored in

0O.

*hen the computer is first switched on the bootstrap loader starts to run.

)t checks the 0& and input2output devices to make sure that they are workin

and then locates the O! on backin storae3 usually on /ard disk but could be

on C4 or even a memory stick.

)t then loads the O! into 0& and the O! takes over control.


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5

1. Operatin system


". #tility software

The main part of the operatin system in 0&

manaes the computer and allows the user to

communicate with the hardware

)t has 6 main functions:

•)nterpretin #ser Commands

• 7ile anaement

• emory anaement

• )nput2Output anaement

• anain -rocesses

• 0esource &llocation


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• )nterpretin #ser Commands

This part of the operatin system accepts

commands 'from a keyboard3 mouse3 etc( and

passes them to the appropriate parts of the

operatin system.

)f the synta9 of the command is not correct then an error messae should be

displayed for the user or the command should be inored.

e.. clickin the left mouse button on a blank area of the

desktop.

• )nterpretin #ser Commands• 7ile anaement• emory anaement• )nput2Output anaement•

anain -rocesses• 0esource &llocation


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• 7ile anaement 1

This part of the O! manaes file operations and

backin storae allocation.

)t allocates blocks of data to particular areas on the backin storae medium. )t

maintains an inde9 of where all the users applications and data are stored so thatthey can be found when requested.

)f you ive a command to load a file from disk3 the Command )nterpreter will passthis instruction to 7ile anaement.

• )nterpretin #ser Commands• 7ile anaement• emory anaement• )nput2Output anaement• anain -rocesses• 0esource &llocation


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C! Topic ; < Computer !oftware v" 1"

• 7ile anaement "

7ile anaement uses its inde9 to work out

e9actly where on the disk the file is stored. e..

Track 183 !ector =.

7ile anaement also maintains the security of the files. )ncluded withthe file information are the access rihts for users. e.. read only.

*hen a file is to be loaded3 7ile anaement will pass the information about

the physical location 'e.. Track 183 !ector =( to )nput2Output anaement.

• )nterpretin #ser Commands• 7ile anaement• emory anaement• )nput2Output anaement• 0esource &llocation• anain -rocesses


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C! Topic ; < Computer !oftware v" 1%

• emory anaement 1

emory anaement decides where

prorams and data are to be placed in 0&.

)t allocates an area of 0& to store the proram.

)t allocates an area of 0& to store the data which the proram is processin.

e.. when you work with *ord then you will have a *orddocument which also requires 0& space

• )nterpretin #ser Commands• 7ile anaement• emory anaement• )nput2Output anaement• 0esource &llocation• anain -rocesses

)t checks to make sure that there is enouh free space to store the new proram

and data.


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C! Topic ; < Computer !oftware v" 1=

• emory anaement "

)t makes sure that prorams do not access0& space allocated to other prorams

)t frees 0& space when prorams are e9ited.


0esource &llocation• anain -rocesses

)t works with )nput2Output anaement to oranise a /ard 4isk for virtual

memory use.


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C! Topic ; < Computer !oftware v" 1;

• )nput2Output anaement 1

)t is the task of )nput2Output anaement to do all

the actual data transfers and issue the appropriatecontrol sinals to the peripheral devices.


*hen a file is to be loaded3 7ile anaement will pass the information about

the physical location 'e.. Track 183 !ector =( to )nput2Output anaement.

)nput2Output anaement has to send the correct sinals to the /ard 4isk to tellit to access Track 183 sector =3 read the data and send it to 0&.


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C! Topic ; < Computer !oftware v" 16

• )nput2Output anaement "

4ifferent types of peripheral devices work indifferent ways.

)nput2Output anaement has to know how to communicate with each device to

allow data transfer to take place.


/ard 4isk 4rives3 C4 4rives3 4+4 drives3 solid state storae devices3 ink>et

printers3 laser printers3 C0T monitors3 ?C4 monitors are all very different.

4evice manufacturers provide drivers'small prorams( which are installed and

become part of )nput2Output anaement. These allow communication to take

place.


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C! Topic ; < Computer !oftware v" 1$



• anain -rocesses 1

& process is defined as bein @ an instance of

a sequence of code in e9ecutionA

& modern O! will typically have several processes on the o at the same time.

e.. Operatin system3 icrosoft *ord3 printin3 virus checker.

-rocesses have to share processor time.

The O! has to manae the processes so that they can be carried out efficiently

and effectively.


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• anain -rocesses "

&t any ive time3 the O! has to decide:

•how lon it should be allowed to use the processor for.

The O! keeps a note of the state of each process and makes sure that each

processor is ettin its fair share of processor time.

• which process is to be allowed to use the processor.


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• 0esource &llocation

The competin processes require accessto resources.

0esources include the processor 3 0& and )nput2Output devices.

)f one process is in the middle of sendin data to the hard disk then another

process cannot be allowed to start sendin its data there too until the first process

has completed its task.

The O! has to manae the resources by controllin how and when the

processes are to be allowed to use them.


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C! Topic ; < Computer !oftware v" "8

1. Operatin system


". #tility softwareUtility Software

#tility software consists of prorams which are desined to help with the maintenance

of the computer and to ensure sure that it works correctly and efficiently.

The distinction between utility software and functions of the operatin system is

rather blurred as modern operatin systems are often bundled with utility software.

e.. disk deframenter3 anti


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C! Topic ; < Computer !oftware v" "1

1. Operatin system


". #tility softwareUtility Software

There are many types of utility software with three e9amples to be looked at in the

/iher course.

• 4isk editor

• 4eframenter

•

+irus checker


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C! Topic ; < Computer !oftware v" ""

• 4isk editor

• 4eframenter

• +irus checker

• 4isk Bditor

& disk editor is a utility proram that lets the user read3

edit3 and write the low


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C! Topic ; < Computer !oftware v" "%

• 4isk editor

• 4eframenter

• +irus checker

• 4eframenter 1

anetic disks are oranised so that they store data in

blocks of a fi9ed sie. 4ependin on its sie3 a file willtypically occupy several blocks.

Dormally data is stored in consecutive blocks on the disk.

This makes sense as the 0ead2*rite head moves to the required track and starts

to read the consecutive blocks.

&fter a time3 the disk starts to fill up and files are edited and deleted. Theremainin free blocks are not necessarily ne9t to each other .


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C! Topic ; < Computer !oftware v" "=

• 4isk editor

• 4eframenter

• +irus checker

• 4eframenter "

*hen new files are saved the blocks may be on different

parts of the disk. )t then takes loner to access thesefiles.

This is called file fragmentation.

& deframenter proram is a utility which reoranises the data on the

disk so that all blocks for a file are stored toether to improve access

times.

This should be done reularly to maintain hard disk performance.


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C! Topic ; < Computer !oftware v" ";

• 4isk editor

• 4eframenter

• +irus checker

• +irus Checker

& virus checker e9amines a computer system to find virus software.

& virus is a proram or prorammin code that replicates

by bein copied or initiatin its copyin to anotherproram3 computer boot sector or document.

)t can be set to e9amine any type of backin storae media3 check email attachments

and files downloaded from the internet.

& ood virus checker will constantly work in the backround checkin for sins of

virus activity.


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Application software

• Application software are the software that aredesigned to satisfy a particular need of aparticular environment.

• All software prepared by us in the computer lab.

• %&amples of application software are'studentrecord software, railway reservation software,income ta& software, word processors etc.

• %&amples include enterprise software, accounting

software, o(ce suites, graphics software andmedia players.


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)ore to understand

about Applicationsoftware*.


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1. Word Processi!Software"

• This software enables the users tocreate and edit documents.

• The most popular e&amples of thistype of software are

• )S'Word,

• WordPad,

• +otepad and some other te&t editors


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#.$ata%ase software"

• atabase is a structured collection ofdata. A computer database relies ondatabase software to organi!e the dataand enable the database users toachieve database operations.

• %&amples are -racle, )SAccess, etc.


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.Spreadsheet software• . They si&'(ate paper wor)sheets %y

disp(ayi! &'(tip(e ce((s that &a)e 'pa !rid.

• Spreadsheet software a((ows 'sers toperfor& ca(c'(atios

• E*a&p(es" E*ce(


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+.M'(ti&edia Software /

• They a((ow the 'sers to create ad p(aya'dio ad ,ideo &edia

• A'dio co,erters- p(ayers- %'rers-

,ideo ecoders ad decoders are so&efor&s of &'(ti&edia software

• E*a&p(es of this type of softwareic('de Rea( P(ayer ad Media P(ayer.


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co&e 'der Presetatio

Software /

• The software that is 'sed to

disp(ay ifor&atio i thefor& of a s(ide show is )owas presetatio software

• Microsoft PowerPoit is the

%est e*a&p(e of presetatiosoftware.

.Powerf'( Presetatio/

Computer Software(Chapter 10)

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