Software and os ch5

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Abdul Wajid Khan Yousafzai

Logical Component of a Computer We can not touch These are in form of instructions that

tell the computer that what to do It can not executed without hardware. If any problem in software then it will

reinstall.

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Software may be in the form of System Software Application Software

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It controls a computer’s internal function System software manages the fundamental

operations of your computer Operating system Utilities Library Programming Languages

It also control mouse ,printer, Monitors Examples Operating System Language Software

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Is collection of System software An interface between applications and hardware Hardware needs a manager to tell it

what to do when to do it how to do it

The (OS) controls all input output ProcessingUses

It manages the data and the memory and appearance

Make the computer system convenient to use Execute user programs and make solving user

problems easier.5

Efficiency Allows computer system resources to be used in an efficient

manner Ability to evolve

Permit effective development, testing, and introduction of new system functions without interfering with service

Communication with hardware They provide the way for application software to

communicate with hardware Transfer data

They manage the transfer of data to and from the various peripherals

System Security They manage system security. Many operating systems

allocate certain rights to user

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Hardware

Operating System

Software

ComputerUser

Window 98 Window 2000 Window XP Window Vista Linux Unix

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User interface is what you see when you turn on the computer

It consists of the cursors, prompts, icons and menus etc

Which allow you to get something done using your computer

Ideally the user interface should be as easy to use as possible

User interface may be Command driven interface Menu driven interface Graphical user interface

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With a command driven interface, you type in an instruction, which is usually abbreviated, in order to get something done.

Are not easy to use A set of commands used to interact with

computer is called command language It requires exact spelling and punctuation Advantage: Commands for different software application

are rarely the same so user can be faster to use and have learnt all the commands

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The user enter data and instruction by using menus

Easy to use because the user has not remember the syntax of commands

User can make a selection by using either a mouse or a keyboard

Drop down list

Present options

Both Microsoft Windows

and Apple Macintosh

programs are menu driven

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Is a visual environment that is used by the user to communicate with computer

It uses windows ,icons, menus and other graphical objects to issue commands.

Easy to use Easy to learn Attractive WIMP: stands for windows,

and pointing devices which describes the features of GUI

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More immediate access store and secondary store

More powerful processor and graphical card

Slower then executing Greater no of operations is required

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Consistency Positioning of items on the screen Use of colour Use of sound Availability of help

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A type of system software that is used to solve particular problem.

Designed to make life easier for computer users.

Utility programs perform thousands of task Renaming files Listing file on a disk Deleting files Copying files Sending files to a printer Storing data Backing up files

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File Viewer Is used to view and manage files in computer system. Window Explorer File Compressor: Is used to shrink the size of files Winzip and WinRARDiagnostic Utilities: is used to detect problem in hardware and software AntiVirus Disk Defragmenter Backup utility Data Recovery Utility Task Manager utility Disk Cleanup Personal Firewall Spyware Remover

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Application software enables you to perform specific computer tasks, such as document production, spreadsheet calculations, and database management

Any program that processes data for a userUsers prepare these

Packaged software Custom Software Integrated software Bespoke Software Shareware Free Ware Public Domain Software

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Single program Kind of a Jack-of-all-trades Shares a common set of commands Commands are common throughout Moving data from one program to another is easy Which combine features from all below products Multiple functionality

Word processor, spreadsheet, DBMS, Presentation graphics and communication software

Advantages Lower cost Simpler Capabilities not as extensive

Disadvantages: Tend to be strong in one area and weak in others

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It is particular user or organization. The program are well tested Is available for different types of users Documentation are very good Examples: Word processing software such as word and

word perfect Spread sheet software such as Lotus 1-2-3

and Excel Data base software such as Access

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Is developed to meet the requirement of particular company or industry.

If packaged software does not fulfill the requirement of an organization, it has to develop a custom software by hiring a programmer.

The cost of custom software is higher.

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The instructions that tell the computer what to do is called program

Programmer: Who writes or design the program in

any language. Computer can understand only the

binary code

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Humans can use different languages to communicate

The instructions are written in a languages which are easy to understand

Programming languages may be in the form of

High level Languages Low Level Languages

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Are languages that are easy for the computer to understand but more difficult for the programmer

Each instruction usually translates into one machine code instruction

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Machine Language Assembly Language

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Is the language that directly understood by the machine

It consists of series of a 0s and 1s It is a machine specific it mean that one

computer’s machine code will not be understand by other computer type

It needs no translation so that way it is very fast

A lot of games or simulation programs are written in machine code for this reason

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It is easier for the programmer to use and to debug Once a program has been written in assembly language it

needs translating into machine code by software called assembler

Is a low level language which allows the programmer to use Mnemonics and symbolic address

Mnemonics: Is a word or set of letters which can be used to represent a

function code and which is easy to remember Example: LDA use for Load Accumulation JMP for jump instruction and ADD are mnemonics Symbolic Address: Is a name inverted by the programmer to identify a location Loop ,value and prnt are symbolic addresses

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Is developed with the programmer in mind rather than the computer

High level language instructions are similar to English which mean programming is more easier.

Once a program has been written it can be used on different computers with little alteration

It can be translated into machine code by a compiler and then run

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Simple instruction similar to English make high level language easy to understand

It is easy to correct errors and test programs

Programs written in high level language can be used on different makes of computer

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COBOL: common business oriented languagePurpose: easily understand language for

commercial data processing applicationFeatures: look like English Statement Good facilities for file handling

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Beginners all purpose symbolic instruction code

Purpose: Teaching language for interactive work Features: Every line has to be numbered Easy for beginners to learn Many different versions

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Formula translation Purpose : For scientific use. Usually batch work Features: Lacks of statements which makes

program structure clear Designed to be used with cards as

input and a line printer as a output

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Purpose : An educational language that

encourage logical thinking Features : New instructions can be added and can

be defined Facilities to process lists

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Purpose : To allow clear structuring of data and program Features: All variables are declared before they can be

used. Encourages clear structure and stepwise

refinement New procedures ,functions and data types can

be defined and added in

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A language especially suited for writing software used to search for things on the internet.

HTML Hypertext markup language A language used for the development

of websites

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Source code Is written in high

language or assembly language

Easy to understand Easy to modify Contain fewer

statements It contain .exe

extension

Object code Is written in machine

language through compiler

difficult to understand

Difficult to modify More statement than

source code It contain .obj

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Are part of the system software and are used to convert the programs commands into machine code

There are three types of translation program

Compiler Interpreters Assemblers

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Is software that converts the whole of a program written in a high level language into machine code in one go.

There are no mistakes in the program the complete program is converted to machine code

If a program needs to be altered at a later date the original source code is altered and program recompiled

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Each instructions in turn, converts it to machine code and then caries it out

It run one line at a time The computer recognizes each

instruction

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Compiler Converts a program into

a machine code as a whole

Creates object code file Converts high level

programs that can be executed in many times

Execution is fast Displays syntax errors

after compiling the whole program

Interpreter Converts a program into

machine code statement by statement

Object file is not created Converts high level

programs each time it is executed

Program execution is slow

Displays the syntax error on each statement of program

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Is a program which translates a program written in as assembly language into are in machine code

The main functions of an assembler are to : Translate an assembly language source program

into a machine code object program Work out where to store the object program and its

data Detects errors in the source program and say what

they are Link the program to any other programs or routines

it uses Print a listing of the source and object programs

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Assembly Language

Code

High Level

LanguageCode

High Level

LanguageCode

InterpreterCompiler Assembler

Machine Code