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Information Technologyfor Managers

Session 6By

Prof. Arun Mishra

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L earning Objectives

I n this session you will learn:Machine Language

Assembly LanguageHigh-level LanguageObject-oriented Language

CompilersI nterpretersSubroutines

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C omputer L anguage

A language that is acceptable to acomputer system is called computer

language or programming language.A computer Language is used by aprogrammer to instruct a computerwhat he wants to do something.

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Types of C omputer L anguage

Machine Level LanguageAssembly Language

High Level LanguageFourth level LanguageObject oriented Language.

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Machine L evel L anguage

Machine language of a computer iswritten as string of binary 1 & o.

Example- 10001,101010A computer can be programmed tounderstand many different computerlanguages, but there is only one

language understood by computerwithout using a translation program.This Language is called Machine LevelLanguage or language of computer.

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Machine language instruction format

I t has two parts:OPCODE (operation code)- tells the

computer what function to perform.OPERAND- tells computer where tofind or store the data or instructionwhich are to be manipulated.

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Operations included in instructionformat of machine language

Arithmetic operationsLogical operationsBranch operations for transfer of controlto the address given in operand field.Data movement operations for movingdata between memory location &

registers.Data movement operations for movingdata from 1 computer to another. Or 1input device to another output device.

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L imitation of Machine level language

Machine dependent.Difficult to program.

Error prone- tough to rememberopcodes.Difficult to modify.

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A ssembly L anguage

A Language which allows instructionand storage location to be

represented by letters and symbols,instead of numbers is calledAssembly Language.A program written in An assemblylanguage is called an assemblylanguage program.

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Merits of A ssembly L anguage over Machine L anguage

I t uses alpha numeric codes instead of numeric codes for instructions. e.g.-We use ADD instead of 1110 for theinstruction to Add.I t allows Storage Location to berepresented in the form of

Alphanumeric address instead of numeric address. e.g.- memorylocation 1000,1001,1002 may berepresented as F I RST, SCND, ANSR.

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Merits of A ssembly L anguage over Machine L anguage

I t provides additional instructions,called pseudo instructions in instructionset.

e.g.- pseudo instruction tell things like:-START program AT 0000START data AT 1000SET AS I DE an address for FRST

SET AS I DE an address for SCND

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A ssembler

An assembler is a system software whichtranslates an assembly language into itsequivalent machine language.A computer can directly execute onlymachine language program, which usenumbers for representing instructions andstorage locations.

So assembly language program must beconverted into its equivalent machinelanguage program.This translation is done with the help of

Translator program known as ASSEMBLER.

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A dvantages of A ssembly L anguage

Easier to understand and use.Easier to modify.

Easy to locate and correct errors.

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Ex ample of A ssembly language

Microprocessor language.

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H igh L evel L anguage

High level language were designed toovercome the limitations of low level

languages (Machine language & Assembly language).High level enabled the use of computers to solve problems even bynon experts.

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C haracteristic of H igh L evellanguage

I t is machine independent.I t do not require the programmers toknow anything about the internalstructure of computer on which programwill be executed.I t do not deal with the machine Levelcoding.They deal with the high level codingenabling the programmer to writeinstruction using ENGL I SH words andfamiliar symbol & expression.

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C ompiler

High level language must beconverted into its equivalent machine

language program, before it isexecuted.This translation is Done by translatorprogram known as COMP I LER.Compiler is program which translatesHigh level language into itsequivalent machine languageprogram.

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C ompiler

A compiler can translate only thosesource programs which have been

written in the language for which thecompiler is meant. E.g.- FORTRANcompiler is only capable of translatingsource program written in FORTRAN.

So each computer requires separatecompiler for each high level languageit supports.

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Interpreter

I t is also used to translate HighLevel language to Machine Level

Language.But it takes one statement at atime, translates its and immediatelyexecutes the resulting machinelanguage instruction.I t translate 1 instruction at a time.

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Interpreter

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A dvantage of H IGH level L anguage

Machine I ndependentEasier to learn & Use.

Very less errors.Low program preparation cost.Saves time.

Better documentation.Easy to maintain.

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D isadvantages of H igh levelL anguage

Low efficiency- as it first convertinto machine language then

executed.

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Ex ample of H igh level L anguage

FortranCobol

PascalC

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F ourth generation languageI t is also known as non-procedurallanguage.These languages consists of a variety of programming languages that enable usersto specify the result they want, while thecomputer determines the sequence of instruction that will accomplish those

result.Fourth generation language simplify andaccelerates software development as wellas reduce programming errors.

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Ex ample of fourth generationlanguage

SQL Standard Query LanguagePRO LOG: an artificial intelligence

language that applies rules to data toarrive at solutions.J ava

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Object oriented L anguage

An object in object oriented programminglanguage consist of data and the actionsthat can be performed on the data.

OOP language are distinguished fromother language as they combine data andprocedures into objects, whereas theother programming language separates

data from the procedures or actions thatare to be performed on them.Examples: JAVA, C++.

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C haracteristic of good programminglanguage

S implicity - Must be simple & easy tolearn.

N aturalness -should be natural forthe application area for which it isdesigned.Ab straction -Means ability to define& then use complicated structure oroperations in ways that allow manyof the details to be ignored.

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C haracteristic of good programminglanguage

E fficiency -Good programminglanguage are efficiently translated into

machine codes, are efficientlyexecuted and consumes less space inmemory.C ompactness - Programmer shouldbe able to express intendedoperations concisely.Ex tensi b ility - should allow extensionin future.

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Any Q uestions?

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QuestionsQuestionsWhat is assembly language? What are itsadvantages over Machine Language?What are the characteristic features of high level language. What are itsadvantages over Low Level Languages?Write short notes on:

AssemblerCompilerI nterpreter

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