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ComputerApplicationsin

MEP203

Dr.Eng.MohamedElGhandour

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a arepresen a on n acompu er

Thebinarysystem

Theoctalandhexadecimalsystems

TypesofDataStoredinMemory

ComputerLanguages Highlevellanguage

Specificationsofawelldesignedprogram

Flowcharts IntroductiontoFortran

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DATAREPRESENTATIONINACOMPUTER

Computermemoriesarecomposedofbillionsofindividualswitches,eachofwhich

canbeONorOFF,butnotatastateinbetween.Eachswitchrepresentsonebinary

digit(alsocalledabit);theONstateisinterpretedasabinary1,andtheOFFstate

isinterpretedasabinary0.

Byte

Abyteisagroupof8bitsthatareusedtogethertorepresentabinarynumber.Thebyteisthefundamentalunitusedtomeasurethecapacityofacomputer'smemory.

Word

Thenextlargergroupingofbitsinancomputeriscalledaword.Aword

consistsof2,4,ormoreconsecutivebytesthatareusedtorepresentasinglenumberin

memory.Thesizeofawordvariesfromcomputertocomputer,sowordsarenota

particularly

good

way

to

judge

the

size

of

computer

memories.

Modern

CPUs

tend

to

.

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Inthebinarysystem,thereareonlytwodigits:

0and1,eachofthemismulti liedb 2tothe

powerofpositionstartswithzeroatthe

, ,

(1or0)*22+(1or0)*21+ (1or0)*20

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TheDecimalsystem

TheHexadecimalsystem

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ea or oa ngpo n

Representsfractions0.24,1.5,etc

RepresentsverysmallandverylargenumbersTherange of4byterealnumbersisfromabout1038 to1038.Notethat

therealdatatypecanrepresentnumbersmuchlargerormuchsmallerthanintegerscan,butonlywithsevensignificantdigitsofprecision.

enava uew more anseven g so prec s on ss ore narea variable,onlythemostsignificant7bitsofthenumberwillbepreserved.Theremaining informationwillbelostforever.Forexam le if the value 12 345 678.9 is stored in a real variable on a PCitwillberoundedoffto12,345,680.0.Thisdifferencebetweentheoriginalvalueandthenumberstoredinthecomputerisknownas

roundofferror.

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Computer

anguages

ow eve

Lan ua e

g eve

Lan ua e Fortran

C++ Java

Machine Language

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Executable

file

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Specificationsofawelldesigned

program

Correctan accurate

Easytounderstand Easytomaintainandupdate

Reliable

ex e

Easy

to

use

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Fortran (FormulaTranslatingSystem)isa

isespeciallysuitedtonumericcomputation

.

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or ran s ory

OriginallydevelopedbyIBMattheircampusin,

FORTRANI,II,III,IV

F RTR N

,

F rst

N

stan arFORTRAN77,

Fortran90,

Fortran95,Fortran2003,

Fortran2008,

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