BasicComputerSystem

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RAM CPU

I/ODevices(or)PeripeheralsMEMORY DMA

DirectMemoryAccesscontroller

ExternalUnit External

Externalunits

Binarynumbersystem…Quickreview

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BinaryNumbersystem-Oand1representa8on

Example:(Decimal)42=4x101+2x100Weknowthis!J(Binary)42=1x25+0x24+1x23+0x22+1x21+0x20

=32+8+2SothepaVernwillbe:101010(Verifythereverse!)Hence:Withjust2digits–YY–{0,1,2,3}–4dis_nctnumbersWithjust3digits–YYY–{0,1,…,7}–8dis_nctnumbersWithjust4digits–YYYY–{0,1,2,…,15}–16dis_nctnumbers…Withkdigits:(YYYY….YY)–{0,1,….,2k-1}–(2k)dis_nctnumbers

Binarynumbersystem…Quickreview

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Hexa-decimal–ValidNumbers:{0,1,…,15}andtheyarerepresentedas

{0,1,2…,9,A,B,C,D,E,F}Example:(Hexa-Decimal)42=2x161+10x160(=32+10)SothepaVernwillbe:2A(Verifythereverse!)Weusuallyrepresentahexadecimalnumberas‘2AH’;Hence:4E8H=1024+224+8=1256(decimal)

ComputerSystem…Cont’d

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RAM...

1Byte=8Bits(eachslot)

Addressing:EachslothasauniqueaddressAddressisrepresentedasabinarywordRAM8Slotsimpliesweneed3bitnumberrepresen_ng(addressing)eachslot;RAM16Slotsimpliesweneed4bitnumberrepresen_ng(addressing)eachslot;

01001010

LeastSignificantBit(LSB)MostSignificantBit(MSB)

01001010-ThispaVernisrepresentedasahexa-decimalnumber4AintheMemoryfortheeaseofreading

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ComputerSystem…Cont’d

APPLICATION

COMPUTERPROGRAM(Languages–C/C++/Java/Assembly…)

MODELING(Mathema_cal/Sta_s_cal/Empirical,etc)

Compile–Link–ExecutableàRun!

Howdoesourprogramgetexecuted?Whatdowemeanby“running”aprogram?

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Programmustbebroughttothememory(RAM)forExecu_on;Eachlineoftheprogramwillbetranslatedintoasetofmachineinstruc-ons(0’sand1’s)andallinstruc_onsarestoredinRAMinacon_guousorder;Instruc_onsarefetchedfromRAM,oneata_me,andgetexecutedintheCPU;Allsuchinstruc_onswillliveinthememoryun_ltheen_reprogramgetsexecuted;

ProgramExecu_on/Running

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ProgramExecu_on/Running…(Cont’d)

prins(“MynameisBV\n”);/*Csyntax*/

101010111100010101010010100111101100

Example

Morethan1byte!!

101010111100010101010010100111101100

Hence,

Inthiscase,thisinstruc_onoccupies5bytes;Thelast4mostsignificantbitswillbepaddedwith0s.

ControlStructuresn  Analgorithmisasetofinstruc_ons,whicharefollowedsequen_allybydefault.

n  However,some_mesweneedtochangethedefaultsequen_alflow.

n  Wewillstudy3controlstructuresusedpredominantlyinprogramming

-Sequence -Selec_on -Repe__on

(c)BharadwajVDeptofECENUS(2017) ACK:ThanksDr.Alanforcontrolstructuresslides

True False? True

False ?

ControlStructures:Sequence

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n  Task:Computetheaverageofthreeintegers

Eachboxrepresentsavariable.Importantconcepts:Eachvariablehasauniquenameandcontainsavalue.

Apossiblealgorithm:

entervaluesfornum1,num2,num3aveß(num1+num2+num3)/3printave

Variablesused:num1 num2 num3

ave

Anotherpossiblealgorithm:

entervaluesfornum1,num2,num3totalß(num1+num2+num3)aveßtotal/3printave

Variablesused:num1 num2 num3

ave

total

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ControlStructures:Selec_on

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n  Task:Arrangetwointegersinascendingorder(sort)AlgorithmA:

entervaluesfornum1,num2//Assignsmallernumberintofinal1,//andlargernumberintofinal2if(num1<num2)

then final1ßnum1 final2ßnum2

else final1ßnum2 final2ßnum1//Transfervaluesinfinal1,final2backtonum1,num2num1ßfinal1num2ßfinal2//Displaysortedintegersprintnum1,num2

Variablesused:

num1 num2

final1 final2

True False?

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ControlStructures:Repe__on

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n  Task:Findsumofposi_veintegersupton(assumen>0)

Algorithm:entervalueforn /*Ini8aliseacountercountto1,andansto0*/countß1ansß0

REPEAT_UNTIL(count<=n)do ansßans+count //addcounttoans

countßcount+1 //increasecountby1//Displayanswerprintans

Variablesused:

n

count

ans

Ini_alisa_onisveryimportant!

True

False?

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Algorithm

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n  Analgorithmisawell-definedcomputa_onalprocedureconsis_ngofasetofinstrucCons,thattakessomevalueorsetofvaluesasinput,andproducessomevalueorsetofvaluesasoutput.

‘Algorithm’stemsfrom‘Algoritmi’,theLa_nformofal-Khwārizmī,aPersianmathema_cian,astronomerandgeographer.Source:hVp://en.wikipedia.org/wiki/Algorithm

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Inputs Output(s)

Algorithm

Algorithm

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n  Waysofrepresen_nganalgorithm:

Flowchart Pseudocode

lynda.com

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Flow-Charts

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• VisualRepresenta_onofthework-flow/process-flow

• Pre-definedsymbolsandrepresenta_onsthatcapturetheflow• TypicallystartswithaSTARTblockandendswithanENDblock• Forverylargeflow-chartsconnectorsaregenerallyused

Flow

-cha

rtsC

ont’d

…

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Flow-Chart/Algorithm:Example1

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Example2-Flow-Chart/Algorithm

START

END

x,y,z=0

Computethevaluesusingfunc_ons:

F(x,y),G(y,z)andH(x,z)

IsG(y,z)>

F(x,y)?

UpdatexusingQ(x)

DecreaseyusingP(y)

Displaythefunc_onvalues

YES

NO

Systema_cdesignprocessinvolvesdrawingflow-charts/wri_ngpseudocodesYoushoulddrawflow-chartsinallthethreelabassignmentswhichreflectsyourdesign;Drawingflow-chartcarriesmarks.

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