1.1.7 Block diagram and Working Principle of Computer

1.1.7 Block diagram and Working Principle of Computer

1. BLOCK DIAGRAM AND WORKING
PRINCIPLE OF COMPUTER
By
Mr. V. VEERANAN
M.Sc. Computer Science., Dip. in Yoga.,
Government Arts College, Melur –625 106.

2. 1.1.7 Block diagram and Working
Principle of Computer
Mr. V.Veeranan, M.Sc. Computer Science, Dip. in Yoga

3. Input
Allthedatareceivedbythecomputergoesthrough
theinputunit.Theinputunitcomprisesdifferentdevices.
Likeamouse,keyboard,scanner,etc.Inotherwords,each
ofthesedevicesactsasamediatorbetweentheusersand
thecomputer.Thedatathatistobeprocessedisput
throughtheinputunit.Thecomputeracceptstherawdata
inbinaryform.Itthenprocessesthedata,andproducesthe
desiredoutput.The3majorfunctionsoftheinputunitare
Mr. V.Veeranan, M.Sc. Computer Science, Dip. in Yoga

4. Input
The3majorfunctionsoftheinputunitare:
1.Takethedatatobeprocessedbytheuser.
2.Convertthegivendataintomachine-readableform.
3.Andthen,transmittheconverteddataintothemain
memoryofthecomputer.Thesolepurposeistoconnect
theuserandthecomputer.Inaddition,thiscreateseasy
communicationbetweenthem.
Mr. V.Veeranan, M.Sc. Computer Science, Dip. in Yoga

5. CPU
(Central Processing Unit)
CentralProcessingUnitortheCPU,isthebrainof
thecomputer.Itworksthesamewayahumanbrainworks.
Asthebraincontrolsallhumanactivities,theCPUtoo
controlsalltasks.Moreover,theCPUconductsallthe
arithmeticalandlogicaloperationsinthecomputer.Nowthe
CPUcomprisesoftwounits,namely–ALU(Arithmetic
LogicUnit)andCU(ControlUnit).Bothoftheseunits
workinsync.TheCPUprocessesthedataasawhole.
Mr. V.Veeranan, M.Sc. Computer Science, Dip. in Yoga

6. ALU
(Arithmetic Logic Unit)
TheArithmeticLogicUnitismadeoftwoterms,arithmeticand
logic.Therearetwomajorfunctionsthatthisunitperforms.
1.Datainsertedthroughtheinputunitintotheprimarymemory.
Performsthebasicarithmeticaloperationonit.Likeaddition,
subtraction,multiplication,anddivision.Itperformsallsortsof
calculationsrequiredonthedata.Thensendsbackdatatothe
storage.
2.Theunitisalsoresponsibleforperforminglogicaloperationslike,
AND,OR,Equalto,Lessthan,etc.Inadditiontothisitconducts
merging,sorting,andselectionofthegivendata.
Mr. V.Veeranan, M.Sc. Computer Science, Dip. in Yoga

7. CU
(Control Unit)
Thecontrolunitasthenamesuggestsisthe
controllerofalltheactivities/tasksandoperations.Allthis
isperformedinsidethecomputer.Thememoryunitsendsa
setofinstructionstothecontrolunit.Thenthecontrolunitin
turnconvertsthoseinstructions.Afterthatthese
instructionsareconvertedtocontrolsignals.Thesecontrol
signalshelpinprioritizingandschedulingtheactivities.
Thus,thecontrolunitcoordinatesthetasksinsidethe
computerinsyncwiththeinputandoutputunits.
Mr. V.Veeranan, M.Sc. Computer Science, Dip. in Yoga

8. Memory Unit
Allthedatathathastobeprocessedorhasbeen
processedisstoredinthememoryunit.Thememoryunit
actsasahubofallthedata.Ittransmitsittotherequired
partofthecomputerwhenevernecessary.Thememoryunit
worksinsyncwiththeCPU.Thishelpsinfasteraccessing
andprocessingofthedata.Thus,makingtaskseasierand
faster.
Mr. V.Veeranan, M.Sc. Computer Science, Dip. in Yoga

9. Memory Unit
Therearetwotypesofcomputermemory
PrimaryMemory–Thistypeofmemorycannotstoreavast
amountofdata.Therefore,itisonlyusedtostorerecentdata.
Thedatastoredinthisistemporary.Itcangeterasedoncethe
powerisswitchedoff.Therefore,isalsocalledtemporary
memoryorthemainmemory.RAMstandsforRandomAccess
Memory.Itisanexampleofprimarymemory.Thismemoryis
directlyaccessiblebytheCPU.Itisusedforreadingandwriting
purposes.Fordatatobeprocessed,ithastobefirsttransferred
totheRAMandthentotheCPU.
Mr. V.Veeranan, M.Sc. Computer Science, Dip. in Yoga

10. Memory Unit
Therearetwotypesofcomputermemory
SecondaryMemory–Asexplainedabove,theprimary
memorystorestemporarydata.Thusitcannotbe
accessedinthefuture.Forpermanentstoragepurposes,
secondarymemoryisused.Itisalsocalledthepermanent
memoryortheauxiliarymemory.Theharddiskisan
exampleofsecondarymemory.Eveninapowerfailure
datadoesnotgeterasedeasily
Mr. V.Veeranan, M.Sc. Computer Science, Dip. in Yoga

11. Output
Thereisnothingtobeamazedbywhattheoutputunitis
usedfor.Alltheinformationsenttothecomputeronce
processedisreceivedbytheuserthroughtheoutputunit.
Deviceslikeprinters,monitors,projector,etc.allcomeunder
theoutputunit.Theoutputunitdisplaysthedataeitherinthe
formofasoftcopyorhardcopy.Theprinterisforthehard
copy.Themonitorisforthedisplay.Theoutputunitacceptsthe
datainbinaryformfromthecomputer.Itthenconvertsitintoa
readableformfortheuser.
Mr. V.Veeranan, M.Sc. Computer Science, Dip. in Yoga

12. Mr. V.Veeranan, M.Sc. Computer Science, Dip. in Yoga