Introduction to Computer System-ppt.pdf

Computer science

1. Chapter-1
Introduction To
Computer System
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2. Introduction to Computer
Computerisanadvancedelectronicdevicethattakesraw
dataasinputfromtheuserandprocessesthesedataunder
thecontrolofsetofinstructions(calledprogram)andgives
theresult(output)andsavesoutputforthefutureuse.
Acomputerisacombinationofhardwareand
softwareresourceswhichintegratetogetherandprovides
variousfunctionalitiestotheuser.Hardwarearethephysical
componentsofacomputerliketheprocessor,memory
devices,monitor,keyboardetc.whilesoftwareisthesetof
programsorinstructionsthatarerequiredbythehardware
resourcestoperformvariousoperationsasperthe
requirementofusers.
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3. Introduction to Computer
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4. EVOLUTION OF COMPUTING DEVICE
FirstGeneration(1940-56):
Thefirstgenerationcomputersusedvacuumtubes&
machinelanguagewasusedforgivingtheinstructions.These
computerswerelargeinsize&theirprogrammingwasdifficulttask.
Theelectricityconsumptionwasveryhigh.Somecomputersofthis
generationareENIAC,EDVAC,EDSAC&UNIVAC-1.
Inthisgeneration,mainlybatchprocessing
operatingsystemwasused.Punchcards,papertape,andmagnetic
tapewasusedasinputandoutputdevices.Thecomputersinthis
generationusedmachinecodeastheprogramminglanguage.
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5. SecondGeneration(1956-63):
In2ndgenerationcomputers,vacuumtubeswerereplacedby
transistors.Theyrequiredonly1/10ofpowerrequiredby
tubes.Thisgenerationcomputersgeneratedlessheat&were
reliable.Thefirstoperatingsystemdevelopedinthis
generation.IBM1620,IBM7094,CDC1604aretheexamples
ofthisgenerationscomputers.
In2
nd
generation,magneticcoreswereused
astheprimarymemoryandmagnetictapeandmagneticdisks
assecondarystoragedevices.
Inthisgeneration,assemblylanguageandhigh-level
programminglanguageslikeFORTRAN,COBOLwereused.The
computersusedbatchprocessingandmultiprogramming
operatingsystem.
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6. ThirdGeneration(1964-71):
The3rdgenerationcomputersreplacedtransistorswith
Integratedcircuitknownaschip.FromSmallscaleintegrated
circuitswhichhad10transistorsperchip,technology
developedtoMSIcircuitswith100transistorsperchip.These
computersweresmaller,faster&morereliable.Highlevel
languagesinventedinthisgeneration.
TheICwasinventedbyJackKilby.This
developmentmadecomputerssmallerinsize,reliable,and
efficient.Inthisgenerationremoteprocessing,time-sharing,
multiprogrammingoperatingsystemwereused.High-level
languages(FORTRAN-IITOIV,COBOL,PASCALPL/1,BASIC,
ALGOL-68etc.)wereusedduringthisgeneration.IBM-360
series,Honeywell-6000aresomeexamplesofcomputersin3
rd
generation..
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7. FourthGeneration(1972-1980):
LSI&VLSIwereusedinthisgeneration.Asaresult
microprocessorscameintoexistence.Thecomputersusingthis
technologyknowntobeMicroComputer.Highcapacityhard
diskwereinvented.Thereisgreatdevelopmentindata
communication.
Fourthgenerationcomputersbecame
morepowerful,compact,reliable,andaffordable.Asaresult,it
gaverisetoPersonalComputer(PC)revolution.Inthis
generation,timesharing,realtimenetworks,distributed
operatingsystemwereused.Allthehigh-levellanguageslike
C,C++,DBASEetc.,wereusedinthisgeneration.
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8. FifthGeneration(1980-Present&Beyond):
Fifthgenerationcomputingdevices,basedonartificial
intelligence,arestillindevelopment,thoughtherearesome
applications,suchasvoicerecognition,thatarebeingused
today.Theuseofparallelprocessingandsuperconductorsis
helpingtomakeartificialintelligenceareality.Quantum
computationandmolecularandnanotechnologywillradically
changethefaceofcomputersinyearstocome.
Some computer types of this generation are −
Desktop
Laptop
Note Book
Ultra Book
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9. COMPONENT OF A COMPUTER SYSTEM
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10. Intheabovediagram,bothcontrol(controlunitor
CU)andarithmetic&logicunit(ALU)combinelycalled
asCentralProcessingUnit(CPU).
Let'sdescribeaboutallthepartsasincludedintheabove
diagramonebyone.
TheProcessorUnit(CPU)
Itisthebrainofthecomputersystem.Allmajorcalculation
andcomparisonsaremadeinsidetheCPUanditisalso
responsibleforactivationandcontrollingtheoperationof
otherunit.
Thisunitconsistsoftwomajorcomponents,thatarearithmetic
logicunit(ALU)andcontrolunit(CU).
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11. ArithmeticLogicUnit(ALU)
Arithmeticlogicunitperformsallarithmeticoperationssuchas
addition,subtraction,multiplicationanddivision.Italsouses
logicoperationforcomparisonlikecomparisonordecision
making(>,<,<=,>=,=etc.).
ControlUnit(CU)
ThecontrolunitofaCPUcontrolstheentireoperationofthe
computer.Italsocontrolsalldevicessuchasmemory,
input/outputdevicesconnectedtotheCPU.
CUfetchesinstructionsfrommemory,decodestheinstruction,
interpretstheinstructiontoknowwhatthetaskaretobe
performedandsendssuitablecontrolsignalstotheother
componentstoperformforthenecessarystepstoexecutethe
instruction.
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12. Input/OutputUnit
Theinput/outputunitconsistsofdevicesusedtotransmit
informationbetweentheexternalworldandcomputer
memory.
Theinformationfedthroughtheinputunitisstoredin
computer'smemoryforprocessingandthefinalresultstored
inmemorycanberecordedordisplayontheoutputmedium.
Memoryunit
Itisanessentialcomponentofadigitalcomputer.Itiswhere
alldataintermediateandfindresultsarestored.Thedataread
fromthemainstorageoraninputunitaretransferredto
thecomputer'smemorywheretheyareavailablefor
processing.Thismemoryunitisusedtoholdtheinstructions
tobeexecutedanddatatobeprocesses.
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13. PrimaryMemory:
Primarymemoryhasdirectlinkwithinputunitandoutput
unit.Itstorestheinputdata,intermediatecalculation,result.
SecondaryMemory:
Theprimarystorageisnotabletostoredatapermanentlyfor
futureuse.Sosomeothertypesofstoragetechnologyis
requiredtostorethedatapermanentlyforlongtime,itis
calledsecondaryorauxiliarymemory.
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Input & Output Device
InputDevice:
Inputdevicesarethosedeviceswhichhelptoenterdatainto
computersystem.E.g.Keyboad,Mouse,Touchscreen,Barcode
Reader,Scanner,MICR,OMRetc.
BarCodeReaderMICRusedinBank OMR

15. KEYBOARD:Thisisthemostcommoninputdevicewhichusesan
arrangementofbuttonsorkeys.Inakeyboardeachpressofakey
typicallycorrespondstoasinglewrittensymbol.Howeversomesymbols
requirepressingandholdingseveralkeyssimultaneouslyorinsequence.
Whilemostkeyboardkeysproduceletters,numbersorcharacters,other
keysorsimultaneouskeypressescanproduceactionsorcomputer
commands.
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Mouse:
Acomputermouse(pluralmiceormouses)isahand-
heldpointingdevicethatdetectstwo-dimensionalmotion
relativetoasurface.Thismotionistypicallytranslatedintothe
motionofapointeronadisplay,whichallowsasmooth
controlofthegraphicaluserinterfaceofacomputer.

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Scanner:
Scannerisadevicethatopticallyscans
images,printedtext,handwriting,oran
object,andconvertsittodigitalimage.
JOYSTICK:
Ajoystickisaninputdeviceconsistingofastick
thatpivotsonabaseandreportsitsangleor
directiontothedeviceitiscontrolling.
Manypeopleusejoysticksoncomputergamesinvolvingflightsuchas
flightsimulator.
Joysticksareoftenusedtocontrolvideogames,andusuallyhaveone
ormorepush-buttonswhosestatecanalsobereadbythecomputer

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OutputDevice:
Output devices are those devices which help to display the
processed information. Eg. Monitor, Printer, Plotter, Projector
etc.

19. PRINTER:
Printer produces result on the paper.
T h e r e are various types of printers available in the market:
DOT MATRIX PRINTER:
Uses ribbon and hammer technology.
Its quality is not very good. It prints by making the object using
small dots.
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20. INKJET PRINTER:
It creates a digital image by propelling
droplets of ink onto the paper.
LASERJETPRINTER:
Theyuseslasertechnologytoprintdocuments.Itproducehighquality
printingatveryhighspeed.
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21. MONITOR
➢Itistheprimaryoutputdevicewherewe
seetheoutput.ItlookslikeTV.
➢ItisalsoknownasVDU(VisualDisplayUnit).
➢ItsdisplaymaybeintheformofCRT
LED,LCD.
1.CRT(CATHODERAYTUBE)
2.LCD(LIQUIDCRYSTALDISPLAY)
3.LED(LIGHTEMITTINGDIODE)
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22. MEMORY UNITS: Memory is used to store the data for later
reference.The smallest unit is bit, which mean either 0 or 1.
❑1 bit = 0 or 1
❑1 Byte = 8 bits
❑1 Nibble = 4 bits
❑1 Kilo Byte = 1024 Byte= 2
10
Byte
❑1 Mega Byte = 1024 KB= 2
10
KB
❑1 Giga Byte = 1024 MB= 2
10
MB
❑1 TeraByte = 1024 GB= 2
10
GB
❑1 PetaByte =1024 TB= 2
10
TB
❑1 ExaByte =1024 PB= 2
10
PB
❑1 ZettaByte = 1024 EB= 2
10
EB
❑1 YottaByte = 1024 ZB= 2
10
ZB
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23. PRIMARY MEMORY
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24. SECONDARY MEMORY
Theprimarystorageisnotabletostoredatapermanentlyfor
futureuse.Sosomeothertypesofstoragetechnologyis
requiredtostorethedatapermanentlyforlongtime,itis
calledsecondaryorauxiliarystorage.
EXAMPLES OF SECONDARY STORAGE
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25. DATA DELETION AND ITS RECOVERY ,
SECURITY CONCERN
Youcanconvenientlydeletepersonaldatastoredincomputer
system,surveyresponses,tickets,andcontacts,nomatter
wherethedataoriginated.
Examplesofreasonsfordeletingthedataare:
❑Freeingthediskspace
❑Removingduplicateorunnecessarydatatoavoidconfusion
❑Makingsensitiveinformationunavailabletoothers
❑Removinganoperatingsystemorblankingaharddrive
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26. DATA RECOVERY
❑incomputing,datarecoveryisaprocessofsalvaging
(retrieving)inaccessible,lost,corrupted,damagedor
formatteddatafromsecondarystorageandremovable
mediaorfiles,whenthedatastoredinthemcannotbe
accessedinanormalway.
❑Themostcommondatarecoveryscenarioinvolvesan
operatingsystemfailure,malfunctionofastoragedevice,
logicalfailureofstoragedevices,accidentaldamageor
deletion,etc.(typically,onasingle-drive,single-partition,
single-OSsystem),inwhichcasetheultimategoalissimply
tocopyallimportantfilesfromthedamagedmediato
anothernewdrive.
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27. COMPUTER SECURITY
❑ItisalsoknownasITsecurity,istheprotectionof
informationsystemsfromtheftordamagetothehardware,
thesoftware,andtotheinformationonthem,aswellas
fromdisruptionormisdirectionoftheservicestheyprovide.
❑Itincludescontrollingphysicalaccesstothehardware,as
wellasprotectingagainstharmthatmaycomevianetwork
access,dataandcodeinjection,andduetomalpracticeby
operators,whetherintentional,accidental,orduetothem
beingtrickedintodeviatingfromsecureprocedures.
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28. CONCERNS OF COMPUTER SECURITY
Computer Security is concerned with four main areas:
1. Confidentiality:-Only authorized users can access the data resources
and information.
2. Integrity:-Only authorized users should be able to modify the data
when needed.
3. Availability:-Data should be available to users when needed.
4. Authentication:-are you really communicating with whom you think
you are communicating with
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29. SOFTWARE AND ITS TYPE
SOFTWARE:Software,simplyarethecomputerprograms.The
instructionsgiventothecomputerintheformofaprogramis
calledSoftware.Softwareisthesetofprograms,whichare
usedfordifferentpurposes.Alltheprogramsusedincomputer
toperformspecifictaskiscalledSoftware.
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30. TYPES OF SOFTWARE
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31. 1. SYSTEM SOFTWARE
Thesystemsoftwareisacollectionofprogramsdesignedto
operate,control,andextendtheprocessingcapabilitiesofthe
computeritself.
Thesesoftwareproductscompriseofprograms
writteninlow-levellanguages,whichinteractwiththe
hardwareataverybasiclevel.Systemsoftwareservesasthe
interfacebetweenthehardwareandtheendusers.
SomeexamplesofsystemsoftwareareOperating
System,Compilers,Interpreter,Assemblers,etc.
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32. OPERATING SYSTEM
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33. OPERATING SYSTEM ARCHITECTURE
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34. FUNCTIONS OF OPERATING SYSTEM
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35. TYPES OF OPERATING SYSTEM
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36. SINGLEUSEROS:Asthenameimplies,thisoperating
systemisdesignedtomanagethecomputersothatoneusercan
effectivelydoonethingatatime.
MULTIUSEROS:Amulti-useroperatingsystem(OS)isa
computersystemthatallowsmultipleusersthatareondifferent
computerstoaccessasinglesystem'sOSresources
simultaneously.
MULTITASKINGOS:Multitasking,isanoperatingsystem,
that allowsausertoperformmorethanone
computertask(suchasthemultipleoperationofanapplication
program)atatime.Theoperatingsystemisabletokeeptrack
ofwhereyouareinthesetasksandgofromonetotheother
withoutlosinginformation.
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MULTIPROCESSING OS:Multiprocessingis
sometimes used torefertotheexecution
ofmultipleconcurrentprocessesinasystem.Aprogramin
executioniscalledprocess.
EMBEDDED OS:EmbeddedOperatingSystemisan
EmbeddedSystem’sOperatingSystem.EmbeddedSystems
areaspeciallydesignedcomputersystemthatessentially
containssoftwareandhardwareforperformingspecific
tasks.MobilePhones,Laptops,Cameras,WashingMachines,
ATMS,andHairStraighteneretcareexamplesofembedded
operatingsytem.

38. REALTIMEOS:Itisusedtocontrolmachinery,industrial
systems,scientificinstruments,taskswheretimedeadlinesmay
beforcedtoexecuteatask.
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39. LANGUAGE PROCESSOR
Wegenerallywriteacomputerprogramusingahigh-level
language.Ahigh-levellanguageisonethatisunderstandable
byus,humans.Thisiscalledsourcecode.
However,acomputerdoesnotunderstand
high-levellanguage.Itonlyunderstandstheprogramwritten
in0'sand1'sinbinary,calledthemachinecode.
Toconvertsourcecodeintomachinecode,weuseeither
acompileroraninterpreter.Compiler,Interpreterareknown
aslanguageprocessor.Bothcompilersandinterpretersare
usedtoconvertaprogramwritteninahigh-levellanguage
intomachinecodeunderstoodbycomputers.However,there
aredifferencesbetweenhowaninterpreterandacompiler
works.
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40. DIFFERENCE BETWEEN COMPILER AND INTERPRETER
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41. APPLICATION SOFTWARE
Applicationsoftwareproductsaredesignedtosatisfya
particularneedofaparticularenvironment.Allsoftware
preparedinthecomputerlabmaycomeunderthecategoryof
Applicationsoftware.
ExamplesofApplicationsoftwarearethefollowing−
❑PayrollSoftware
❑StudentRecordSoftware
❑InventoryManagementSoftware
❑IncomeTaxSoftware
❑RailwaysReservationSoftware
❑MicrosoftOfficeSuiteSoftware
❑MicrosoftWord,MicrosoftExcel
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42. UTILITY SOFTWARE
Utilitysoftwareisdesignedtoaidinanalyzing,optimizing,
configuringandmaintainingacomputersystem.Itsupports
thecomputerinfrastructure.Thissoftwarefocusesonhowan
OSfunctionsandthenaccordinglyitdecidesitstrajectoryto
smoothenthefunctioningofthesystem.Software’slike
antiviruses,diskcleanup&managementtools,compression
tools,defragmenters,etcareallutilitytools.Someexamplesof
utilitytoolsare:
K7Antivirus,WinRAR,WinZipetc.
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