Part-2-Unit-01-Computer-Technologies

Unit1ComputerTechnologiesIntroductionCentralProcessingUnit(CPU)ComputerProgrammingLanguagesComputerProcessInterfacingComputerNetworkStructuresIntroductionThecentralandessentialingredientofCAD/CAMisthedigitalcomputer.Itsinherentspeedandstoragecapacityhavemadeitpossibletoachievetheadvancesinimageprocessing,real-timeprocesscontrol,andamultitudeofotherimportantfunctionsthataresimplytoocomplexandtimeconsumingtoperformmanually.TounderstandCAD/CAM,itisimportanttobefamiliarwiththeconceptsandtechnologyofthedigitalcomputer.IntroductionThemoderndigitalcomputerisanelectronicmachinethatcanperformmathematicalandlogicalcalculationsanddataprocessingfunctionsinaccordancewithapredeterminedprogramofinstructions.Thecomputeritselfisreferredtoashardware,whereasthevariousprogramsarereferredtoassoftware.IntroductionTherearethreebasichardwarecomponentsofageneral-purposedigitalcomputer:(l)Centralprocessingunit(CPU)(2)Memory(3)Input/output(I/O)sectionIntroductionTherelationshipofthesethreecomponentsisillustratedinFig.1.1.Thecentralprocessingunitisoftenconsideredtoconsistoftwosubsections:acontrolunitandanarithmetic-logicunit(ALU).Thecontrolunitcoordinatestheoperationsofalltheothercomponents.IntroductionItcontrolstheinputandoutputofinformationbetweenthecomputerandtheoutsideworldthroughtheI/Osection,synchronizesthetransferofsignalsbetweenthevarioussectionsofthecomputer,andcommandstheothersectionsintheperformanceoftheirfunctions.IntroductionThearithmetic-logicunitcarriesoutthearithmeticandlogicmanipulationsofdata.Itadds,subtracts,multiplies,divides,andcomparesnumbersaccordingtoprogrammedinstructions.Thememoryofthecomputeristhestorageunit.ThedatastoredinthissectionarearrangedintheformofwordswhichcanbeconvenientlytransferredtotheALUorI/Osectionforprocessing.IntroductionFinally,theinput/outputprovidesthemeansforthecomputertocommunicatewiththeexternalworld.Thiscommunicationisaccomplishedthroughperipheralequipmentsuchasreaders,printers,andprocessinterfacedevices.Thecomputermayalsobeconnectedtoexternalstorageunits(e.g.,tapes,disks,etc.)throughtheI/Osectionofthecomputer.IntroductionThesoftwareconsistsoftheprogramsandinstructionsstoredinmemoryandinexternalstorageunits.Itisthesoftwarethatassignstothecomputerthevariousfunctionswhichtheuserdesiresthesystemtoaccomplish.Theusefulnessofthecomputerliesinitsabilitytoexecutetheinstructionsquicklyandaccurately.IntroductionBecausethecontentsofthecomputer’smemorycanbeeasilychanged,andthereforedifferentprogramscanbeplacedintomemory,thedigitalcomputercanbeusedforawidevarietyofapplications.IntroductionRegardlessoftheapplication,thecomputerexecutestheprogramthroughitsabilitytomanipulatedataandnumbersintheirmostelementaryform.Thedataandnumbersarerepresentedinthecomputerbyelectricalsignalswhichcantakeoneoftwoalternativestates.IntroductionThisformofrepresentationiscalledthebinarysystem.Themorefamiliardecimalnumbersystemandawholehostofsoftwarelanguagescanutilizethebinarysystemtopermitcommunicationbetweencomputersandhumanbeings.CentralProcessingUnit(CPU)Thecentralprocessingunit(CPU)regulatestheoperationofallsystemcomponentsandperformsthearithmeticandlogicaloperationsonthedata.Toaccomplishthesefunctions,theCPUconsistsoftwooperatingunits:(1)Controlunit(2)Arithmetic-logicunit(ALU)CentralProcessingUnit(CPU)Thecontrolunitcoordinatesthevariousoperationsspecifiedbytheprograminstructions.Theseoperationsincludereceivingdatawhichenterthecomputeranddecidinghowandwhenthedatashouldbeprocessed.CentralProcessingUnit(CPU)Thecontrolunitdirectstheoperationofthearithmetic-logicunit.ItsendsdatatotheALUandtellstheALUwhatfunctionstoperformonthedataandwheretostoretheresults.Thecapabilityofthecontrolunittoaccomplishtheseoperationsisprovidedbyasetofinstructionscalledanexecutiveprogramwhichisstoredinmemory.CentralProcessingUnit(CPU)Thearithmeticandlogicunitperformsoperationssuchasaddition,subtractions,andcomparisons.Theseoperationsarecarriedoutondatainbinaryform.Thelogicsectioncanalsobeusedtoalterthesequenceinwhichinstructionsareexecutedwhencertainconditionsareindicatedandtoperformotherfunctions,suchaseditingandmaskingdataforarithmeticoperations.CentralProcessingUnit(CPU)Boththecontrolunitandthearithmetic-logicunitperformtheirfunctionsbyutilizingregisters.Computerregistersaresmallmemorydevicesthatcanreceive,hold,andtransferdata.Eachregisterconsistsofbinarycellstoholdbitsofdata.Thenumberofbitsintheregisterestablishesthewordlengththecomputeriscapableofhandling.Thenumberofbitsperwordcanbeasfewas4(earlymicrocomputers)orasmanyas64(largescientificcomputers).ComputerProgrammingLanguagesThebinarynumbersystemcouldbeusedtorepresentanydecimalnumber,alphabeticletter,orothercommonsymbol.Dataandinstructionsarecommunicatedtothecomputerintheformofbinarywords.ComputerProgrammingLanguagesInexecutingaprogram,thecomputerinterpretstheconfigurationofbitsasaninstructiontoperformelectronicoperationssuchasadd,subtract,loadintomemory,andsoforth.Thesequenceofthesebinary-codedinstructionsdefinesthesetofcalculationsanddatamanipulationsbywhichthecomputerexecutesthep