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1、程序设计导论sk2007ComputerHardwareComputersareconstructedfromphysicalcomponentsreferredtoashardwareHardwarefacilitatesthestorageandprocessingofdataunderthedirectionofafilesystemComputerhardwaredoesnotstoredatausingthesamesymbolsthathumansdo2BitsandBytesThesmallestandmostbasi
2、cdataiteminacomputerisabitOpenorclosedswitch0or1Thegroupingof8bitstoformalargerunitisreferredtoasabyteCanrepresentanyoneof256distinctpatternsThecollectionsofpatternsconsistingof0sand1susedtorepresentletters,singledigits,andothersinglecharactersarecalledcharactercodesco
3、mputerhardware3Componentscomputerhardware4MainMemoryUnit(RAM)StoresdataandinstructionsassequenceofbytesAprogrammustresideinmainmemoryifitistooperateonthecomputerCombines1ormorebytesintoasingleunit,referredtoasawordConstructedasrandomaccessmemory,orRAMEverysectionofmemo
4、rycanbeaccessedrandomlyasquicklyasanyothersectionVolatile:dataislostwhenpoweristurnedoffSizeisusuallyspecifiedinbytes(MBorGB)computerhardware5CentralProcessingUnit(CPU)Controlunit:directsandmonitorstheoveralloperationofthecomputerKeepstrackofwherethenextinstructionresi
5、desIssuesthesignalsneededtobothreaddatafromandwritedatatootherunitsinthesystemExecutesallinstructionsArithmeticandLogicUnit(ALU):performsallofthecomputations,suchasaddition,subtraction,comparisons,andsoon,CPUsareconstructedasasinglemicrochip,whichisreferredtoasamicropr
6、ocessorcomputerhardware6Input/OutputUnitTheinput/output(I/O)unitprovidesaccesstothecomputer,allowingittoinputandoutputdataItistheinterfacetowhichperipheral(外围的)devices,suchaskeyboards,consolescreens,andprinters,areattachedcomputerhardware7SecondaryStorageUsedaspermanen
7、tstorageforprogramsanddataMagnetictape,magneticdisks,andCD-ROMsDirectaccessstoragedevice(DASD):allowsacomputertoreadorwriteanyonefileorprogramindependentofitspositiononthestoragemediumMagneticharddiskconsistsofrigidplattersthatspintogetheronacommonspindleInitially,them
8、ostcommonmagneticdiskstoragedevicewastheremovablefloppydiskcomputerhardware8MagneticHardDisk扇区柱面道computerhardware9Pro
