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計(jì)算機(jī)英語第二講主講人趙永義2022年8月人工智能學(xué)院河北東方學(xué)院HebeiOrientalUniversity2023/6/2512023/6/252Chapter2ComputerSystemOrganizationLead-inAcomputersystemconsistsofhardwaresystemandsoftwaresystem.Harewareisthematerialfoundationofthecomputer,butwithoutsoftware,hardwarecannotbeinstructedtoprocessdataintoinformation.Hence,hardwareisthebodyofthecomputerandsoftwarethesoul.Inthischapter,wemainlyintroducethecomputerhardwareandsoftwarewillbeillustratedinthefollowingchapter.Computerhardwareistheequipmentinvolvedinthefunctionofacomputerandconsistsofthecomponents2023/6/253Chapter2ComputerSystemOrganizationthatcanbephysicallyhandled.Itisusuallydividedintothreeprimarysubsystems（子系統(tǒng)）:theCPU,thememorysubsystemandtheinput\output(I\O)subsystem.Thesethreepartsareinterconnected（互相聯(lián)系）

bybuses,oftenmadeofgroupsofwires.計(jì)算機(jī)硬件是計(jì)算機(jī)運(yùn)行所需要的設(shè)備,由可被物理操縱的部件組成。這三個(gè)部分通過總線相互連接，經(jīng)常由成組的導(dǎo)線制成。2023/6/254Chapter2ComputerSystemOrganization2.1CPUThecomputer’scentralprocessingunit(CPU)istheelectroniccircuitrythatprovidesthecomputationalabilityandcontrolofcomputer.Internally,theCPUhasthreesections---ALU,ControlUnit,RegisterSet.CPU是計(jì)算機(jī)的運(yùn)算和控制核心。2023/6/255Chapter2ComputerSystemOrganization2.1.1ArithmeticandLogicUnit算術(shù)邏輯運(yùn)算器Asitsnameimplied,thearithmeticandlogicunit(ALU)performtwoclassesofoperations:arithmeticandlogic.Arithmeticoperationsincludeaddition,subtraction,multiplicationanddivision.Anycomputercanbeprogrammedtoperformanyarithmeticoperation.LogicoperationsincludeBooleanlogic:AND,OR,XORandNOT.ThesecanbeusefulbothforcreatingcomplicatedconditionalstatementsandprocessingBooleanlogic.Mostcomputerscanalsoperformcertainlogicoperationsonwords.

2023/6/256Chapter2ComputerSystemOrganizationAstheabovediagramshows,theALUreceivesitsoperandsfromtheregistersetoftheCPUandstoresitsresultsbackintheregisterset.Itperformwhateverarithmeticorlogicoperationsarerequiredtohelpcarryouttheinstructions.大多數(shù)計(jì)算機(jī)還可以對(duì)文字執(zhí)行某些邏輯運(yùn)算。

operands[??p?r?ndz]n.操作數(shù)；運(yùn)算物體；運(yùn)算對(duì)象如上圖所示，ALU從CPU的寄存器組接收其操作數(shù)，并將其結(jié)果存儲(chǔ)回寄存器組。它執(zhí)行幫助執(zhí)行指令所需的任何算術(shù)或邏輯運(yùn)算。2023/6/257Chapter2ComputerSystemOrganization2.1.2ControlUnitThecontrolunit,oftencalledacontrolsystem,isafunctionalunitsupervisingtheoperationoftheentirecomputersystem.Itmakesconnectionsbetweenvariousfunctionalunitsofthecomputersystemandinterpretsinstructionsintheprogrammeonebyone.Thecontrolunitfetchesinstructionsfrommemoryanddeterminestheirtypesordecodesthem.Itthenbreakseachinstructionintoaseriousofcontrolsignalsthatoperatetheotherpartsofthecomputer.Controlsystemsinadvancedcomputersmaychangetheorderofsomeinstructionssoastoimproveperformance.It’snoticeablethatthesequenceofoperationsthatthe2023/6/258Chapter2ComputerSystemOrganizationcontrolunitgoesthroughtoprocessaninstructionisinitselflikeashortcomputerprogram.注意：控制器處理指令的操作順序本身就像一個(gè)短程序。2.1.3RegisterSetTheregistersetstoresintermediatedatausedduringtheexecutionoftheinstructions,whichincludesasetofregistersandabusorothercommunicationmechanism.AregisterisaquicklyaccessiblelocationavailabletoaCPU.Itcanbereadandwrittentomuchmorerapidlythanthemainmemoryarea,whichavoids2023/6/259Chapter2ComputerSystemOrganizationhavingtoaccessmainmemoryeverytimedataisneeded.Sincedataisconsistentlybeingworkedon,reducingneedtoaccessmainmemorygreatlyincreasesthecomputer’sspeed.Almostallcomputersloaddatafromalargermemoryintoregisterwhereitisusedforarithmeticoperationsandismanipulatedortestedbyinstructions.Manipulateddataisthenoftenstoredbacktomainmemory.execution[?eks??kju??n][U](formal)實(shí)行；執(zhí)行；實(shí)施performingaduty,orputtingaplanintoaction2023/6/2510Chapter2ComputerSystemOrganization2.2MemorysubsystemMemory,alsoknownasainternalmemoryormainmemory,referstothecomputerchipsthatstoreinformationforquickretrievalbytheCPU.Acomputer’smemorycanbeviewedasalistofcellsintowhichnumberscanbeplacedorread.Inalmostallmoderncomputers,eachmemorycellissetuptostorebinarynumbersingroupsofeightbits,calledabyte.Acomputercanstoreanykindofinformationinmemoryaslongasitcanbesomehowrepresentedinnumericalform.Moderncomputershavebillionsoreventrillionsofbytesofmemory.2023/6/2511Chapter2ComputerSystemOrganizationAcomputer’smainmemorycomesintwoprincipalvarieties:radomacccessmemory(RAM)andread-onlymemory(ROM).存儲(chǔ)器，也稱為內(nèi)部存儲(chǔ)器或主存儲(chǔ)器，是指存儲(chǔ)信息以供CPU快速檢索的計(jì)算機(jī)芯片。計(jì)算機(jī)的內(nèi)存可被視為一系列的單元，可以在單元中存取數(shù)字。在幾乎所有現(xiàn)代計(jì)算機(jī)中，每個(gè)內(nèi)存單元都被設(shè)置為存儲(chǔ)八位為一組（稱為字節(jié)）的二進(jìn)制數(shù)。只要信息能以數(shù)字形式表示，計(jì)算機(jī)就可以在存儲(chǔ)器中存儲(chǔ)任何類型的信息。現(xiàn)代計(jì)算機(jī)擁有數(shù)十億甚至萬億字節(jié)的內(nèi)存。計(jì)算機(jī)的主存儲(chǔ)器有兩種主要類型：隨機(jī)存取存儲(chǔ)器（RAM）和只讀存儲(chǔ)器（ROM）。2023/6/2512Chapter2ComputerSystemOrganization2.2.1RAMRAMisusedtostoretheinformationandinstructionsthatoperatethecomputer’sprograms.ItisessentialtoacomputerbecauseitprovidesrapidlyaccessiblecircuitrywheretheCPUcanrunprogramsandprocessdata.AllthedatatypedintothecomputergoesdirectlytoRAM.Thecomputer’sRAMsizelargelydetermineshowmanyprogramsmayrunsimultaneouslywithoutperformancedegradation.Ifthecomputerhastoolittlememory,complicatedprogramswillrunslowlyorwon’trunatall.2023/6/2513Chapter2ComputerSystemOrganizationRAMisalsoknownasvolatilememorybecausetheinformationwithinthecomputerchipsiserasedassoonasthecomputerisswitchedoff.Tokeepdatapermanently,itisnecessarytocopythedatatoasecondarystoragedevicesuchasadisk.隨機(jī)存儲(chǔ)器用于存儲(chǔ)操作計(jì)算機(jī)程序的信息和指令，它對(duì)計(jì)算機(jī)至關(guān)重要，因?yàn)樗峁┝丝焖僭L問的電路，CPU可以在RAM中運(yùn)行程序和處理數(shù)據(jù),輸入計(jì)算機(jī)的所有數(shù)據(jù)直接進(jìn)入RAM。計(jì)算機(jī)的RAM大小在很大程度上決定了有多少程序可以同時(shí)運(yùn)行而不會(huì)降低計(jì)算機(jī)的操作性能。如果計(jì)算機(jī)內(nèi)存太小，復(fù)雜的程序?qū)⑦\(yùn)行緩慢或根本無法運(yùn)行。RAM也稱作是易失存儲(chǔ)器，因?yàn)楫?dāng)計(jì)算機(jī)的電源關(guān)閉時(shí)，計(jì)算機(jī)芯片中的信息隨著丟失。要永久保存數(shù)據(jù)，必須將數(shù)據(jù)復(fù)制到輔助存儲(chǔ)設(shè)備上（如磁盤）。

2023/6/2514Chapter2ComputerSystemOrganizationRAMcanbefurthercategorizedintoastaticrandomaccessmemory(SRAM)andadynamicrandomaccessmemory(DRAM).InSRAM,theword“static”indicatesthatthememoryretainsitscontentsaslongaspowerisbeingsupplied.However,dataislostwhenthepowergetsdownduetoitsvolatilenature.SRAMchipsuseamatrixof6-transistors.RAM可進(jìn)一步分類為靜態(tài)隨機(jī)存取存儲(chǔ)器（SRAM）和動(dòng)態(tài)隨機(jī)存取存儲(chǔ)器（DRAM）。在SRAM中，“靜態(tài)”一詞表示只要電源接通，內(nèi)存就會(huì)保持其內(nèi)容。然而，由于其易失性，當(dāng)功率下降時(shí)，數(shù)據(jù)會(huì)丟失。SRAM芯片使用6晶體管矩陣。2023/6/2515Chapter2ComputerSystemOrganizationDRAM,unlikeSRAM,mustbeperiodically

refreshedinordertomaintainthedata.Thisisdonebyplacingthememoryonarefreshcircuitthatrewritesthedataseveralhundredtimespersecond.AllDRAMsaremadeupofmemorycellswhicharecomposedofonecapacitorandonetransistor.與SRAM不同，DRAM必須定期刷新以保存數(shù)據(jù)。這是通過將存儲(chǔ)器置于刷新電路上實(shí)現(xiàn)的，刷新電路每秒重寫數(shù)據(jù)幾百次。所有DRAM都由存儲(chǔ)單元組成，存儲(chǔ)單元由一個(gè)電容器和一個(gè)晶體管組成。2023/6/2516Chapter2ComputerSystemOrganizationBecauseoftheextraspaceinthematrix,SRAMusesmorechipsthanDRAMforthesameamountofstoragespace,thusmakingthemanufacturingcostshigher.SoSRAMisusedascachememoryandhasveryfastaccess.Incontrast,beingcheaperandsmaller,DRAMisusedformostsystemmemory.由于矩陣中的額外空間，SRAM在相同的存儲(chǔ)空間下使用比DRAM更多的芯片，所以制造成本更高。因此，SRAM被用作高速緩沖存儲(chǔ)器，具有非?？斓脑L問速度。相比之下，由于價(jià)格更便宜和體積更小，DRAM用于大多數(shù)系統(tǒng)內(nèi)存。2023/6/2517Chapter2ComputerSystemOrganization2.2.2ROMAsitsnameimplies,datastoredinROMcannotberewrittenbutreadonly.Itcontainscriticalinformationandsoftwarethatmustbepermanentlyavailableforcomputeroperation.Itisalsoknownasnonvolatilememorybecausethememorychipsdonotlosetheirinformationwhenthecomputerpowerisoff.Whenthecomputeristurnedon,thepermanentsoftwareinROMbootsthecomputer.顧名思義，存儲(chǔ)在ROM中的數(shù)據(jù)不能重寫，只能讀取。它包含必須永久性可供計(jì)算機(jī)操作使用的關(guān)鍵信息和軟件。ROM也稱為非易失性存儲(chǔ)器，因?yàn)楫?dāng)計(jì)算機(jī)的電源關(guān)閉時(shí)，存儲(chǔ)芯片中的信息不會(huì)丟失。當(dāng)計(jì)算機(jī)打開時(shí)，ROM中的永久軟件啟動(dòng)計(jì)算機(jī)。2023/6/2518Chapter2ComputerSystemOrganizationROMchipscanbefurthercategorizedintoprogrammablereadonlymemory(PROM),erasableandprogrammablereadonlymemory(EPROM),andelectricallyerasableandprogrammablereadonlymemory(EEPROM),whicharedifferentiatedbyhowandhowoftentheycanbeprogrammed.PROMcanbemodifiedonlyoncebyauser.TheuserbuysablankPROMandentersthedesiredcontentsusingaPROMprogram.InsidethePROMchiptherearesmallfuseswhichareburntopenduringprogramming.Itcanbeprogrammedonlyonceandisnoterasable.ROM芯片可進(jìn)一步分為可編程只讀存儲(chǔ)器（PROM）、可擦除可編程只讀內(nèi)存（EPROM）以及電可擦除可編程只讀存儲(chǔ)器（EEPROM)，它們的不同之處在于可編程的方式和頻率。PROM只能由用戶修改一次，用戶購買空白PROM并使用PROM程序輸入所需內(nèi)容。PROM芯片內(nèi)部有一些小保險(xiǎn)絲（也稱為熔絲），它們在編程過程中燒斷。它只能編程一次，并且不可擦除。2023/6/2519Chapter2ComputerSystemOrganizationEPROMcanbeerasedbyexposingittoultravioletlightforadurationofuptofortyminutes.Usually,anEPROMeraserachievesthisfunction.Duringprogramminganelectricalchargeistrappedinaninsulatedgateregion.Thechargeisretainedformorethantenyearsbecausethechargehasnoleakagepath.Forerasingthischarge,ultravioletlightispassedthroughaquartzcrystalwindow.Thisexposuretoultravioletlightdissipatesthecharge.EPROM可以通過將其暴露在紫外光下長達(dá)40分鐘來擦除,通常，EPROM擦除器實(shí)現(xiàn)此功能。在編程期間，電荷被捕獲在絕緣柵極區(qū)域中,由于電荷沒有泄漏路徑，因此電荷可以保留十年以上。為了消除這種電荷，紫外光通過石英晶體窗口,這種對(duì)紫外光的暴露會(huì)消散電荷。2023/6/2520Chapter2ComputerSystemOrganizationEEPROMisprogrammedanderasedelectrically.Itcanbeerasedandreprogrammedabouttenthousandtimes.Botherasingandprogrammingtakeabout4to10ms(milliseconds).InEEPROM,anylocationcanbeselectivelyerasedandprogrammed.EEPROMscanbeerasedonebyteatatime,ratherthanerasingtheentirechip.Hence,theprocessofprogrammingisflexiblebutslow.EEPROM以電氣方式編程和擦除,它可以被擦除和重新編程大約一萬次。擦除和編程都需要大約4至10毫秒。在EEPROM中，可以選擇性地擦除和編程任何位置。EEPROM可以一次擦除一個(gè)字節(jié)，而不是擦除整個(gè)芯片。因此，編程過程靈活但緩慢。2023/6/2521Chapter2ComputerSystemOrganization2.3I\OSubsystemI\Oisthemeansbywhichacomputerreceivesinformationfromtheoutsideworldandsendsresultsback.Devicesthatprovideinputoroutputtothecomputerarecalledperipherals.Onatypicalpersonalcomputer,peripheralsincludeinputslikethekeyboardandmouse,andoutputssuchasthemonitorandprinter.Storagedevicessuchasharddisks,floppydisksandcompactdisksservebothinputsandoutputs.ComputernetworkisanotherformofI\O.I/O是計(jì)算機(jī)從外部世界接收信息并返回結(jié)果的手段。向計(jì)算機(jī)提供輸入或輸出的設(shè)備稱為外圍設(shè)備,在典型的個(gè)人計(jì)算機(jī)上，外圍設(shè)備包括鍵盤和鼠標(biāo)等輸入，以及顯示器和打印機(jī)等輸出。硬盤、軟盤和光盤等存儲(chǔ)設(shè)備既可作為輸入，也可作為輸出。計(jì)機(jī)網(wǎng)絡(luò)是另一種I/O形式。2023/6/2522Chapter2ComputerSystemOrganizationInput----keyboard,mouse,scanner,modemandmicrophone.Output----monitor,printer,audiooutputdevices(speakersandheadsets)2.3.3OtherI\ODevices1.DiskDriveStoragehardwarealsocanberegardedasinputandoutputdevices.Differentfromthemainmemory,itprovidespermanentstorageofinformationandprogramsforretrievalbythecomputer.Onecommonly