Chapter5ComputerSection2MicroprocessorandMemory

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NewWordsandExpressions

Exercises

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AdditionorOmissionofChinesewordsSection2MicroprocessorandMemoryMicroprocessorAmicroprocessor(sometimessimplyreferredtoasa"processor")isanintegratedcircuitdesignedtoprocessinstructions.Itisthemostimportantcomponentofacomputer,andusuallythemostexpensivesinglecomponent,containingas50millionminiaturizedelectroniccomponents.Theminiaturizedcircuitryinamicroprocessorisgroupedintoimportantfunctionalareas,suchastheALUandthecontrolunit.Section2MicroprocessorandMemoryTheALU(arithmeticlogicunit)performsarithmeticoperations,suchasadditionandsubtraction.Italsoperformslogicaloperations,suchascomparingtwonumberstoseeiftheyarethesame.TheALUusesregisterstoholddatathatisbeingprocessed.Themicroprocessor'scontrolunitfetcheseachinstruction.ThecomputerloadsdataintotheALU'sregisters.Finally,thecontrolunitgivestheALUthegreenlighttobeginprocessing.Section2MicroprocessorandMemoryTheperformanceofamicroprocessorisaffectedbyseveralfactors,includingclockspeed,wordsize,cachesize,instructionset,andprocessingtechniques.Thespeedspecificationsthatyouseeinacomputeradindicatethespeedofthemicroprocessorclock—atimingdevicethatsetsthepaceforexecutinginstructions.Mostcomputeradsspecifythespeedofamicroprocessorinmegahertz(MHz)orgigahertz(GHz).Megahertzmeansamillioncyclespersecond.Gigahertzmeansabillioncyclespersecond.Section2MicroprocessorandMemoryAcycleisthesmallestunitoftimeinamicroprocessor'suniverse.Everyactionthataprocessorperformsismeasuredbythesecycles.Itisimportant,however,tounderstandthattheclockspeedisnotequaltothenumberofinstructionsthataprocessorcanexecuteinonesecond.Inmanycomputers,someinstructionsoccurwithinonecycle,butotherinstructionsmightrequiremultiplecycles.Someprocessorscanevenexecuteseveralinstructionsinasingleclockcycle.Section2MicroprocessorandMemoryWordsizereferstothenumberofbitsthatamicroprocessorcanmanipulateatonetime.WordsizeisbasedonthesizeoftheregistersintheALU,andthecapacityofcircuitsthatleadtothoseregisters.Amicroprocessorwithan8-bitwordsize,forexample,has8-bitregisters,processeseightbitsatatime,andisreferredtoasan"8-bitprocessor."Processorswithalargerwordsizecanprocessmoredataduringeachprocessorcycle,afactorthatleadstoincreasedcomputerperformance.Today'spersonalcomputerstypicallycontain32-bitor64-bitprocessors.Section2MicroprocessorandMemoryCacheissometimescalled"RAMcache"or"cachememory."Itisspecialhigh-speedmemorythatallowsamicroprocessortoaccessdatamorerapidlythanfrommemorylocatedelsewhereonthemotherboard.Somecomputeradsspecifycachetypeandcapacity.ALevel1cache(L1)isbuiltintotheprocessorchip,whereasaLevel2cache(L2)islocatedonaseparatechipandtakesalittlemoretimetogetdatatotheprocessor.Cachecapacityisusuallymeasuredinkilobytes.Section2MicroprocessorandMemoryAschipdesignersdevelopedvariousinstructionsetsformicroprocessors,theytendedtoaddincreasinglymorecomplexinstructionsthateachrequiredseveralclockcyclesforexecution.AmicroprocessorwithsuchaninstructionsetusesCISC(complexinstructionsetcomputer)technology.AmicroprocessorwithalimitedsetofsimpleinstructionsusesRISC(reducedinstructionsetcomputer)technology.ARISCprocessorperformsmostinstructionsfasterthanaCISCprocessor.Itmight,however,requiremoreoftheseSection2MicroprocessorandMemorysimpleinstructionstocompleteataskthanaCISCprocessorrequiresforthesametask.Someprocessorsexecuteinstructions"serially"—thatis,oneinstructionatatime.Withserialprocessing,theprocessormustcompleteallofthestepsintheinstructioncyclebeforeitbeginstoexecutethenextinstruction.However,usingatechnologycalledpipelining,aprocessorcanbeginexecutinganinstructionbeforeitcompletesthepreviousinstruction.Manyoftoday'smicroprocessorsalsoperformparallelprocessing,inwhichmultipleinstructionsareexecutedattheSection2MicroprocessorandMemorysametime.Pipeliningandparallelprocessingenhanceprocessorperformance.RAM(RandomAccessMemory)RAMisatemporaryholdingareafordata,applicationprograminstructions,andtheoperatingsystem.Inapersonalcomputer,RAMisusuallyseveralchipsorsmallcircuitboardsthatplugintothemotherboardwithinthecomputer'ssystemunit.Section2MicroprocessorandMemoryRAMisthe"waitingroom"forthecomputer'sprocessor.Itholdsrawdatathatiswaitingtobeprocessed,aswellastheprograminstructionsforprocessingthatdata.Inaddition,RAMholdstheresultsofprocessinguntiltheycanbestoredmorepermanentlyondiskortape,andoperatingsysteminstructionsthatcontrolthebasicfunctionsofacomputersystem.TheseinstructionsareloadedintoRAMeverytimeyoustartyourcomputer,andtheyremainthereuntilyouturnoffyourcomputer.Section2MicroprocessorandMemoryInRAM,microscopicelectronicpartscalledcapacitorsholdthebitsthatrepresentdata.Youcanvisualizethecapacitorsasmicroscopiclightsthatcanbeturnedonoroff.Achargedcapacitoris"turnedon"andrepresentsa"1"bit.Adischargedcapacitoris"turnedoff"andrepresentsa"0"bit.Eachbankofcapacitorsholdseightbits—onebyte—ofdata.ARAMaddressoneachbankhelpsthecomputerlocatedata,asneeded,forprocessing.Section2MicroprocessorandMemoryThecontentsofRAMcanbechangedjustbychangingthechargeofthecapacitors.Unlikediskstorage,mostRAMisvolatile,whichmeansthatitrequireselectricalpowertoholddata.Ifthecomputeristurnedoff,orifthepowergoesout,alldatastoredinRAMinstantlyandpermanentlydisappears.ThecapacityofRAMisusuallyexpressedinmegabytes(MB).Today'spersonalcomputerstypicallyfeaturebetween64and512MBofRAM.TheamountofRAMneededbyyourcomputerSection2MicroprocessorandMemorydependsonthesoftwarethatyouuse.RAMrequirementsareroutinelyspecifiedontheoutsideofasoftwarepackage.IfitturnsoutthatyouneedmoreRAM,youcanpurchaseandinstalladditionalmemoryuptothelimitsetbythecomputermanufacturer.Today'spersonalcomputeroperatingsystemsarequiteadeptatallocatingRAMspacetomultipleprograms.Ifaprogramexceedstheallocatedspace,theoperatingsystemusesanareaoftheharddisk,calledvirtualmemory,tostorepartsofaprogramordatafileuntiltheyareneeded.Section2MicroprocessorandMemoryByselectivelyexchangingthedatainRAMwiththedatainvirtualmemory,yourcomputereffectivelygainsalmostunlimitedmemorycapacity.Toomuchdependenceonvirtualmemorycanhaveanegativeaffectonyourcomputer'sperformance,however,becausegettingdatafromamechanicaldevice,suchasaharddisk,ismuchslowerthangettingdatafromanelectronicdevice,suchasRAM.Section2MicroprocessorandMemoryRAMcomponentsvaryinspeed,technology,andconfiguration.RAMspeedisoftenexpressedinnanoseconds(ns).Onenanosecondis1billionthofasecond.Withnanoseconds,lowernumbersarebetterbecauseitmeansthattheRAMcircuitrycanreactfastertoupdatethedatathatitholds.RAMspeedcanalsobeexpressedinMHz(millionofcyclespersecond)justtheoppositeofnanoseconds,higherMHzratingsmeanfasterspeeds.Section2MicroprocessorandMemoryROM(Read-OnlyMemory)ROMisatypeofmemorycircuitrythatholdsthecomputer'sstartuproutine.ROMishousedinasingleintegratedcircuit—usuallyafairlylarge,caterpillar-likeDIPpackage—whichispluggedintothemotherboard.WhereasRAMistemporaryandvolatile,ROMispermanentandnon-volatile.ROMcircuitryholds"hard-wired"instructionsthatremaininplaceevenwhenthecomputerpoweristurnedoff.TheinstructionsinROMarepermanent,andtheonlywaytochangethemistoreplacetheROMchip.Section2MicroprocessorandMemoryInapersonalcomputer,ROMcontainsasmallsetofinstructionscalledtheROMBIOS(basicinput/outputsystem).Theseinstructionstellthecomputerhowtoaccesstheharddisk,findtheoperatingsystem,andloaditintoRAM.Oncetheoperatingsystemisloaded,thecomputercanunderstandyourinput,displayoutput,runsoftware,andaccessyourdata.Section2MicroprocessorandMemoryCMOSMEMORYInordertooperatecorrectly,acomputermusthavesomebasicinformationaboutstorage,memory,anddisplayconfigurations.RAMgoesblankwhenthecomputerpoweristurnedoff,soconfigurationinformationcannotbestoredthere.ROMwouldnotbeagoodplaceforthisinformationeitherbecauseitholdsdataonapermanentbasis.If,forexample,yourcomputerstoredthememorysizeinROM,youcouldneveraddmorememory—well,youmightbeabletoaddit,butyoucouldn'tchangetheSection2MicroprocessorandMemorysizespecificationinROM.Tostoresomebasicsysteminformation,yourcomputerneedsatypeofmemorythat'smorepermanentthanRAM,butlesspermanentthanROM.CMOSisjusttheticket.CMOS(complementarymetaloxidesemiconductormemory)isatypeofchipthatrequiresverylittlepowertoholddata.Itcanbepoweredbyasmall,rechargeablebatterythat'sintegratedintothemotherboard.ThebatterytricklespowertotheCMOSchipsothatitcanretainvitaldataaboutyourcomputersystemconfigurationevenwhenyourcomputeristurnedoff.WhenyouSection2MicroprocessorandMemorychangetheconfigurationofyourcomputersystem—byaddingRAM,forexample—thedatainCMOSmustbeupdated.Someoperatingsystemsrecognizesuchchangesandautomaticallyperformtheupdate.YoucanmanuallychangeCMOSsettingsbyrunningtheCMOSsetupprogram.ReturnNewWordsandExpressionsminiaturized a.小型的，小型化的ALU(arithmeticlogicunit)

算術(shù)邏輯單元controlunit

控制單元register n.寄存器cycle n.周期clockcycle

時(shí)鐘周期wordsize 字長cache n.高速患緩沖存儲(chǔ)器NewWordsandExpressionsinstructionset

指令集megahertz n.兆赫，兆赫茲gigahertz n.吉赫，吉赫茲motherboard n.母板,主板chip n.芯片，晶片，組件CISC(complexinstructionsetcomputer)

復(fù)雜指令集計(jì)算機(jī)RISC(reducedinstructionsetcomputer)

簡化指令集合計(jì)算機(jī)NewWordsandExpressionsserially ad.串行地serialprocessing

串行處理parallelprocessing

并行處理pipelining a.流水線的RAM(RandomAccessMemory) 隨機(jī)存儲(chǔ)器operatingsystem

操作系統(tǒng)plug v.插入，插上；n.插頭，插入物microscopic a.微觀的，細(xì)微的，顯微（鏡）的，顯微的NewWordsandExpressionscharge v.充電，帶電，起電；n.電荷，充電discharge v.放電bit n.位byte n.字節(jié)volatile a.易失的，揮發(fā)的，易揮發(fā)的，易變的，短暫的megabytes(MB)

兆字節(jié)softwarepackage

軟件包install v.安裝NewWordsandExpressionsvirtualmemory

虛擬存儲(chǔ)器nanosecond

納秒SDRAM(synchronousdynamicRAM)

同步動(dòng)態(tài)RAMROM(Read-OnlyMemory)

只讀存儲(chǔ)器startup n.起動(dòng)caterpillar-like a.履帶式的DIP①=doublein-linepackage

雙列直插式組件②=dualin-linepackage

雙列式封裝NewWordsandExpressionsBIOS(basicinput/outputsystem)

基本輸入輸出系統(tǒng)CMOS(complementarymetaloxidesemiconductormemory)

rechargeablebattery

充電電池setup 安裝update v.更新，修改，校正ReturnAdditionorOmissionofWords

1.動(dòng)詞的省略

英語謂語必須用動(dòng)詞，而漢語不僅可以用動(dòng)詞作謂語，還可以用其他詞類作為謂語。因此，翻譯時(shí)往往可以省略原文中的謂語動(dòng)詞。(1)Thewiregetshot,forthecurrentbecomestoogreat.

電線發(fā)熱，因?yàn)殡娏魈蟆?2)Thischapterprovidesabriefreviewofapplicabletheoryforcomputer.

本章簡單回顧一下計(jì)算機(jī)的應(yīng)用理論。AdditionorOmissionofWords

1.動(dòng)詞的省略(3)Thisdiodeproducesaboutninetimesmoreradiantpowerthanthatone.

這只二極管的輻射功率比那只大九倍左右。

AdditionorOmissionofWords2.引導(dǎo)詞的省略

英語中的兩個(gè)引導(dǎo)詞“it”和“there”，翻譯時(shí)可以省略(1)Theinventionofradiohasmadeitpossibleformankindtocommunicationwitheachotheroveralongdistance.

無線電的發(fā)明使人類有可能進(jìn)行遠(yuǎn)距離通訊。(2)Thereexistneitherperfectinsulatorsnorperfectconductors.

既沒有理想的絕緣體，也沒有理想的導(dǎo)體。AdditionorOmissionofWords2.引導(dǎo)詞的省略(3)

Itisdemonstratedthatittakesayearfortheearthtogoaroundthesun.

已經(jīng)證實(shí)，地球繞太陽轉(zhuǎn)一周需要一年的時(shí)間。AdditionorOmissionofWords3.同義詞或近義詞的省略

在英文專業(yè)文獻(xiàn)中，為了表達(dá)確切，常對(duì)同一事物、同一概念使用不同詞匯來描述。但在漢語中，這種不同詞匯的翻譯往往相同。因此在翻譯時(shí)可將這類同義詞省略。(1)Semiconductordeviceshavenofilamentorheaters,hencetheyrequirenoheatingpowerorwarmeduptime.

半導(dǎo)體器件沒有燈絲，因而不需加熱功率或加熱時(shí)間。AdditionorOmissionofWords3.同義詞或近義詞的省略(2)Themechanicalenergycanbechangedbackintoelectricalenergybymeansofageneratorordynamo.

利用發(fā)電機(jī)可以把機(jī)械能轉(zhuǎn)變成電能。(3)Technologyistheapplicationofscientificmethodandknowledgetoindustrytosatisfyourmaterialneedsandwants.

技術(shù)就是在工業(yè)上應(yīng)用科學(xué)方法和科學(xué)知識(shí)以滿足我們物質(zhì)上的需求。ReturnExercisesI.Choosethebestanswerintotheblank

1.Logicaloperationsareperformedin

ofamicroprocessor.A.thecontrolunit B.theALU C.theregisters D.thestoredarea2.The16-bitprocessorcanprocess

atatime.A.eightbits B.sixteenbits C.thirty-twobits D.sixty-fourbitsExercisesI.Choosethebestanswerintotheblank

3.Amicroprocessoraccessesdatafromcachememory

frommemorylocatedelsewhereonthemotherboard.A.morerapidlythan B.moreslowlythanC.asrapidlyas D.asslowlyas4.DatastoredinRAM

whenthepowerofthecomputeristurnedoff.A.isheldpermanently B.permanentlydisappearsC.isheldtemporarily D.temporarilydisappearsExercisesI.Choosethebestanswerintotheblank

5.Thebasicinformationaboutstorage,memory,anddisplayconfigurationsinacomputerisstoredin

.A.RAM B.ROM C.CMOS D.EPROMExercisesII.Answerthefollowingq