《电子信息工程专业英语导论》课件PART_2_unit5.ppt

1 PART2ModernElectronicsDevices 2 UNIT5Thebasiccomponentsofcomputersystem 3 NewwordsandTechnicalTermsmemoryprocessorperformancelocationsignalinstructionbussemiconductorflip flopchiptransistorbinarycentralprocessingunit CPU integratedcircuit IC input output I O metal oxidesemiconductor MOS readrandommemory RAM onlyreadmemory ROM 4 TextThebasiccomponentsthatmakeupacomputersysteminclude theCPUmemory I O andthebusthatconnectsthesecomponentstogether JohnVonNeumann apioneerincomputerdesign gavethearchitectureofmostcomputersinusetoday AtypicalVonNeumannsystemhasthreemajorparts thecentralprocessingunit orCPU memory andinput output orI O 5 Howasystemdesignsthesepartsimpactsthesystemperformance InVNAmachines likethe80 x86family theCPUiswherealltheactionstakeplace 1 1 在VNA机器体系中 如8086系列 CPU是执行所有事务的地方 在theCPUiswherealltheactionstakeplace中 主语是theCPU wherealltheactionstakeplace是关系副词where引导的从句充当表语 AllcomputationsoccurinsidetheCPU 6 DataandCPUinstructionsresideinmemoryuntilrequiredbytheCPU TotheCPU mostI OdeviceslooklikememorybecausetheCPUcanstoredatatoanoutputdeviceandreaddatafromaninputdevice ThemajordifferencebetweenmemoryandI OdeviceisthatI Odeviceisgenerallyassociatedwithexternaldeviceintheoutsideworld 7 ThesystembusconnectsvariouscomponentsofaVNAmachine The80 x86familyhasthreemajorbusses theaddressbus thedatabus andthecontrolbus Abusisaconnectionofwiresonwhichelectricalsignalspassthroughcomponentsinthesystem Forexample thedatabusmayhaveadifferentimplementationbetweenthe80386andthe8086 8 butbothcarrydataamongtheprocessor I O andmemory The80 x86processorusesthedatabustotransferdataamongthevariouscomponentsinacomputersystem Thesizeofthisbusvarieswidelyinthe80 x86family Indeed thisbusdefinesthe size oftheprocessor Thedatabusonan80 x86familyprocessortransfersinformationbetweenaparticularmemorylocationorI OdeviceandtheCPU 9 Theonlyquestionis WhichmemorylocationorI Odevice Theaddressbusanswersthisquestion TodifferentiatememorylocationandI Odevice auniquememoryaddressisassignedtoeachmemoryelementandI Odevice WhenthesoftwarewantstoaccesscertainmemorylocationorI Odevice itplacesthecorrespondingaddressontheaddressbus 10 CircuitryassociatedwiththememoryorI OrecognizesthisaddressandinstructsthememoryorI Odevicetoreadthedatafromorplacedataonthedatabus 2 与存储器或输入输出相关的电路能够识别地址 并能指使存储器或输入输出设备从数据总线读取数据或存取数据到数据总线 本句的主语是Circuitry and前后是并列关系 AssociatedwiththememoryorI O用于修饰circuitry readthedatafromorplacedataonthedatabus等于readthedatafromthedatabusorplacedataonthedatabus 11 Thecontrolbusisacollectionofsignalsthatcontrolshowtheprocessorcommunicateswiththerestofthesystem 3 3 控制总线是控制处理器与系统其他部分通信的信号枢纽 thatcontrolshowtheprocessorcommunicateswiththerestofthesystem是定语从句 修饰主语thecontrolbus 在这个从句中 又包含了how引导的从句作为controls的宾语 12 Considerthedatabusforamoment TheCPUsendsdatatomemoryandreceivesdatafrommemoryonthedatabus Thispromptsthequestion Isitsendingorreceiving Therearetwolinesonthecontrolbus readlineandwriteline whichspecifythedirectionofdataflow 4 Othersignalsincludesystemclocks interruptlines statuslines andsoon 4 其他信号包括系统时钟 中断信号 状态信号等 13 Theexactstructureofcontrolbusvariesamongprocessorsinthe80 x86family However somecontrollinesarecommontoallprocessorsandareworthyabriefmention Thereadlineandwritelinecontrolthedirectionofdataonthedatabus 14 Whenbothcontainlogic1 theCPUandmemory I Odonotcommunicatewithoneanother Ifthereadlineislow logic0 theCPUreadsdatafrommemory thatis thesystemtransfersdatafrommemorytotheCPU 5 5 当读写信号都是逻辑1时 CPU和内存 I O间不能相互通信 如果读信号是逻辑0时 CPU可以读取内存数据 也就是说系统从内存得到数据 15 Ifthewritelineislow thesystemtransfersdatafromtheCPUtomemory Themainmemoryisthecentralstorageunitinacomputersystem Itisarelativelylargeandfastmemoryusedtostoreprogramsanddataduringthecomputeroperation Theprincipaltechnologyusedforthemainmemoryisbasedonsemiconductorintegratedcircuit 16 IntegratedcircuitRAM ReadRandomMemory chipisavailableintwopossibleoperationmodes staticanddynamic ThestaticRAMconsistsessentiallyofinternalflip flopsthatstorethebinaryinformation Thestoredinformationremainsvalidaslongaspowerisappliedtotheunit ThedynamicRAMstoresthebinaryinformationintheformofelectricchargethatisappliedtothecapacitor 17 ThecapacitorisprovidedinsidethechipbyMOStransistor Thestoredchargeonthecapacitortendstodischargewithtimeandrefreshingthedynamicmemorymustperiodicallyrechargethecapacitor ThedynamicRAMoffersreducedpowerconsumptionandlargestoragecapacityinasinglememorychip ThestaticRAMiseasiertouseandhasshorterreadorwrite