计算机系统结构英文课件

Chapter2:

Computer-SystemStructuresComputerSystemOperationI/OStructureStorageStructureStorageHierarchyHardwareProtectionGeneralSystemArchitectureUniprocessorComputer-SystemArchitecturecontrollerControllerAdevicecontrollerisapartofacomputersystemthatmakessenseofthesignalsgoingto,andcomingfromtheCPUprocessor.Eachdevicecontrollerisinchargeofaparticulardevicetype.Devicecontrollersusebinaryanddigitalcodes.Eachdevicecontrollerhasalocalbufferandacommandregister.I/Oisfromthedevicetolocalbufferofcontroller.I/OdevicesandtheCPUcanexecuteconcurrently.DevicecontrollerscommunicatewiththeCPUbycausinganinterrupt.CommonFunctionsofInterruptsInterruptstransferscontroltotheinterruptserviceroutinegenerally,throughtheinterruptvector,whichcontainstheaddressesofalltheserviceroutines.

通常中断通过中断向量把控制传给中断服务程序Interruptarchitecturemustsavetheaddressoftheinterruptedinstruction.Incominginterruptsaredisabledwhileanotherinterruptisbeingprocessedtopreventalostinterrupt.Atrap

isasoftware-generatedinterruptcausedeitherbyanerrororauserrequest.Anoperatingsystemisinterruptdriven.InterruptHandlingTheoperatingsystempreservesthestateoftheCPUbystoringregistersandtheprogramcounter.Determineswhichtypeofinterrupthasoccurred:polling

vectoredinterruptsystemSeparatesegmentsofcodedeterminewhatactionshouldbetakenforeachtypeofinterruptInterruptTimeLineForaSingleProcessDoingOutput(P21)I/OStructure1.Nochannel(IOP):pollingCPU-OrientedCPURAMCCCCDiskDrivePrinterDeviceSystemBus…I/OStructure2.channel(IOP):Memory-OrientedC1IOP1CPURAMIOP2C2C3C4Device1Device2Device3Device4Device5Device6Device7HowtooutputthedatainRAM?ConstructachannelprogramSubmitthechannelprogramtothecorrespondingIOPviaRAMTheIOPexecutesthechannelprogramTheIOPnotifiesCPUbycausinganinterruptuponcompletion

AchannelprogramisasequenceofI/Oinstructionsexecutedbytheinput/outputchannelprocessor(IOP).Thechannelprogramconsistsofoneormorechannelcommandwords.SynchronousI/OAfterI/Ostarts,controlreturnstouserprogramonlyuponI/Ocompletion.

waitinstructionidlestheCPUuntilthenextinterruptwaitloop(contentionformemoryaccess).AtmostoneI/Orequestisoutstandingatatime,nosimultaneousI/Oprocessing.AsynchronousI/OAfterI/Ostarts,controlreturnstouserprogram,withoutwaitingforI/Ocompletion.

Systemcall–requesttotheoperatingsystemtoallowusertowaitforI/Ocompletion.Device-statustablecontainsentryforeachI/Odeviceindicatingitstype,address,andstate.OperatingsystemindexesintoI/Odevicetabletodeterminedevicestatusandtomodifytableentrytoincludeinterrupt.ThemainadvantageofasynchronousI/Oisincreasedsystemefficiency.Device-StatusTableDirectMemoryAccess(DMA)StructureUsedforhigh-speedI/Odevicesabletotransmitinformationatclosetomemoryspeeds.DevicecontrollertransfersblocksofdatafrombufferstoragedirectlytomainmemorywithoutCPUintervention.Onlyoneinterruptisgeneratedperblock,ratherthantheoneinterruptperbyte.Chapter2:Computer-System

StructuresComputerSystemOperationI/OStructureStorageStructure

StorageHierarchyHardwareProtectionGeneralSystemArchitectureStorageStructureMainmemory

–onlylargestoragemediathattheCPUcanaccessdirectly.Secondarystorage

–extensionofmainmemorythatprovideslargenonvolatile

storagecapacity.Magneticdisks

–rigidmetalorglassplatterscoveredwithmagneticrecordingmaterialDisksurfaceislogicallydividedintotracks,whicharesubdividedintosectors.Thediskcontrollerdeterminesthelogicalinteractionbetweenthedeviceandthecomputer.Chapter2:Computer-System

StructuresComputerSystemOperationI/OStructureStorageStructureStorageHierarchy

HardwareProtectionGeneralSystemArchitectureStorageHierarchyStoragesystemsorganizedinhierarchy.Speed

cost

volatility

Caching

–copyinginformationintofasterstoragesystem;mainmemorycanbeviewedasafastcacheforsecondarystorage.Storage-DeviceHierarchy寄存器缓存主存储器电子盘磁盘光盘磁带HardwareProtectionDual-ModeOperationI/OProtectionMemoryProtectionCPUProtectionDual-ModeOperationSharingsystemresourcesrequiresoperatingsystemtoensurethatanincorrectprogramcannotcauseotherprogramstoexecuteincorrectly.Providehardwaresupporttodifferentiatebetweenatleasttwomodesofoperations.

至少在两个运行模式之间提供硬件支持1. Usermode

–executiondoneonbehalfofauser.2. Monitormode(alsosupervisormodeorsystemmode)–executiondoneonbehalfofoperatingsystem.MemoryProtectionMustprovidememoryprotectionatleastfortheinterruptvectorandtheinterruptserviceroutines.Inordertohavememoryprotection,addtworegistersthatdeterminetherangeoflegaladdressesaprogrammayaccess:baseregister

–holdsthesmallestlegalphysicalmemoryaddress.limitregister

–containsthesizeoftherangeMemoryoutsidethedefinedrangeisprotected.ABaseAndAlimitRegisterDefineALogicalAddressSpaceHardwareProtectionWhenexecutinginmonitormode,theoperatingsystemhasunrestrictedaccesstobothmonitoranduser’smemory.Theloadinstructionsforthebaseandlimitregistersareprivilegedinstructions.CPUProtectionTimer

–interruptscomputerafterspecifiedperiodtoensureoperatingsystemmaintainscontrol.Timerisdecrementedeveryclocktick.Whentimerreachesthevalue0,aninterruptoccurs.Timercommonlyusedtoimplementtimesharing.Timeralsousedtocomputethecurrenttime.

Load-timerisaprivilegedinstruction.Chapter2:Computer-System

StructuresComputerSystemOperationI/OStructureStorageStructureStor