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1、Stack堆栈 Specialareainmainmemory存储器中的一个特点区域 Last In First Out 后进先出 StackPointer SP 堆栈指针 betheregisterofCPU Savetheaddressofstack stop始终指向栈顶ProgramSateWord PSW 程序状态字 InthePSWregisterofCPU Savethestateofresultinarithmetic logicaloperationProgramCounter PC 程序计数器 Savetheaddressofnextinstructiontobeexecut
2、ed 补充知识 PC PC SP SP 4 5 8 中断服务例程 General PSW PSW 0 6 7 9 Y 1 2 3 register register General 10 Page211 DesignIssues设计问题 Howdoyouidentifythemoduleissuingtheinterrupt Howdoyoudealwithmultipleinterrupts Page212 IdentifyingInterruptingModule 1 Differentlineforeachmodule多条中断线PCLimitsnumberofdevicesSoftwar
3、epoll软件轮询CPUaskseachmoduleinturnSlow IdentifyingInterruptingModule 2 DaisyChainorHardwarepoll菊花链 硬件轮询 向量 InterruptAcknowledgesentdownachainModuleresponsibleplacesvectoronbusCPUusesvectortoidentifyhandlerroutineBusMaster总线主控 向量 Modulemustclaimthebusbeforeitcanraiseinterrupt MultipleInterrupts Eachint
4、erruptlinehasapriorityHigherprioritylinescaninterruptlowerprioritylines Page213 Example PCBus 80 x86hasoneinterruptline8086basedsystemsuseone8259Ainterruptcontroller8259Ahas8interruptlines Page213 SequenceofEvents 8259Aacceptsinterrupts8259Adeterminespriority8259Asignals8086 raisesINTRline CPUAcknow
5、ledges8259AputscorrectvectorondatabusCPUprocessesinterrupt 7 5DirectMemoryAccess DMA InterruptdrivenandprogrammedI OrequireactiveCPUintervention 干涉 TransferrateislimitedCPUistiedup 占用 DMAistheanswer Page216 直接存储器存取 DMAFunction AdditionalModule hardware onbusDMAcontrollertakesoverfromCPUforI O Page21
6、7 DirectMemoryAccess Page206 DMAModuleDiagram Page218 CPU DMAOperation CPUtellsDMAcontroller Read Write thedirection方向问题 DeviceaddressStartingaddressofmemoryblockfordataAmountofdatatobetransferredCPUcarriesonwithotherworkDMAcontrollerdealswithtransferDMAcontrollersendsinterruptwhenfinished letCPUser
7、vicesforData Page218 DMATransferCycleStealing周期窃用 DMAcontrollertakesoverbusforacycleTransferofonewordofdata 偷用 NotaninterruptCPUdoesnotsaveacontextanddosthelseCPUsuspendedjustbeforeDMAcontrolleraccessesbus 抢用 i e beforeanoperandordatafetchoradatawriteSlowsdownCPUbutnotasmuchasCPUdoingtransfer Page21
8、9 DMAandInterruptBreakpointsduringanInstructionCycle Page219 Busbusyfreebusyfreebusy 偷 DMA断点 中断断点 抢用 偷用 DMAConfigurations 1 SingleBus DetachedDMAcontrollerEachtransferusesbustwiceI OtoDMAthenDMAtomemoryCPUissuspendedtwice效率偏低 Page220 DMAConfigurations 2 SingleBus IntegratedDMAcontrollerControllermay
9、support 1deviceEachtransferusesbusonceDMAtomemoryCPUissuspendedonce Page220 DMAConfigurations 3 SeparateI OBusBussupportsallDMAenableddevicesEachtransferusesbusonceDMAtomemoryCPUissuspendedonce Page220 Interfacing E g FireWire InfiniBand IEEE1394接口无限宽带 Page223 IEEE1394FireWire Highperformanceserialbus高性能的串行总线Fast快Lowcost较低的成本Easytoimplement易实现Alsobeingusedindigitalcameras VCRsandTV 数码照相机 录像机 电视 Page224 InfiniBand无限宽带 I Ospecificationaimedathighendservers服务器IntendedtoreplacePCIinserversIncreasedcapacity expandability flexibility Page229
