精简指令集计算机

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1、WilliamStallingsComputerOrganizationandArchitecture5thEditionChapter12ReducedInstructionSetComputers精简指令集计算机TopicsMajorAdvancesinComputers计算机的主要改进InstructionExecutionCharacteristics指令执行的特点UseofLargeRegisterFile使用大的寄存器Compiler-BasedRegisterOptimization基于编

2、译器的寄存器优化ReducedInstructionSetArchitecture精简指令集体系结构RISCPipeliningRISC流水线RISCvs.CISCControversyRISC和CISC的比较2MajorAdvancesinComputers(1)Thefamilyconcept系列概念IBMSystem/3601964DECPDP-8Separatesarchitecturefromimplementation将体系结构和它的实现分开Microporgrammedcontroluni

3、t微程序控制器IdeabyWilkes1951ProducedbyIBMS/3601964CachememoryCache存储器IBMS/360model8519693MajorAdvancesinComputers(2)SolidStateRAM固态存储器(Seememorynotes)Microprocessors微处理器Intel40041971Pipelining流水IntroducesparallelismintofetchexecutecycleMultipleprocessors多处理器4

4、TheNextStep-RISCRISC-ReducedInstructionSetComputerRISC精简指令集计算机KeyfeaturesLargenumberofgeneralpurposeregisters,oruseofcompilertechnologytooptimizeregisteruse大量通用寄存器，使用编译技术优化寄存器的使用Limitedandsimpleinstructionset一个有限简单的指令集Emphasisonoptimisingtheinstructionpi

5、peline强调指令流水的优化5Comparisonofprocessors6DrivingforceforCISC（1）CISC-ComplexInstructionSetComputerCISC－复杂指令集计算机WhyCISC?Softwarecostsfarexceedhardwarecosts软件成本高于硬件成本Increasinglycomplexhighlevellanguages越来越复杂的高级语言Semanticgap:Differencebetweenoperationsprovide

6、dinHLLsandthoseprovidedincomputerarchitecture语义间隙问题：HLLs提供的操作和计算机体系结构提供的操作不同7DrivingforceforCISC（2）toclosethegapLeadsto:Largeinstructionsets指令集非常大Moreaddressingmodes更多的寻址方式HardwareimplementationsofHLLstatementse.g.CASE(switch)onVAXHLL描述的硬件的实现8Intentionof

7、CISC复杂指令集体系结构的目的Easecompilerwriting使编译器的编写更容易Improveexecutionefficiency提高执行效率Complexoperationsinmicrocode因为复杂操作能以微代码实现SupportmorecomplexHLLs提供更复杂的HLL支持Atotallydifferentapproach:Simplerarchitecture简化体系结构9ExecutionCharacteristicsDevelopmentsofRISCswerebase

8、donthestudyofinstructionexecutioncharacteristicsRISC的开发是基于指令的执行特性Operationsperformed完成的操作determinefunctionstobeperformedandinteractionwithmemory决定了CPU所要完成的功能及其与存储器的相互作用Operandsused(typesandfrequencies)使用的操作数及其类型和频率determin