(8.4.9)-Ch-09-Instruction Sets Character計算機組成原理

WilliamStallings

ComputerOrganization

andArchitecture

6thEditionChapter10InstructionSets:CharacteristicsandFunctionsWhatisaninstructionset?ThecompletecollectionofinstructionsthatareunderstoodbyaCPUMachineCodeBinaryUsuallyrepresentedbyassemblycodesElementsofanInstructionOperationcode(Opcode)DothisSourceOperandreferenceTothisResultOperandreferencePuttheanswerhereNextInstructionReferenceWhenyouhavedonethat,dothis...WherehavealltheOperandsgone?Longtimepassing….(Ifyoudon’tunderstand,you’retooyoung!)Mainmemory(orvirtualmemoryorcache)CPUregisterI/OdeviceInstructionCycleStateDiagramInstructionRepresentationInmachinecodeeachinstructionhasauniquebitpatternForhumanconsumption(well,programmersanyway)asymbolicrepresentationisusede.g.ADD,SUB,LOADOperandscanalsoberepresentedinthiswayADDA,BSimpleInstructionFormatInstructionTypesDataprocessingDatastorage(mainmemory)Datamovement(I/O)ProgramflowcontrolNumberofAddresses(a)3addressesOperand1,Operand2,Resulta=b+c;Maybeaforth-nextinstruction(usuallyimplicit)NotcommonNeedsverylongwordstoholdeverythingNumberofAddresses(b)2addressesOneaddressdoublesasoperandandresulta=a+bReduceslengthofinstructionRequiressomeextraworkTemporarystoragetoholdsomeresultsNumberofAddresses(c)1addressImplicitsecondaddressUsuallyaregister(accumulator)CommononearlymachinesNumberofAddresses(d)0(zero)addressesAlladdressesimplicitUsesastacke.g.pushapushbaddpopcc=a+bHowManyAddressesMoreaddressesMorecomplex(powerful?)instructionsMoreregistersInter-registeroperationsarequickerFewerinstructionsperprogramFeweraddressesLesscomplex(powerful?)instructionsMoreinstructionsperprogramFasterfetch/executionofinstructionsDesignDecisions(1)OperationrepertoireHowmanyops?Whatcantheydo?Howcomplexarethey?DatatypesInstructionformatsLengthofopcodefieldNumberofaddressesDesignDecisions(2)RegistersNumberofCPUregistersavailableWhichoperationscanbeperformedonwhichregisters?Addressingmodes(later…)RISCvCISCTypesofOperandAddressesNumbersInteger/floatingpointCharactersASCIIetc.LogicalDataBitsorflags(Aside:Isthereanydifferencebetweennumbersandcharacters?AskaCprogrammer!)PentiumDataTypes8bitByte16bitword32bitdoubleword64bitquadwordAddressingisby8bitunitA32bitdoublewordisreadataddressesdivisibleby4SpecificDataTypesGeneral-arbitrarybinarycontentsInteger-singlebinaryvalueOrdinal-unsignedintegerUnpackedBCD-OnedigitperbytePackedBCD-2BCDdigitsperbyteNearPointer-32bitoffsetwithinsegmentBitfieldByteStringFloatingPointPentiumFloatingPointDataTypesPowerPCDataTypes8(byte),16(halfword),32(word)and64(doubleword)lengthdatatypesSomeinstructionsneedoperandalignedon32bitboundaryCanbebig-orlittle-endianFixedpointprocessorrecognises:Unsignedbyte,unsignedhalfword,signedhalfword,unsignedword,signedword,unsigneddoubleword,bytestring(<128bytes)FloatingpointIEEE754SingleordoubleprecisionTypesofOperationDataTransferArithmeticLogicalConversionI/OSystemControlTransferofControlDataTransferSpecifySourceDestinationAmountofdataMaybedifferentinstructionsfordifferentmovementse.g.IBM370Oroneinstructionanddifferentaddressese.g.VAXArithmeticAdd,Subtract,Multiply,DivideSignedIntegerFloatingpoint?MayincludeIncrement(a++)Decrement(a--)Negate(-a)ShiftandRotateOperationsLogicalBitwiseoperationsAND,OR,NOTConversionE.g.BinarytoDecimalInput/OutputMaybespecificinstructionsMaybedoneusingdatamovementinstructions(memorymapped)Maybedonebyaseparatecontroller(DMA)SystemsControlPrivilegedinstructionsCPUneedstobeinspecificstateRing0on80386+KernelmodeForoperatingsystemsuseTransferofControlBranche.g.branchtoxifresultiszeroSkipe.g.incrementandskipifzeroISZRegister1BranchxxxxADDASubroutinecallc.f.interruptcallBranchInstructionNestedProcedureCallsUseofStackExerciseForReaderFindoutaboutinstructionsetforPentiumandPowerPCStartwithStallingsVisitwebsitesByteOrder

(Aportionofchips?)Whatorderdowereadnumbersthatoccupymorethanonebytee.g.(numbersinhextomakeiteasytoread)12345678canbestoredin4x8bitlocationsasfollowsByteOrder(example)AddressValue(1) Value(2)184 12 78185 34 56186 56 34186 78 12i.e.readtopdownorbottomup?ByteOrderNamesTheproblemiscalledEndianThesystemonthelefthastheleastsignificantbyteinthelowestaddressThisiscalledbig-endianThesystemontherighthastheleastsignificantbyteinthehighestaddressThisiscalledlittle-endianExampleofCDataStructureAlternativeViewofMemoryMapStandard…WhatStandard?Pent