文档介绍：’aiTawalbehChapter7:MicroprogrammedControl1ECE271-ircuitsMemorySequenceCounter..ControlsignalsControlsignalsNextAddressGenerator(sequencer)CARControlMemoryCDRDecodingCircuitMemory..CAR:ControlAddressRegisterCDR:ControlDataRegisterInstructioncode2ECE271-anizationMicroprogrammedControlUnitControlsignalsGroupofbitsusedtoselectpathsinmultiplexers,decoders,arithmeticlogicunitsControlvariablesBinaryvariablesspecifymicrooperationsCertainmicrooperationsinitiatedwhileothersidleControlwordStringof1’sand0’srepresentcontrolvariables3ECE271-anizationMicroprogrammedControlUnitControlmemoryMemorycontainscontrolwordsMicroinstructionsControlwordsstoredincontrolmemorySpecifycontrolsignalsforexecutionofmicrooperationsMicroprogramSequenceofmicroinstructions4ECE271-anizationControlMemoryRead-onlymemory(ROM)puterinstructioninitiatesseriesofmicroinstructions(microprogram)incontrolmemoryThesemicroinstructionsgeneratemicrooperationstoFetchinstructionfrommainmemoryEvaluateeffectiveaddressExecuteoperationspecifiedbyinstructionReturncontroltofetchphasefornextinstructionControlmemory(ROM)Controlword(microinstruction)Address5ECE271-anizationControlmemoryContainsmicroprograms(setofmicroinstructions)MicroinstructioncontainsBitsinitiatemicrooperationsBitsdetermineaddressofnextmicroinstructionControladdressregister(CAR)anizationControlwordNextAddressGenerator(sequencer)CARControlMemory(ROM)CDRExternalinput6ECE271-anizationNextaddressgenerator(microprogramsequencer)ransferexternaladdressintoCARLoadinitialaddressintoCARtostartcontroloperations7ECE271-anizationControldataregister(CDR)-orpipelineregisterHoldsmicroinstructionreadfromcontrolmemoryAllowsexecutionofmicrooperationsspecifiedbycontrolwordsimultaneouslywithgenerationofnextmicroinstructionControlunitcanoperatewithoutCDRControlwordNextAddressGenerator(sequencer)CARControlMemory(ROM)Externalinput8ECE271-ogeneratemicrooperationsthatexecutetheinstruction9ECE271-ogenerateeffectiveaddressofoperandformemoryreferenceinstructionSubroutineregister(SB