29-Slave Memories and Dynamic Storage Allocation.pdf29-Slave Memories and Dynamic Storage Allocation.pdf

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IEEETRANSACTIONSONELECTRONICCOMPUTERSTHERANGEOF,ISFROM0TO27RTHEROOTSOFSARECONFINEDBY4R0SQLI4L2THESQSAREUSEDTOCALCULATETHERESIDUESFORTHEFINALSOLUTIONTHEUSEOFTHEDIFFERENCEEQUATIONSAPPROACHREDUCESTHEDIFFICULTPARTOFTHEPROBLEMTOSOLVING28INSTEADOFANINVOLVEDPROCEDUREOFDIAGONALIZINGANMBYMMATRIXTHUSTHECOMPUTERTIMEBECOMESEXTREMELYSHORTANDINEXPENSIVEFORMOFATHOUSANDORGREATER,ANDCALCULATIONRATHERTHENMEASUREMENTBECOMESMUCHMOREPRACTICALSLAVEMEMORIESANDDYNAMICSTORAGEALLOCATIONMVWILKESSUMMARYTHEUSEISDISCUSSEDOFAFASTCOREMEMORYOF,SAY,32000WORDSASASLAVETOASLOWERCOREMEMORYOF,SAY,ONEMILLIONWORDSINSUCHAWAYTHATINPRACTICALCASESTHEEFFECTIVEACCESSTIMEISNEARERTHATOFTHEFASTMEMORYTHANTHATOFTHESLOWMEMORYINTRODUCTIONINTHEHIERARCHICSTORAGESYSTEMSUSEDATPRESENT,COREMEMORIESAREBACKEDUPBYMAGNETICDRUMSORDISKSWHICHARE,INTHEIRTURN,BACKEDUPBYMAGNETICTAPEINTHESESYSTEMSITISNATURALANDEFFICIENTFORINFORMATIONTOBEMOVEDINANDOUTOFTHECOREMEMORYINBLOCKSTHESITUATIONISVERYDIFFERENT,HOWEVER,WHENAFASTCOREMEMORYISBACKEDUPBYALARGESLOWCOREMEMORY,SINCEBOTHMEMORIESARETRULYRANDOMACCESSANDTHEREISNOLATENCYTIMEPROBLEMTHETIMESPENTINTRANSFERRINGTOTHEFASTMEMORYWORDSOFAPROGRAMWHICHARENOTUSEDINASUBSEQUENTRUNNINGISSIMPLYWASTEDIWISHINTHISNOTETODRAWATTENTIONTOTHEUSEOFAFASTMEMORYASASLAVEMEMORYBYASLAVEMEMORYIMEANONEWHICHAUTOMATICALLYACCUMULATESTOITSELFWORDSTHATCOMEFROMASLOWERMAINMEMORY,ANDKEEPSTHEMAVAILABLEFORSUBSEQUENTUSEWITHOUTITBEINGNECESSARYFORTHEPENALTYOFMAINMEMORYACCESSTOBEINCURREDAGAINSINCETHESLAVEMEMORYCANONLYBEAFRACTIONOFTHESIZEOFTHEMAINMEMORY,WORDSCANNOTBEPRESERVEDINITINDEFINITELY,ANDTHEREMUSTBEWIREDINTOTHESYSTEMANALGORITHMBYWHICHTHEYAREPROGRESSIVELYOVERWRITTENINFAVORABLECIRCUMSTANCES,HOWEVER,AGOODPROPORTIONOFTHEWORDSWILLSURVIVELONGENOUGHTOBEUSEDONSUBSEQUENTOCCASIONSANDADISTINCTGAINOFSPEEDRESULTSTHEACTUALGAINDEPENDSONTHESTATISTICSOFTHEPARTICULARSITUATIONSLAVEMEMORIESHAVERECENTLYCOMEINTOPROMINENCEASAWAYOFREDUCINGINSTRUCTIONACCESSTIMEINANOTHERWISECONVENTIONALCOMPUTER2ASMALL,VERYHIGHSPEEDMEMORYOF,SAY,32WORDS,ACCUMULATESINSTRUCTIONSASTHEYARETAKENOUTOFTHEMAINMEMORYSINCEINSTRUCTIONSOFTENOCCURINSMALLLOOPSAQUITEAPPRECIABLESPEEDINGUPCANBEOBTAINEDONEMETHODOFDESIGNINGASLAVEMEMORYFORINSTRUCTIONSISASFOLLOWSSUPPOSETHATTHEMAINMEMORYHAS64KWORDSWHEREK1024AND,THEREFORE,16ADDRESSBITS,ANDTHATTHESLAVEMEMORYHAS32WORDSAND,THEREFORE,5ADDRESSBITSTHESLAVEMEMORYISCONSTRUCTEDWITHAWORDLENGTHEQUALTOTHATOFTHEMAINMEMORYPLUS11EXTRABITS,WHICHWILLBEREFERREDTOASTAGBITSANINSTRUCTIONEXTRACTEDFROMREGISTERROFTHEMAINMEMORYISCOPIEDINTOREGISTERRMOD32OFTHESLAVEMEMORYAND,ATTHESAMETIME,THE11MOSTMANUSCRIPTRECEIVEDNOVEMBER30,1964THEWORKREPORTEDINTHISNOTEWASSUPPORTEDINPARTBYPROJECTMAC,AMASSACHUSETTSINSTITUTEOFTECHNOLOGY,CAMBRIDGE,RESEARCHPROGRAM,SPONSOREDBYTHEADVANCEDRESEARCHPROJECTSAGENCY,DEPTOFDEFENSE,UNDEROFFICEOFNAVALRESEARCHCONTRACTNONONR410201THEAUTHORISWITHTHEUNIVERSITYMATHEMATICALLAB,CAMBRIDGE,ENGLAND1TAKAHASHI,S,HNISHINO,KYOSHIHIRO,ANDKFUCHI,SYSTEMDESIGNOFTHEETLMK6COMPUTERSINFORMATIONPROCESSING1962PROCIFIPCONGRESS62,AMSTERDAM,THENETHERLANDSNORTHHOLLANDPUBLISHINGCO,1963,P6902FERRANTICOMPUTINGSYSTEMS;ATLAS2,LONDONFERRANTILTD,1963SIGNIFICANTBITSOFRARECOPIEDINTOTHE11TAGBITSFOREXAMPLE,SUPPOSER10259,THATIS,3202519THEINSTRUCTIONFROMTHISREGISTERISCOPIEDINTOREGISTER19OFTHESLAVEANDTHENUMBER320ISCOPIEDINTOTHETAGBITSOFTHATREGISTERWHENEVERANINSTRUCTIONISREQUIRED,THESLAVEISFIRSTEXAMINEDTOSEEWHETHERITALREADYCONTAINSTHATINSTRUCTIONTHISISDONEBYACCESSINGTHEREGISTERTHATMIGHTCONTAINTHEINSTRUCTIONNAMELY,REGISTERRMOD32,ANDEXAMININGTHETAGBITSTOSEEWHETHERTHEYAREEQUALTOTHE11MOSTSIGNIFICANTDIGITSOFRIFTHEYARE,THEINSTRUCTIONISTAKENFROMTHESLAVE;OTHERWISE,ITISOBTAINEDFROMTHEMAINMEMORYANDACOPYLEFTINTHESLAVEIFTHESYSTEMISTOPRESERVEFULLFREEDOMFORTHEPROGRAMMERTOMODIFYINSTRUCTIONSINTHEACCUMULATOR,ITISNECESSARYTHATEVERYTIMEAWRITINGOPERATIONISTOTAKEPLACE,THESLAVESHALLBEEXAMINEDTOSEEWHETHERITCONTAINSTHEWORDABOUTTOBEUPDATEDIFITDOES,THENTHEWORDMUSTBEUPDATEDINTHESLAVEASWELLASINTHEMAINMEMORYLARGESLAVEMEMORYSOFARTHESLAVEPRINCIPLEHASBEENAPPLIEDTOVERYSMALLSUPERSPEEDMEMORIESASSOCIATEDWITHTHECONTROLOFACOMPUTERTHEREWOULD,HOWEVER,APPEARTOBEPOSSIBILITIESINTHEUSEOFANORMALSIZEDCOREMEMORYASASLAVETOALARGECOREMEMORY,ANDIWILLNOWDISCUSSVARIOUSWAYSINWHICHTHISMIGHTBEDONEISHALLBECONCERNEDPRIMARILYWITHACOMPUTERSYSTEMDESIGNEDFORONLINETIMESHARINGINWHICHALARGENUMBEROFUSERPROGRAMSAREHELDINAUXILIARYSTORAGEANDACTIVATED,INTURN,ACCORDINGTOASEQUENCEDETERMINEDBYASCHEDTULINGALGORITHMWHENACTIVATED,EACHPROGRAMRUNSUNTILITISEITHERCOMPLETEDORHELDUPBYANINPUT/OUTPUTWAIT,ORUNTILTHEPERIODOFTIMEALLOCATEDTOITBYTHESCHEDULINGALGORITHMISEXHAUSTEDANOTHERPROGRAMISTHENACTIVATEDSEECORBAT63CONSIDERACOMPUTERINWHICHAWORKINGMEMORYOF,SAY,32KAND1,USACCESSTIMEISBACKEDUPBYALARGECOREMEMORYOF,SAY,ONEMILLIONWORDSAND8,USACCESSTIMEINTHESIMPLESTSCHEMETOBEDESCRIBED,PROGRAMSARESPLITINTO32KWORDBLOCKS,EACHUSERMAKINGUSEOFONEORMOREBLOCKSFORHISPROGRAMTHELARGECOREMEMORYISPROVIDEDWITHABASEREGISTER,WHICHCONTAINSTHESTARTINGADDRESSOFTHE32KBLOCKCURRENTLYACTIVEWHATWEWISHTOAVOIDISTRANSFERRINGTHEWHOLEBLOCKTOTHEFASTCOREMEMORYEVE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编号:201401051948156807    类型:共享资源    大小:417.63KB    格式:PDF    上传时间:2014-01-05
  
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