///CommonMBusSpecs.tiogaWrittenby:Sindhu,September1,19841:51:14pmPDTLastEditedby:Sindhu,March22,19859:17:20pmPSTLastEditedby:Barth,December13,19842:08:47pmPSTLastEditedby:McCreight,March22,19855:13:37pmPSTCOMMONMBUSSPECIFICATIONSTheCommonMBusDescriptionandSpecificationsDRAFTofMarch22,1985..nearlydone..Releaseas[Indigo]Documentation>CommonMBus>CommonMBusSpecs.tioga,.presscCopyright1985XeroxCorporation.Allrightsreserved.Abstract:ThismemoproposesacommonMbusforDragonandCworkstation.ItisintendedtobeusedbothasaconvenientsourceforinformationabouttheMbusandasareferencemanualforbusspecifications.ThememobeginswithabriefoverviewoftheMbus.Itthenlistsallthebussignalsanddefinesthemeaningofeachsignalgroup.Next,itusesthesesignalstodescribeindetailhowthebusoperatesatboththecycleandtransactionlevels,andhowcertaintransactionsareusedtomaintaincacheconsistency.Finally,itgivesthedetailedtimingofthebustransactionscurrentlydefined.XEROXXeroxCorporationPaloAltoResearchCenter3333CoyoteHillRoadPaloAlto,California94304ForInternalXeroxUseOnlypО_,НБО]┘НБНХН<Н@Н!щН#jН&╟Н+≤Н-ЦО[щНБНЧНEН≤Н°Н"Н$?Н'┘Н,nН.╦ОZ6НБНЧНEН≤НиН#Н%TН( Н-┐Н/нОX▐НБНЧНEН≤ НаН$&Н&cН)╘Н.▓Н0щqОVНБrНЮОVОVН╪qНОVОVНХrНоОVОVН╣qН(ОVrОVНОsОMоНБН Н оН#ШtОHыНБ НDНІ ОCЦНБН⌠НHН PН$WО@шНSНЎuО;ЕНБНeО;ЕН╒vНО;ЕО;ЕНgП=О:>НБwО5HНБuО5HНяН9НН├Н#кН%└Н(сxО1ЫНБvО1ЫНєНRН 5Н'Н(шН/aН1┌Н4мН7┬Н=<Н@°О0RНБНfННЫН"nН$┼Н&ЧН*ТН.ЁН1Н2╘ Н:∙Н?жО.╙НБ Н·Н╩Н6НтН!°Н$zН&eН'═Н.<Н3cН5⌡Н8cО)ЄНБНъНRННFН■Н"ЪН)+Н*СН-─Н/2Н2ЫН4SН7╡Н:╧Н<╦Н?FО( НБН ННqН#Н%RН'=Н+Н/└Н5 Н9Н:xН>О&fНБН(Н3Н│НwН"ЎН&6Н)Н,&Н2┼Н4┼Н88Н; Н?0О$ЎНБ Н╣НWНcН!╠Н&бН/EН1ВН5ЁН7∙Н=╞О#НБНёННґН#чН&цН,ЇН1│Н3═Н6├Н9╧О!pНБНyОэНБvОэН.╪Н2Ъ О5Н.╪Н2Н5&Н;гО█Н.╪Н2YН7cН9МОФН.╪Н2Н5┼ Н<6tО IНБНЫН▒Н"=Н&о TVm$ИCOMMONMBUSSPECIFICATIONS2Contents1.Introduction2.BusSignals3.BusOperation4.BusTimingFORINTERNALXEROXUSEONLYqОgНЮrН чОgОgН!╨qН&ОgОgН'ФrН(нОgОgН)ЁqН+&ОgrОgН+МvОgНEиzО^УНБ{О[їНєН0ОXXНєН0НРОU НєН0НРОQ╩НєН0НРrОН ыН#ґН*$Н.÷Н1GkTVm$_COMMONMBUSSPECIFICATIONS31.IntroductionTheMbusisahighbandwidthsynchronousbusthatinterconnectsamultiprocessorsystem.FivekindsofdevicesconnecttoanMbus:caches,thatintermediatebetweenprocessorsandthebus,memories,someofwhichmaybemultiported,I/Odevicecontrollers,amap,responsibleforinformingthecachesaboutthecurrentvirtual-to-physicalmemoryaddressmapping,anarbiter,thatassignsmastershiptoatmostonerequestingdevice.ThisdocumentisthespecificationfortheMbusinterfaceofcaches.ItimpliesrestrictionsonotherdevicesthatconnecttotheMbusaswell,butitisnotintendedtospecifythosedeviceswithanycompleteness.MbuseshaveabriefbutinterestinghistorywithinXerox.Thecacheconsistencyprotocol,whichmanyconsidertobethekeyideathattheMbusimplements,firstoccurredtoDashiellofXeroxEDandThackerofXeroxPARCabout1980.TheoriginalintentionwasthatEDandPARCdevelopacompatibleMbusthatcouldbeusedbyPARC'sworkstationprojectsandED'sprinterprojects.Notenoughenergywasdevotedtoovercomingtheincreaseofentropy,andbysummerof1984EDnearlyhadaworkingMbusandPARChadapaperdesignofaratherdifferentMbus.SincethenithasbecomeclearthattheEDMbusasitexiststoday(weshallcallthattheESSMbus)willnotsatisfyallofED'srequirementsforitsplannedCworkstationline,andsoconsiderableeffortisbeingdevotedatEDandPARCtosettlingonacommondesignforthesecond-generationMbus.ThisdocumentisthefirstdetailedproposalfromPARCinthatdirection.ManyoftheapparentlyarbitrarychoicesinthefollowingsectionsaredictatedbyastrongdesirethatexistingESScachesfunctionaswellaspossibleonthenewcommonMbus.Theremainderofthedocumentgoesintogreaterdetailaboutthestructure,operation,andtimingoftheMbus.Thenextsectionliststhebussignalsindetailandgivesthemeaningofeachsignal.Section3nextusesthesesignaldefinitionstoexplainhowthebusoperates:itdiscussesarbitration,liststhesetofbuscommandscurrentlydefined,showshowthesecommandsareusedineachofthepossibletransactions,showshowtransactionsareusedtomaintaincacheconsistency,andintroduceshousekeepingoperationstodealwithaddressspaceswitchesandmultiportmemories.Finally,Section4discussesthetimingofarbitrationandofeachtransactionindetail.2.BusSignalsAnMbusconsistsofthreeindependentgroupsoflines.Thefirstistheclockinggroup.Thesecond,calledthearbitrationgroup,assignsbusmastership.Thethird,calledthetransfergroup,transportsdataoncemastershiphasbeenestablished.Thefollowingdescriptionusesthesenamingconventions:S[a..b)denotesagroupof(b-a)linesthatencodethebitsrepresentingthesignalS;mostsignificantbitsofthesignalarewrittenleftmost,andhavethesmallestnumericindex.Asignalrepresentedbyasinglewireiswrittenunencumberedwiththe[)notation.Allsignalsareassumedtofollowpositivelogicunlesstheyhavean"n"asthesecondFORINTERNALXEROXUSEONLYqОgНЮrН чОgОgН!╨qН&ОgОgН'ФrН(нОgОgН)ЁqН+&ОgrОgН+МvОgНEиzО^УНБНЎqО[іНєННbН~НoНН!кН), Н1═Н4ҐН8Н@ТОYЪНБ ННrН ≈Н$KН&Н*мН/ДН1▓Н3┐Н5]ОXННґН{Н"uН'Ц Н.{Н12Н3▓ОV#ННіН9НРН#Н&Н'УОT5ННяНОRGНН+Н⌡ Н!кН%Н,nН/кН5Н9ВН=TОP═Н'Н"gН'тН,ЎОN╡ННУНЎН▄Н! Н(Н)╠Н+IН.іН1Q Н8ОL6НєНЁННwНлН&╔Н(ьН+-Н,ЭН/┬Н5#Н6рН;ИН=VОJ▐НБНнНеНTН Н"лН'сН)rН+бН-▄Н0Н1╡Н4ХН7YН8═Н9ЭНRО?оНБНШН_Н┌НК Н#|Н(фН+╔Н/4Н3НН:;Н=4О>(НБН\НН=НК Н$^Н&╪Н+ЩН-╣Н3#Н5ыН7тН= Н>ьО<─НБН^Н}Н&НBН┼Н UН"щН%├Н)эН,┘Н-═Н1sН5ЄН7^Н8yНSО+#НБН╛Н1НёНPНН"_Н'LН,?Н-├Н0╗Н3╣Н7QН;O О)|НБНoН!ННBНЇН"}Н#╡Н)WН0RН2СН51Н7,Н8цН;9О'уНБНЗН▄НтН"Н%жН,ЖН/└Н2ЗН4ЦН8OН:BН<эО&-НБНХН#НUН&Н(┘Н+НН-кН3ЄН7ўН?gО$├НБ НnНЙ Н$uН&Н(вН+оН0√Н4)Н9jН;ЧО"ъНБНаН(Н!dН"УН)Н+уН0▄Н2╒ Н9цН<вН>МО!7НБ НчН▄zО НБНЎН qОKНєНзН≈ННСН▐Н!Ш Н)нН.7Н/сН3╟Н6kН9&Н:upН<ЇОKОKН=RqОёНБН╣Н┤НkН]pН!ЇОёОёН"g qОёН(dН,╧Н1DН3у Н;▀Н>]ОЭНБНыpН9ОЭОЭН╘qОЭН3Н█ Н$НН'СН+: Н2 Н4∙Н7ЯО│НєНўНТ Н"8Н%dН) Н.GН7@О│Н;ІН@ТОыНБНОНЁНН`Н9Н"ЖН%`Н( Н/ОН2YН6OН8Н;├ О2НБНtННnНIН█pН 1О2О2Н ■qН$иО2О2Н%√Н(>Н+upН-еО2О2Н.IqО2Н2зН8.Н<╣Н>3О▀НБ Н┌НЁНН2Н!vН#Н(Н1⌡Н4ЛН7─Н9Н?кО ЦНБНbНфНfН%Н!nН&■Н)ЖН.)Н1IН4═Н6║Н9^Н;Н=▄rОН ыН#ґН*$Н.÷Н1GЪ bTVm$бCOMMONMBUSSPECIFICATIONS4characterofthesignalname.Someoftheselineshavepullupresistorstoensurethattheyremainunassertedduringcycleswhentheyarenotdriven.Theseresistorsdonotsupplyenoughcurrenttode-assertalineinonecycle;howevertheymustde-assertthelineinaminimumresetperiod.2.1ClockingGroupTheMbusistimedincyclesofatwo-phaseclock.ThephasesarenamedAandB,andaclockcyclebeginsattheleadingedgeofAandendsatthetrailingedgeofthefollowingB.AsignalthatconformstostandardMbustimingisdrivenontotheMbusassoonaspossibleafterthestartofphaseA,andissensedfromtheMbusbylatchesthatareopen(enabled)duringphaseB.ThismeansthatthelargestportionofaclockcycleisavailablefordatatopropagateandstabilizeontheMbus.AllofthefollowingsignalsexceptMPhAandMPhBconformtostandardMbustiming.MPhAThisisassertedduringthe"first"phaseofatwo-phaseclockcycle.MPhBThisisassertedduringthe"second"phaseofatwo-phaseclockcycle.MHoldThestateofthislineassampledattheendofcycleidetermineswhetherthestateoftheMbussystemattheendofcyclei+2istobeidenticaltoitsstateattheendofcyclei+1.MnResetThislineisheldassertedduringpower-up,andisassertedforatleast128consecutivecycleswheneveritisasserted.ThecyclefollowingthecycleinwhichMnResetisde-assertedisavalidMbuscycle.2.2ArbitrationGroupThearbitrationgroupconsistsofapairofrequest/grantlinesforeachbusrequestor,andoneothersharedlinecalledMnNewRQ.Asingle,centralarbitertime-multiplexesthetransfergroupamongseveralcontendingdevices.Eachofthesedevicesmakesrequeststothearbiterusingitsdedicatedrequestline,andthearbitergrantsmastershipofthebususingthededicatedgrantlines.Adevicethathasbeengrantedthebusiscalledbusmaster.Thesequenceofcyclesinitiatedbyamasterwilltypicallyinvolveatleastoneotherdeviceonthebus;suchadeviceiscalledaslave.MnRq[0..16)FORINTERNALXEROXUSEONLYqОgНЮrН чОgОgН!╨qН&ОgОgН'ФrН(нОgОgН)ЁqН+&ОgrОgН+МvОgНEиqО_/НБНкН└НЦНнО\ЁНєНuН*Н╟НГН!)Н%▄Н*тН,~Н0ЮН3╙Н6ІН;Y О[НБН█Н©НўНЬН!├Н$5Н)уН.Н3≤Н5ыН8┬Н=4ОYeНБНбН┤НNН▐Н\Н! Н#ЦН'ФН-─Н0іН4%Н9ЛНЇОJ│НБНBНН╣Н╡Н:Н Н!^Н$яН*РН/cН3FН5▐Н8╙Н<ОН?ЎОHыНБН/НН╛НхНNН!ЄН#Н(юН*ПН-ГН/┬Н5эН8├Н=фН?ЎОG2НБНбНAН НZНюН ьН%NН)╔Н.&Н0ЦН5DН:нН<┐ОE▀НБН╪НSpОB;НБqО>ЛНєНЎН)НaНяН"1Н&jН*KН,Н-.Н3╟Н7DpО;°НБqО8LНєНЎН)НaНяН"1Н(#Н,Н-ЎН.ХН5jН8ЧpО4ЩНБqО1ґНєН┴НхН▐Н>НН ЎН&:Н'ЮН*MН-Н.ыН2ZН3O Н:cН?ЎО0НБН$ННН_НJНРН~Н!(Н#≤Н&aН(+Н+╞Н.╧Н06Н1УН3ВН9≤Н;XН=CН@┘О._НБНAНЫН╡Н%pО+НБqО'©НєНЫНКН▓НХН"ZН'Н-оН0бН2iН7шН:TН<(Н?┬О&НБ НJНTН °Н"Н#┘Н)ЎН,╙Н00Н6VН8хНО$qНБНйН5 НRНЎНХН#OН%)Н'ю{О╔НБН Н/qОVНєНЇ НІНСН%.Н'"Н(┤Н+ pН-▌ОVОVН.qН1╙ОVpОVН2ZqОVН6-Н9ёН<Н?┤О╞НБ НpНIННвН#^Н&6Н*OН2ЯН4═Н9Н=ґОНБН5НyН iН$PН(╨Н-/ Н41Н9÷Н<ВН>∙О`НБН═pНнО`О`НRqО`НГН┼Н ъН%EН(ДН*ЁН0ъН5╗Н8╛Н;YН=ґpО╧НБqО╧НП НхНsНеН NН#ИН&;Н,cН/ИН3ДН5cН9 НаОНБНМНXНЗНqНspН!ООН"+qОН&fН)IН/<Н1Н5Н:rН∙ОPJНБНbНєНўН╔НBН ЖН&kН( Н*├Н0Н4*Н7 Н<┴Н?йОNёНБНїН÷НШН>Н!NН"ЬН&ЖН)hН-rН3┌Н4ЙН:цН=VpОKSНБqОHНєН╠НZН╧НН&Н(zН*ЬН/hН1╨Н7Н8ҐН:┼Н=ОF\НБННаН8Н НtН#DН(*Н,Н-хН1╩Н3УН7ХН:pН;ЦН@oОD╣НБ НGН▀НзНQН▓Н! Н'░Н)Н+іН/┐Н2▀Н5/Н7▓Н8╙Н<Ч{ОAeНБНН─qО>НєН|Н┤Н┴Н"┴Н$BН-CН/(pО:еНБqО7uНєН╪НqНшНН ╞Н%Н)Н,гН-ОН1TН7ЁН9Н<ГО5нНБНвНYНbННЗН зН&Н)шН+фН.Н2sН4Н6jН;" О4&НБНіН╒ННhН∙Н░Н!ПН$хН(;Н)ТН,SН1pО0жНБqО-├НєН~ Н(Н■Н юН#тН%[Н)ГН-HН1O Н94О+ъНБН≥НдНzН!Н$WН&iН(Н+╙Н.п Н4╒Н8█Н<Н?йО*8НБН═Н▒Н$Н)qН,bН.)Н2OН5 Н='Н>╚О(░НБННoНhН4НЦН!ЯН#═ Н*Н+╨Н/°О%AНБ Н≈Н|О"еНєН Н┘Н=Н╒Н!UН#Н+Н,фН3pН53Н:ІН=bН?┤О!НБНЇНАНvН!РН&&Н*ЁН-.Н2Н4фН8ґН;─Н>═ОvНБН▓НиНГН ьН"─Н%gН(.Н0Н4√Н8Н9▄Н:ЯН@"ОоНБН;Н╠НОНЇНН"╨ Н+JН.Н4ЗН:яН?йО'НБНЛНН©Н·ОвНБНsНXП"О[НєНсНН3НbН чН"TН*+Н+╛Н1ИН3З Н<╞ОЄНБНХН НН┐Н╛Н!√Н%╒Н(╪Н+ЛН1ҐН6Н8ОdНБН2НОХНєНЇНАНFНZН╨Н!Н(пН*5Н2!Н4 Н<╞О AНБНХНwН╔Н^Н"Н%Н(MН.Н2wrОН ыН#ґН*$Н.÷Н1GЪхTVm$mCOMMONMBUSSPECIFICATIONS6MParityThislinecarriestheparityofMTransport.TheparityisoddanddrivenonecyclelaterbythedevicethatdroveMTransport.MnSharedThislineindicatesthatacopyoftheaddressedmemorywordispresentinaslavecache.Thislinehasapullupresistor.MnAbortThislinepreventsmemoryfromrespondingtoaReadQuadandallowsacachetorespondinstead.Thiswireisnotlogicallynecessarytothecacheconsistencyprotocol,butitallowsaperformanceoptimization.Thislinehasapullupresistor.MnHousekeepingInProgressFollowinganycycleinwhichthislineisnotasserted,everycachethatisdoinghousekeepingassertsit.Followinganycycleinwhichitisasserted,everycacheactivelyde-assertsit.Twounassertedcyclesinsuccessionmeanthatnohousekeepingisinprogress.Thislinehasapullupresistor.MnErrorThislineisusedtosignalabuserror.Theonlybuserrorcurrentlydefinedisbusparityerror.Thislinehasapullupresistor.3.BusOperationMbusoperationisspecifiedattwolevels:cyclesandtransactions.Asexplainedearlier,acycleisonecompleteperiodofthesystem-widetwo-phaseclock.Atransactionisasequenceofcontiguouscyclesinitiatedbysomebusmaster.Duringthefirstcycleofeverytransaction,MnAdCycleisasserted,MCmdspecifiesthetransactiontype,andMAddrspecifiesanaddress,whoseinterpretationvarieswithtransactiontype.Subsequentcyclestransferdata,performothermanipulations,orsignaltheendofthetransaction.Recallthatthedevicethatinitiatesatransactioniscalledthebusmaster,andotherdeviceswithwhichitinteractsarecalledslaves.Busmastershipisgrantedbythearbiter.Thusoverallbusoperationisasimplepipelinedcyclicprocessofarbitrationfollowedbytransactionexecution.Thedescriptionbelowfirsttakesuparbitration.ItthendescribesthevariousMbuscommandsaswellasthesetoftransactionsthatusethesecommands.Forcompleteness,italsodiscusseshowcachesmaintainconsistencyofmultiplecopiesofshareddata.Finallyitdiscussesasetofhousekeepingoperationsthatdealwiththemappingproblemsintroducedbymovingaprocessorfromoneaddressspacetoanother,andwiththeconsistencyproblemsintroducedbymultiportmemories.ThedetailedtimingofarbitrationandofeachofthetransactionsisnottakenupherebutislefttoSection4.3.1ArbitrationFORINTERNALXEROXUSEONLYqОgНЮrН чОgОgН!╨qН&ОgОgН'ФrН(нОgОgН)ЁqН+&ОgrОgН+МvОgНEиpО_:НБqО[КНєНпН≤ННvН"─Н$K Н,ЖН/АН3ЙН5hН8GН;Н?rОZDНБНUНzНvНжНН ХН$и pОVУНБqОSіНєНтН═НgН KН!▀Н$РН&аН)7Н/ёН5&Н8еН:FН?0Н@ТОQЪНБНIНЯННаН6Н `Н$гpОN╟НБqОKbНєН╣НdНЮН"EН%ё Н,ЇН.]Н/Н6]Н9Н=1Н>RОI╨НБН╩Н'Н НOН"┬Н$Н&ҐН,UН2▓Н4kН6УН:К ОHНБН╗Н)Н─НґНв Н%шН.╞Н1йН4─Н6УН8Н<┘pОDдНБqОAvНєН НҐН,НуН#ъН&}Н)/Н*≈Н-Н2⌠Н6CН:Н<уН>=О?нНБН╛Н&НўН%ZН(%Н+цН-²Н1жН3WН4НpН:╗О?нО?нН;CqО?нН>RО>'НБНа НжНгНк Н%pН)GН*т Н1LН4ЛН7≥Н9О<─НБНNНЭНEН_НН ▀Н!╣Н&pО91НБqО5БНєН©НwНДН"НяН!ЎН"ИН%│Н)рН,╚Н/гН2_Н5рН;╟Н@╡О4;НБНyНpНЎНьН▌Н"Н#-Н'⌠zО-·НБНЎН qО*OНєНgНФНЫНNН"РН$tН' Н+6Н/Н1ІН9ДН;чО(їНБН©Н*НчН▀НxН#╒Н(=Н*8Н,ь Н4шН;÷Н@▒pО'НБ qО'НрН4НUН4НЦ Н&кН*╦Н0Н2Н5▐Н8Н=UО%YНБНzН▀Н7Н)НН%ёН-·Н/BН5Н:Н?ЎО#╠НБ НОНhН1Н!7Н&аН(цН.Н2V Н;Н?О" НБ НЛНС Н!mН%rН*┼Н-УН3[Н7 Н@ZО cНБНвН@ННдН.Н$Н(\Н+4Н-²Н1ЛН4дН9НН;" О╩НБНVНVНҐН\Н-Н МН$■Н)eН,┴Н0÷Н1ЩН7─Н9шН=шОНБН╨ НаНMНnН!▀Н$Н) Н-9Н1ъН4≈Н:АНН7АН<цН@oОґНБН7НЮНЛН= Н#bН)\ Н0?Н2,Н8=Н?FОНБН/Н·Нl Н!EН$Н%ъН)%Н*СН-hН4ЩН6}Н9Н<эН?О ^НБНcНоНDНРНр{О НБН rОН ыН#ґН*$Н.÷Н1G*TVm$▓COMMONMBUSSPECIFICATIONS7ThesignalsinvolvedinarbitrationaretheMnRq-MnGntpairsrunningtoandfromeachpotentialmasterandthearbiter,andasinglelineMnNewRqusedtoincreasethefairnessofarbitration.Adevicerequeststhebusbyassertingitsrequestline.IfoneormoreMnRqlinesareasserted,andthereisnomaster(grantee)atthemoment,thearbiterperformsagrantcycleinwhichitissuesthebusbyassertingMnGntforadevicethathasMnRqasserted.ThebusmasterkeepsMnRqassertedwhileitstillwantsthebus,andthearbiterinturnkeepsthatmaster'sMnGntasserted.Ifthemasterisexecutingalongsequenceofcyclesthatisnotrequiredtobeatomicwithrespecttootherdevices,itmayassertMnNewRqtoindicateitswillingnesstogiveupthebusifthereareotherrequestspending(forcorrectoperation,MnNewRqmustbeassertedonlybythecurrentmaster).MnNewRqcausesthearbitertodoagrantcycleeventhoughthecurrentmasterstillhasMnRqasserted.Thisstrategypreventsamasterfromhoggingthebus(unless,foratomicity,itneedsto).Atthesametime,itavoidswastingcyclesinthecasethatnodevicesarewaitingtogetthebus.Asolutioninwhichthemasterreleasesandreacquiresthebus,forexample,doeswastecyclesinthiscase.3.2MBusTransactionsTherearecurrentlyninemastertransactions:ReadQuad,WriteQuad,WriteSingle,MapRef,MapRefDirty,IORead,IOWrite,IOReadFlow,andIOWriteFlow.Thebusmasterinitiatesamastertransactionbyassertingtheappropriatecommandwithanaddressofsomekind.ThiscommandandaddressisinterpretedbyeverydeviceattachedtotheMbus,andoneormoredevicesdecidetoactasslavesduringtheremainderofthetransaction.Somemastertransactionsconsistofafixedsequenceofcycles:WriteSingle,IORead,andIOWrite.Othersareflow-controlledbytheMnDVline:ReadQuadandWriteQuad.Theremainderareflow-controlledbytheslavetransactionDone.Flow-controlledmastertransactionsbeginwithafixedsequenceofcycles,dependingonthetransaction,waitfortheirflow-controllingevent,andthenterminateinafixedsequenceofcycles,againdependingonthetransaction.Flow-controlledtransactionsmustselectexactlyoneslave.TheMbusspecificationincludesmeansfordetectingwhenthisisnotso.(Ohyeah?Howdowedothis?WhateveriseasiestforEDshouldprobablyprevail.)Transactionsthatareflow-controlledbyDonemaycontainsubtransactionsthatarenotflow-controlledbyDone.Duringthosesubtransactions,theslaveofthemaintransactionactsasmasterofthesubtransaction.IOdevicesmayrespondtoanyorallofthefourIOtransactions.MbuscommandsarecarriedintheMCmdfieldandarevalidwhenMnAdCycleisasserted.Twelveofthesearecurrentlydefined,andtheotherfourarereservedforfutureuse.Inthedescriptionbelow,thedecimalnumberincurlybracketsafterthecommandnameindicatestheencodingofthecommand.(Onpage8ofthe21Jan84ESScachespecification,thereare(optional?)waitcyclesappearingbeforeseveraltransactions.Whatdoesthismean?)ReadQuad{0or2(sigh!)}ThiscommandisissuedbythemasterduringthefirstcycleofaReadQuadtransaction,whichreadsaquadintothemasterfrommemoryorfromanothercache.FORINTERNALXEROXUSEONLYqОgНЮrН чОgОgН!╨qН&ОgОgН'ФrН(нОgОgН)ЁqН+&ОgrОgН+МvОgНEиqО_/НєН~НОН▀Н ; Н'Н)VН+╦ Н5Н8}Н=ІН?gО]┬НБНoНгН╘Н @Н#Н%єН*⌠Н-qН.аН2сН5╟Н= Н@oО[ЮНБННXНBНЕН$[Н%рН*Н/DН1▌Н4Н5УН;└Н=IОZ9НБН√Н(НДН╧Н]Н чН$)Н&█Н,.Н.УН2▐Н4Н6"Н:ёН@┘ОX▓НБН+НшН$Н~Н#DН$WН'уН+1Н,иН0юН2Н5йН8Н:■НОMрНБН^НзНЄН!i Н(Н/hН2ТН5Н:bН=÷Н?ЎОL*НБН╞Н{Н ЄН$ЯН'TН+хН-zН/└Н0╠Н4HН7ЎН;Н?ЎОJ┐НБН█НъНaНЇН! Н&ъН)зН.яН47Н5BН9■Н<эОHэНБН,НґН▄НЄ Н ТН"5Н&Н(ыН*©Н- Н0pН3ьН5Н9GН>'ОG4НБН╨НCН\НTН└Н wН"ТН'РН)йН,=Н.фН2▄Н4CН9╞Н;┤Н?ЎОE█НБНRН\Н Н!║Н$Н&ОН)-pН.ЧОE█ОE█Н/ўqОE█Н2Н5бН9╧Н;gН> {ОB>НБНННфqО>ОНєН┌Н╠Н kН$aН)ўН2└Н:· О=HНБНыНhН)Н/sН6 Н?gО;║НБНН?Н9Н$Н)⌠Н+!Н/У Н7UН9╣Н?ЎО9ЫНБ Н:Н∙Н╗Н!▓Н&uН('Н+ЁН/╠Н2еН9Н;оН@╡О8RНБ НУНЯН╔НЙН%fН'Н)tН+OН.>Н0ЖН3╒Н5fН8ЫН=цО6╚НБН░НдНrН]НнН-Н%еН'~Н)щО4/НєН╙НJН!ШН&їН(░Н)ЙН-≤Н3╠Н5 Н:;О2┬НБН┼НZНАН"uН$АН.▀Н0═Н3Н7ОН;8О0АНБН═ Н╡Н▒Н#/Н%┼Н/"Н1$Н3▀Н6Ы Н=ШО/9НБНхН Н$┬Н(:Н+<Н,MН/╡Н5┌Н7"Н;YО-▓НБНН║Н"НHН ╡Н$&Н.RН2▀Н5pН8бН?Н@ТО+КНБН`НHННPН!ЗН(©Н*еН-$О)pНєН"Н$#Н( Н,KН1gН4⌠Н9уН=-Н?┤О'хНБНйН3Н {Н"ҐН(╙Н,dН/ Н0{Н2ТrН6&О'хО'хН6┤Н8pН;СН>╗Н@JО&!НБНЬНщНSНМНвН"Н$≤Н(╔Н-дqО&!Н3зНБО>НБНAН╒НbН!Н#sН)ZН+Н-srОцНєНЪН╡НЎН4Н/НхНФН Н"УН& Н,©Н/╗Н1≥ Н72Н9╗Н<ИОНБНUНЭН╚Н╛Н"9Н$TpОмНБН▒НvН/НcqО~НєНЮНdНРН!8Н#VН%ьН*kН.ЧН1─Н4{Н8Н9ЛН;8О вНБННН≤Н╘Н"Н$нН'Н+lН.╨Н4Н5╨Н9Н=ЗrОН ыН#ґН*$Н.÷Н1GTVm$зCOMMONMBUSSPECIFICATIONS8Aquadisfourcontiguous32-bitwordsalignedinphysicaladdressspacesuchthattheaddressofthefirstwordis0MOD4.DuringthisfirstcycleMAddristhephysicaladdressofoneofthewordsinthequad.ThetransactionthenconsistsofzeroormorewaitcyclesuntiltheMnDVlinesignalsthatthememorysystemisresponding.TheaddressedwordwillbeassertedonMDatabytheslaveduringthatcycle.TheremainingwordsofthequadwillbeassertedonMDatabytheslaveinsubsequentcyclesinanorderdeterminedbytheiraddressMOD4:AddrTransportorder0=>{0,1,2,3}1=>{1,0,3,2}2=>{2,3,0,1}3=>{3,2,1,0}Cachesbuilttothisspecificationwillunderstandboth0and2asencodesforReadQuad,butwillissueonly0.WriteQuad{1or3((sigh!)}ThiscommandisissuedbythemasterduringthefirstcycleofaWriteQuadtransaction,whichwritesaquadfromthemastertomemoryandtoothercaches.InthefirstcycleMAddrcarriestheaddressofthequadwhich,unliketheaddressforaReadQuadtransaction,mustbe0MOD4.InsubsequentcyclesthemasterassertsthedataofthequadonMData,inorderofincreasingaddress.ThemasterreleasesMnRqforthistransactioninthecycleafterMnDVisassertedbytheslave.Cachesbuilttothisspecificationwillunderstandboth1and3asencodesforWriteQuad,butwillissueonly1.WriteSingle{7}ThiscommandisusedbythemasterduringthefirstcycleofaWriteSingletransaction,whichwritesasinglewordintothephysicaladdressspace.WriteSingleneverwritesthewordtomemory,butonlytocachesthatalreadyholdacopyofthequadcontainingthewordbeingwritten.MAddrcarriesthephysicaladdressofthewordinthefirstcycleofthetransaction.Thedataisassertedbythemasterinthenextcycleofthetransaction.MapRef{12}Thiscommandisusedbythemasterduringthefirstcycleofavirtual-to-physicalpagetranslationtransaction.Useofthistransactionindicatesthatthemasterintendstoreaddatainthereferencedpageofitsvirtualaddressspace(eachmastermaybeoperatinginadifferentvirtualaddressspace).InthatfirstcycleMAddr[7..32)containsavirtual512-byte-pagenumber.Thefinalcycleofthetransactionisthecycleinwhichtheslave(map)assertsaDonecommandthatcontainstheresultsofthetranslationinMAddr.(DoestheESScachereallyrequirethreedeadcyclesaftertheDone?Isthatbecauseitsmatcheristiedup?)FORINTERNALXEROXUSEONLYqОgНЮrН чОgОgН!╨qН&ОgОgН'ФrН(нОgОgН)ЁqН+&ОgrОgН+МvОgНEиqО_/НБpНyО_/О_/Н*qО_/НжНLН[ НWН#YН'pН,NН.Н3_Н8TН<Н?PО]┬НБНnН┘НkНЬНЩН!╡Н#KrН$╛О]┬О]┬Н%ЎqО]┬Н(1Н*⌡Н/▒Н2_Н5dН9Н>&Н?ЎО[ЮНБН/ННрН~Н7Н!≈Н%ёН'QН)╠ОYeНєН┐ Н┤НЄН#╪Н%|Н(┤Н*SН-МН0НН4МН8;Н:╒Н?gОWҐНБНMННrНшН"RН#╨ Н+╘Н.}Н4оН8SН:ЗН<ГОVНБНБН▌Н└НщН=Н!╗Н$oН(╠Н+┐Н1ЧН6Н7ЇН:Н=┬Н@-ОToНБННЖН■Н{НеН"Н#╠ Н*еН.їН0AН2Н5╪ Н<ПН>вОRгНБrНлОRгОRгНщqОRгН$ОPLНєНSН╘ОMпНєНьНnН╚Н8НеОKTНєНьНnН╚Н8НеОHьНєНьНnН╚Н8НеОF]НєНьНnН╚Н8НеОCАНєНjНдН├Н:Н&1Н(П Н0+Н3{Н4цН7█Н8уН:√Н?АОB:НБН Н║НMН╘Н!цpО>ЙНБНКНпН┴НҐqО; НєНшНZНЦН!$Н#=Н%╨Н*GН.жН1RН4HН7ыН9╞Н:ЖО9СНБНNНsН▄НмН#cН&БН)YН-АН/іН5+Н7ЗН9юН=vО8LНБНҐН)Н Н▄Н█Н"СН%_Н*UН,Н.├Н2Н6┐Н:хН=4О6єНБНBН▌Н≈Н!Н$≥Н&╛rН(О6єО6єН)qО6єН+~Н-тН/ф Н7Н;+Н=ўО4ЩНБН5Н≥Н╒Н_НцН FН"PН'`Н)Н,кН.┬ Н5Н:яН=ўО3VНБНФНQН┴Н% Н$Н%цН(Н+┼Н.юН3xН4чН:Н<Н>_О/3НєНjНдН├Н:Н&1Н(П Н0+Н3{Н4цН7█Н8уН:√Н?АО-▀НБ НbНЦН▌НКН"pО*<НБ НfqО&ЛНєНЕНnНН eН"┬Н%Н)їН.@Н0гН3гН7aН9BН:⌠ О%EНБН/Н7Н2НUН#9Н&╩Н)█Н+ФН1,Н6Н:⌠ О#²НБНеНЮНXНЫНаН$÷Н'9Н*kН,2Н0⌡Н3┌Н8nН;╦Н<ЗН@eО!ЖНБН=НЇ НlНфН!JН%Н*√Н/├Н3эН67Н;Н@eО OНБНCНлН{НэН╣Н)Н ЦН#CН+Н-ЖН0ЭН2iН7║Н9·Н;ЧН@pОїНБНAНQНдН}НэpОXНБН#qОНєН°НэН&НAН!Н#YН'╗Н+ВН.5Н0ЛН4>Н5уН6щОaНБН НеН uН#/Н$тН'a Н.JН3ГН6║Н8МН=JО╨НБН▄Н║Н╒НKНі Н!eН$їН&[Н(1Н,┤Н1lН5Н8бН=.Н@-ОНБН=Н(Н▌НpН#Н(.Н-╡Н/ҐН2хН5щН9█ОkНБН[Н⌡НН"ВН)+Н,Н/^Н2ГН4ІН7+ Н>=Н?ЎОдНБНUНННoНжН!БН&1Н'[Н+%Н1├Н4TН9ЇН<Н@eОНБНU Н-ННrНNООН╞Н"▓Н$┬Н&ЬН*Н-)Н1 Н3ЯН6╠Н9МН<⌠Н>┬ОuНБН Н^НyНУН3НVН▀ОН ыН#ґН*$Н.÷Н1G*TVm$#COMMONMBUSSPECIFICATIONS9MapRefDirty{10}Thiscommandisusedbythemasterduringthefirstcycleofavirtual-to-physicalpagetranslationtransaction.Useofthistransactionindicatesthatthemasterintendstowritedatainthereferencedpageofitsvirtualaddressspace(eachmastermaybeoperatinginadifferentvirtualaddressspace).InthatfirstcycleMAddr[7..32)containsavirtual512-byte-pagenumber.Thefinalcycleofthetransactionisthecycleinwhichtheslave(map)assertsaDonecommandthatcontainstheresultsofthetranslationinMAddr.IORead{4}ThiscommandisusedbyamasterduringthefirstcycleofanIOReadtransaction.MAddrcontainstheIOregisteraddress.Thesecondandthirdcyclesareidle.AnynumberofdevicesmaygeneratesideeffectsinresponsetoanIORead,butexactlyoneslavemustassertdataonMDataduringthefourthcycle.TheinterpretationofanIOReadisentirelyuptotherespondingdevice.Thusitmayactuallyreadfromarealdeviceormaycausesomesideeffect,orboth.IOWrite{5}ThiscommandisusedbyamasterduringthefirstcycleofanIOWritetransaction.MAddrcontainstheIOregisteraddress.ThemasterassertsthedataonMDatainthenextcycle.Anynumberofslavesmayrespond,buttheydosoundetectedbytheIOWriteprotocol.IOReadFlow{8}ThiscommandisusedbyamasterduringthefirstcycleofanIOReadFlowtransaction.MAddrcontainstheIOregisteraddress.TheslavesignifiesreadinessbyaDonecommand,andassertsdataonMDatainthefollowingcycle.IOWriteFlow{9}ThiscommandisusedbyamasterduringthefirstcycleofanIOWriteFlowtransaction.MAddrcontainstheIOaddress.DuringthesecondcyclethemasterassertsdataonMData.InsomesubsequentcycletheslavesignifiesreadinessbyaDonecommand,andthemasterre-assertsthesamedataonMDatainthefollowingcycle.Done{14}Thiscommandisissuedbytheslavedevicetoflow-controlaMapRef,MapRefDirty,IOReadFlow,orIOWriteFlowtransaction.ThevaluethatitassertsonMAddrdependsonthetransactionandtheslave.IfthetransactionisMapReforMapRefDirty,thentheslaveisthemap.MAddr[0..25)containsthenumberofthe512-bytephysicalpagecorrespondingtothevirtualpagethatinitiatedthetransaction.MAddr[25..28)carriesoneofthefollowingorders:NoClear{7}--noactionrequiredFORINTERNALXEROXUSEONLYqОgНЮrН чОgОgН!╨qН&ОgОgН'ФrН(нОgОgН)ЁqН+&ОgrОgН+МvОgНEиpО_,НБ Н3qО[щНєН°НэН&НAН!Н#YН'╗Н+ВН.5Н0ЛН4>Н5уН6щОZ6НБН НеН uН#/Н$тН'a Н.JН3ГН6║Н8МН=JОX▌НБН┘НВНЯН■НХ Н!║Н$эН&┼Н(YН,╗Н1┤Н51Н8пН=5Н@-ОVГНБН=Н(Н▌НpН#Н(.Н-╡Н/ҐН2хН5щН9█ОU@НБН[Н⌡НН"ВН)+Н,Н/^Н2ГН4ІН7+ Н>=Н?ЎОS≤НБНUНННoНжН!БН&1Н'[Н+%Н1├Н4TН9ЇН<Н@eОQЯНБНA ННЄpОN╒НБНqОKSНєННшНєН!>Н#≤Н% Н)НН.ҐН1zН4╠Н8┌Н:≥Н<ГОI╛НБНйНгН!3Н# Н%©Н*╔Н0|Н3\Н7ЖН:ІН>'ОHНБННyНbНtНН"аН%╙Н+Н-яН2Н3 Н9%Н:╧Н<▐ОF]НБНcНН╚НН{Н#EН&JН(QН-Н1tН3тН8ОCБНєНy ННлН ╧Н%НН'WН,SН.cН0Н2k Н9┘Н>═ОB;НБН8Н<НSНmНтНЧН"ЄН&ЫН(ҐН+аН/vН3 Н5АН:Н;иpО>ЛНБНhqО;²НєННяН∙Н!*Н#Н%Н)кН.■Н1MН4~Н8JН:\Н<╔О9ЖНБНъНФН!\Н#нН%ЭН*МН0ьН3бН8EН<їН?О8NНБНЩНдН┤НШНН!≈Н$╞Н)ПН+ЎН/ҐН2жН8┘Н;Н>?Н@ZО6їНБ НКНФНFНЎpО3XНБ НЕqО0 НєНЮНdНРН QН"oН#╪Н(OН,БН/dН2_Н5УН7пН9Ц О.bНБНлНйН!7Н#÷Н%еН*╛Н0┘Н3fН6жН<,О,╨НБНчННрН▀НCН#▓Н&≈Н(²Н-PН.ЧН1^Н7ppО)kНБ Н?qО&НєНшНZНЦН =Н"VН#²Н(+Н,╨Н/7Н2-Н5ҐН7■Н9╒ О$uНБНыНчН!QН#юН%ЛН+рН0╙Н3Н7╩Н;>Н=ўО"нНБН4Н<НEНзН╛Н#B Н*oН-ЕН0GН3╠Н9Н>УН@ТО!'НБНёНSННWН"Ґ Н(іН*ЭН.pН1kН3hН8Н9ІН<ОНБpО0НБН└qОАНєН3Н НЙН"┐Н$СН'хН+єН0^Н2┌Н:╦Н╛ОpНБН┬ННtН$╣Н&┐Н(ВН.іН4 Н7dН@oОиНБНAН°НБН╠Н!Н#tО NНєНЕН?Н!КН#єН&Н,О рНєН6НкНBНIН!arОН ыН#ґН*$Н.÷Н1GЙTVm$≈COMMONMBUSSPECIFICATIONS10ClearRPDirty{6}--writepermissionforthecurrentphysicalpageissummarilycancelledinallcaches.Fromthispointon,anycachewishingtowritetoavirtualaddresslyinginthisphysicalpagemustacquirenewpermissionviaMapRefDirty.ClearVPValid{4}--virtualmappingstothecurrentphysicalpagearesummarilycancelledinallcaches.Fromthispointon,anycachewishingtoreferencethisphysicalpagemustacquireanewvirtual-physicallinkageviaMapReforMapRefDirty.WriteProtectFault{2}--aMapRefDirtyfailedtoacquirewritepermissionfromtheslave.ThisorderisofinterestonlytotheMbusmaster.PageFault{1}--theslavefailedtolocateavalidvirtual-to-physicalmapping.ThisorderisofinterestonlytotheMbusmaster.MAddr[28..32)carriesagroupoffourflagsfromwhichthemastercacheshouldupdateitsmappinginformation(exceptifthereisaPageFault):MAddr[28]--reservedMAddr[29]--writeprotect(=NOTdirty)MAddr[30]--dirtyMAddr[31]--referenced(=true)(Note:Theseflagsareallredundant.Theycanbeinferredfromthetransactionanditsfaults.TheyareincludedforbackwardscompatabilitywiththeESScache.)IfthetransactionisIOReadFloworIOWriteFlow,andtheslaveisnaive(ignorantofmapping),duringtheDonecyclethefieldMAddr[25..28)carriestheorderNoClear.IOdataisthentransportedinthefollowingMbuscycle.IfthetransactionisIOReadFloworIOWriteFlow,andtheslaveissophisticated(awareofmapping,probablythemapitself),thenMAddr[0..25)cancontainthenumberofa512-bytephysicalpage,andMAddr[25..28)cancontaintheordersNoClear,ClearRPDirty,orClearVPValid.IOdataisthentransportedinthefollowingMbuscycle(eventhoughthatdatamaybemeaningless;theIOReadFloworIOWriteFlowmayhavebeenexecutedforthesideeffectsofitsDonecommand).Infact,themapwillprobablycontaina"Donereflector"IOregister,thatwillsimplysavethedatasentbythemasterinanIOWriteFlowtransactionandretransmititintheappropriatefieldsoftheDonecommandthatterminatesthetransaction.Reserved{6,11,13,15}Thesecommandsarereservedforfutureuse.Cachesbuilttothisspecificationwillignorethem.3.3TheCacheConsistencyProtocolThecacheconsistencyproblemistopreventmultiplecopiesofadatumindistinctcachesfromhavingdifferentvalues.ThisproblemarisesbecauseDragoncachescontainshareddatathatmaybewritteninto.ThesolutioninvolvestheuseoftheMnSharedandMnAbortbuslinesandtwoadditionalbitssharedandownerstoredwitheachquadinacache.ForagivenFORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНEqО_'НєНDНеН(Н!▓ Н(mН*√Н,БН1≈Н6пН:Н;ZО]НБНЦН■Н├НЇН!▐Н$3Н'уН*6Н,ыН0╗Н5╣Н7fН:ФН<≈Н=цО[ьНБНлН>НЛН█Н шН$!Н'┼Н,iН/W Н6GН8└ОY]НєН7Н╛НН"=Н(]Н)КН,*Н0тН6Н9'Н;ZОW╣НБН НЮНЫНvН"tН%>Н)Н+█Н.WН2LН7Н9VН?|ОVНБНуНаНнН"RН$!Н'╣Н1ВН7dН:FН@ZОTgНБОQЛНєНфНIН ґН!д Н*EН.Н/ёН4pН7з Н>ЇОPDНБНAН└Н·НSН©НxН$WН'qН)Н+~Н-YН/ООMиНєН-НжН`НрН"LН&5Н'ЖН,Н-=Н0ЇН<ОL"НБНЭН╠ННуНЄН нН"}Н$эН&ІН)MОIїНєНтНН 4Н$%Н%мН(©Н+ИН/>Н3;Н5┴Н9ГН=╒ОGЪНБНuНOН Н"∙Н'_Н(©Н,IН-ЄН.ч ОE└НєН©Н6ОC НєН©Н6НЄН"]Н#ZН%?Н(АО@▌НєН©Н6О>НєН©Н6 Н ШН!ЬН#щrО;≈Н$НаНН╦Н╙НM Н%zН(dН*┐Н,&Н0qН3@Н5< Н:ИН=+Н>ҐО9ПНБНІН▓ННБНCН& Н(°Н*┌Н,ЦqО7uНєН~Н6 Н┼НN Н'АН)ЩН3*Н69Н8ЯН<╟Н>uО5мНБНУНоН}Н"Н$▐Н({Н,Н.▐Н1АН;CН?ЎО4&НБН≈НН!Н&Н▒Н"╦ Н*Н+╞Н.Н4!Н5ШН8▓О1╚НєННe НPН╛ Н%жН'┼Н0NН2УН5EН8°Н9ВО0НБН│НiН╚Н!╛Н$;Н'└Н+АН/6Н7ЖН:╟Н?ЎО.\НБНLНCН╚Н└Н#Н&ЛН)АН3aН6*Н;GН=ЕО,╣НБН'Н▐Н ўН*СН-jН0йН2░Н6 Н=╣Н?ЎО+НБНЕН╠Н8Н°Н MН$РН'╠Н*їН-°Н/~Н7⌠Н9Ц О)fНБН≈ ННЗН2Н"│Н(/Н*]Н,ўН/xН3╧Н5dН70Н:ЛО&КНєНwН─НЦНН╠Н$┤Н)jН*≤Н/ Н5EН7fН<═Н?sО%DНБН1ННTН8НШНвН"Н&eН'СН)ц Н2 Н8ЗН;▒ О#°НБН8НФНF Н╔НZН!Н#rН'=Н-·Н0l Н7Н9zpО NНБН┬НфНН@qОЪНєНёН┤НьН$OН&┼Н*╛Н-ЬН2╘Н5ОН7⌡Н::ОWНБН█Ня{О█НБННЬН& Н╨qО>НєН╠Н╡ Н Н%сН'sН)WН.▄Н4;Н8·Н:▄Н;КН@pО≈НБНоН7НІН IН&Н+@Н.rН4Н7ЕН=ОПНБН2ННwН|Н"JН%NН'?Н+РОtНєНnН╒НКН!=Н#єН%OН'║Н.XН1Н7Н9⌡Н<хН?rО мНБ НpНFО мО мНйqО мН╠pН▌О мО мН ?qО мН#ўН'ВН+7Н.▌Н23Н4Н5VН:IН=Н>jrОН ыН#ґН*$Н.÷Н1GАTVm$ОCOMMONMBUSSPECIFICATIONS11quad,ifsharedisfalsethennoothercachecontainsacopyofthequad.However,ifsharedistrueothercachesmayormaynotcontainthequad(thereisuncertaintybecausewhensharingstopsthisfactisnotdiscoveredimmediately).Owneristrueifandonlyifthelastwriteintothequadwasintothisverycache.AcacheinitiatesaReadQuadwhenitgetsamiss;itissuesaWriteQuadwhenaquadneedstoberemovedfromthecachetomakeroomforanotherquad(onlyquadswithownersetneedtobewrittenbacktomemory);anditissuesaWriteSingleandsetsownerwhenitsprocessordoesawritetoaquadthathassharedset.WhenacacheissuesaReadQuad,WriteQuad,orWriteSingleallothercachesonthebusmatchthequadaddresstodetermineiftheyholdacopyofthequad.AnycachethatmatchesassertsMnSharedtosignalthatthequadisshared.DuringReadQuadsthemasterandallmatchingslavescopythevalueofMnSharedintothesharedbitforthatquad.Also,whenacacheissuesaWriteSinglethemastercopiesthevalueofMnSharedintothesharedbit.Thisensuresthatsharingisdetectedassoonasitstartsandiseventuallydetectedwhenitstops.DuringReadQuad,WriteQuad,orWriteSingle,allmatchingquadsexcepttheonesupplyingdatatothebusloadnewvaluesfromthebusandcleartheirownerbits.Theownerbitisseteachtimeaprocessorwritesoneofthewordsofthequad.Ifthequadisshared,theresultingWriteSinglewillupdateallothercopiesofthequadandcausetheirownerbitstobecleared.Thusatanytimeatmostoneofthecacheswillhaveownerset.Ownermaynotbesetatall,ofcourse,ifthequadhasnotbeenwrittenintosinceitwasreadfrommemory.DuringaReadQuad,iftheownerbitissetonamatchingquad,thatcacheassertsMnAbortandsuppliesthedatatotheMbusitself(sincethememorydoesn'tknowthecurrentvalue).OtherwiseMnAbortisnotsetandthememorysuppliesthedata.3.4HousekeepingoperationsWeareleftwithtwoproblemsthatDragonsandprobablyCmachineswillhavetodealwith,andthatthatthebasicMbusoperationsabovehavedealtwithincompletely.Thefirstiscontextswitchesbetweenaddressspaces.Whenaprocessormovesfromoneaddressspacetoanother,alloftheoldvirtual-to-physicalassociationsinitscachesthatarenotalsopresentinthenewaddressspacemustbebroken.TherearetwowaystosolvethisproblemwiththebasicMbusoperations.First,theprocessorcanissueasequenceofPbusreferencesthatvictimizesalldatainallitscaches.Second,asequenceofMbusDonecommandscanbegenerated,incooperationwithasophisticatedslave,toclearVPValidinallcachesforallphysicalpagesthatmightbeknowntotheprocessor.Bothofthesesolutionsaresoexpensiveastoprohibitfrequentcontextswitchesbetweenaddressspaces.Thesecondremainingproblemismultiportmemories.Somememorieshavetwoports,aprimaryonewhichattachestotheMbusandasecondaryonewhichdoesnot.SuchamemorymightappearinadisplaycontrollerthatcandoautonomousBitBlt,forinstance.Whenbothportsareactive,ourprotocolformaintainingconsistencydoesnotwork,becausethesecondaryportcandoreadsandwriteswithoutinformingtheMbus.Apartialsolutiontothesecondproblemistotime-multiplextwo-portmemoriesamongseveralaccess-limitedstates.AtanymomentsuchamemoryisinoneofFORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНEqО_/НБНЇННzНДНН 7Н";Н%ыН)ёН/Н0-Н3}Н54Н7▓Н;ИО]┬НБН<Н НЪНэНtН ҐН#╨Н%wН(tН*БН/╨Н2Н5┼Н9├Н:Й О[ЮНБНН╪Н▒Н Н"ЁН%aН&нН)E Н0Н9FН=мН?:ОZ9НБНCНЗННuНтНTНрН"╙Н% Н(┬Н+4Н.Н0ґН3╪ОWЎНєН2НН$НPН$8Н'ОН)GН,Н-CН0ьН20Н6Н7?Н>iОVНБНН≥Н│Н6Н.Н ЕН$SН&╨Н*█Н,CН/ЧН3ўН5СН;Н>▀ОToНБНфНбНпНнНН ⌡Н"lН'Н*(Н+ЇН1ЬН4░Н5гН9┴Н:⌠ ОRхНБН█Н!НBНКН╧Н#юН&ЦН(Н+rН-Н.1Н1ёН4eН6мН;&Н>ОQ НБННЕНлНЭН A Н'гН)▒ Н1"Н3Н6ЎН;Н=!Н?┤ОOyНБНН~ННЧН╧Н&GН'ЁН*оН.Н/BН2═Н4eН6пН;BН>RОMрНБН⌡НсНН!╩Н#TН')Н)БН,,Н/■Н0ЙН6Н:ЄОL*НБНGН╪НyНnН qН$aН'╦Н*Н-лН/┼Н6TН91Н;√Н@ОJ┐НБН НОНJНрН┤Н ╡Н$~Н(_Н)┼ Н1Н3uН7ЕН<Н>tОHэНБН∙НTН'Н─Н ЮН#нН&БН+фН.▌Н3\Н4бН:7Н;ъН?Н@хОG4НБНvН-Н≥ Н1Н"╛Н&aН'ЇОD╧НєН─Ня Н%dН';Н/1Н14Н7EН;[Н?ЎОCНБН≤НМНЭНЄНН!ЎН$вН'оН,Н/xН1БН4┌Н7DН:÷Н=ПОAkНБО>ОНєНsН≥НґНН%Н!NН$kН%▄Н+≈Н/▒Н24Н3ДН6<Н:@Н;ЯН>HО=HНБНwНЙН|НШНлН?Н$Ь Н,√Н/TН3ШН5ЧН9╟Н=РН?ЎО;║НБНXНН╣НСН Н"╡Н$XН&AН+йН/@Н0пН3hН6├Н8Н;jН>Н?ЎО9ЫНБН0НьННGН ;Н$ЎН'юН*2Н, Н.:Н/пН2Н3лН8rН9пН<-Н?╘О8RНБНWНЄНgН?Н╡Н!Н#ЁН&нН*5О5вНєН⌠НЦНGН нН#TН'їН)КН+}Н-юН/ЛН1<Н7`Н;]Н>RО40НБН Н.НтН!Н#_Н&SН'ЯН*?Н, Н.▌Н1зН5╣Н8Н=`О2┬НБНЁН$НЪН!Н%╣Н+ЕН-bН/ИН2Н4ЮН7QН<пО0АНБНA{О-▓НБННЧ qО*CНєННZН╪НцН[Н$PН' Н,zН/Н4эН6JН<@Н>вО(°НБНшННэНщНЖН!Н#╦Н'vН) Н,{ Н3sН7юН;QН?О&ТНБН НMННHН"ЬН(7Н-│Н2FН7Н;Н< О%MНБНЩН;НЎН─Н!Н"▓Н'мН)■Н+%Н-\Н/²Н:╣О#іНБН╣Н╣Н*НН≈Н1Н"#Н'Н(ОН+tН.┤Н3√Н7qН:ЧН=О!ЧНБНУНZНН├НFН тН#┤Н)Н,IН.╨Н2?Н4+Н6с Н>О WНБНAНSНщН9НaН$IН&Н'VН)К Н0lН39 Н9▌Н;}Н>│Н@.О╟НБНГНgНЎНН#%Н%Н'Н)мН-бН4рН7┤Н9╒ Н@pОНБ Н[НoН▒Н"╠Н&iН(Н+[Н0ьН2Н4hН8╠Н:ГН<пОaНБН▓НFН#НЫНdН ЬН#= Н)ВН-9Н.вН2FН7ЯН:*Н;сО╨НБН░Н>Н▄НН!ЯН'UН,цН1ґО>НєН■Н>НьН%uН&ЫН-1Н4┤Н8uН>вО≈НБН²Н┌Н╩НН╪Н"ыН( Н)щН,LН.5Н0шН3║Н4зН;UН>ОПНБНnНwНGНмН!√Н%ИН*лН,жН.\Н3j Н:Н=0Н@ОHНБ НЯН┌НН$╞Н) Н,┤Н0GН2щН7cН:0Н?АО║НБ Нf Н┤Н ╔Н#Н&лН+эН.)Н4┐Н7kН9ЕН;зН?gОЗНБНДНПН[Н ╨Н"■ОНєННOНyНН VН$пН*<Н+▐Н-% Н6RН;тО вНБН└Н1 Н!Н%мН'ЕН*╒Н0,Н3zН4юН:JН;рН=²Н@erОН ыН#ґН*$Н.÷Н1GЪRTVm$gCOMMONMBUSSPECIFICATIONS12threestates:eitheritssecondaryportisentirelyinactive,orelsetheMbushasnoknowledgeofit,orelsebothMbusandsecondaryportarepreventedfromwriting.Thissolutionisabittoocoarse.Wecanrefineitbyallowingeachpageinsuchamemorytobeinoneofthethreestatesindependentofthestatesofotherpages.TodealwiththefirstproblemweintroduceanoperationcalledDeMapping(breakingvirtual-to-realassociation,leavingorphansinthecache).TodealwiththesecondweintroduceLaundering(rewritingalldirtyquadstomemoryandleavingthemclean)andFlushing(clearingRPValid).(FlushingappearsnottobenecessaryifReadQuadsalwaysrefillcleanorphansfrommemory.LaunderingandDeMappingsufficeinthatcase.)Collectivelywerefertotheseashousekeepingoperations.Forefficiencyhousekeepingoperationsapplynottosinglephysicalpagesbutrathertosetsofphysicalpagesmatchingamaskof{0,1,don'tcare}"trits".Housekeepingoperationscanbeappliedtoallcachesatthesametime,ortoasinglecache.Eachcachecontainsapairof32-bitregistersthattogetherholdthephysicalpagemasktobeused.Inaddition,eachcachehasasinglehousekeepinginitiationregisterlocatedattwoI/Oaddresses:abroadcastaddress,andaprivateone.1bitsstoredintoappropriatebitsoftheinitiationregistercauseinitiationofDeMap,Launder,andFlush.(IfwecoulduseaddressesinESScachemailboxspace,therewouldbeawayofnotifyingprocessorsattachedtoESScachesthatthesehousekeepingoperationswerebeinginitiated.)ThisallimpliesthatacacheneedstorespondasaslavetoitsownIOWrites,andprobablytoitsownIOReadsaswell.Itisnotnecessaryforcachestorespondtoflow-controlledIO.LaundercanrequireenoughMbuscyclestotransportalldirtyquadsineverycachebacktomemory.WhileaLaundryoperationisunderwayeachcachere-arbitratesfortheMbusforeverydirtyquadthatitownsandneedstostore.RequestsfromthePbussidedemandingMbusservicehavehigherprioritythantheoperationrequests.Thesestipulationstogetherpreventahiccupfromoccuringinthesystemwhenthereisagreatdealofdirtydatatobelaundered.NotonlyLaundry,butallhousekeepingoperations,dependingontheirimplementations,maytakemanycyclestocomplete.Conceptuallyeachcachemaintainsahousekeepinginprogressbitthatindicatesthatahousekeepingoperationhasbeenstartedinthatcachebutnotyetfinished.WhetheranoperationisinprogressinanycacheinthesystemcanbeknownbyobservingthestateoftheMnHousekeepingInProgresswirefortwosuccessivecycles.Ifitisnotassertedinsomecyclei,thenanycachewithanoperationstillinprogresswillassertMnHousekeepingInProgressincyclei+1.Ifitisassertedincyclei,theneverycachewillde-assertitincyclei+1.MnHousekeepingInProgresswillthustoggleonandoffuntileverycachehasfinishedthelasthousekeepingoperation.EachcachehasameansbywhichMHousekeepingInProgress[i+1]ORMHousekeepingInProgress[i]maybereadfromitsPBuswithoutneedingMbuscycles.Thealertreaderhasalreadynoticedthatconcurrenthousekeepingoperationscouldbeanightmare.Weavoidconcurrencybymaintaining,asasoftwareconvention,aglobalhousekeepinglockinshared(andalwaysmapped)memory.Todohousekeepingaprocessmustacquirethelock,verifythatprevioushousekeepingisfinished,initiatetheoperation,and(iflogicallynecessary)holdthelockuntilhousekeepingisonceagainfinished.FORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНEqО_/НБНwН╡Н╚Н▓Н# Н&Н'┬Н,■Н2Н3чН6║Н9 Н:ТН=√Н@О]┬НБНҐНmННлНyН ╛Н"|Н% Н'ЇН.Н1 Н3SН9ЇН=О[ЮНБННHН╦НГН НxН#▀Н&Н(╚Н,іН.Н0Н5┼Н8©Н<Н=ЎН@ТОZ9НБНOНЧННН°НHНН aН#ЙН'÷ Н/▌Н1GН3їН7\Н9Н<ЄОWҐНєНЛННDНеН©Н%eН'ўН-ШН0 Н6XН:rОVНБНЧН⌡Н$кН){Н.╟Н0QН2ёН7╙Н9дН<╠Н?ЎОTnНБН├Н©НШ Н#w Н)чН+ЮН/DН3XН5Н:≤Н=aОRгНБН╦ННН Н&rН,ЎОRгОRгН-Н1СН69Н8nН:Н;оН@ИОQНБНнНPНТНнН"Н$ЇН)╨ Н/╔Н1оН7ПН;rН<хН?qОOxНБННмНюН Н$<Н&▄Н/м Н8⌡Н;И ОMяНБНЄ Н∙Н"⌠Н%;Н'Н+;Н0╪Н4╨Н7nН;╞Н=▒Н@eОL)НБНН╛Н┐Н├Н!РН#┐Н%≥Н&ЪН*lН-ДН2═Н;p ОJ┌НБНmН^НHНВНГН 7Н!оН$/Н'╛Н+*Н,НН.°Н/фН3╠ОHНєН;Н+НЁН Н"ЩН$зН(ЖН.}Н1pН6ЬН:MН<пОF_НБН*НЎНnН`Н{НKН%Н(FН,Н.┼Н/╣Н3║НOН?|ОCНБНEН] НЭН чН"вН%v Н+▓Н0╟Н4╔ Н:бН<╨ОAiНБНюНnrНОAiОAiНxН╔НWН"XН$HН)Н*mН,гН/хН3ЧН74Н:Н=QН>вН?ҐО?аНБН(НҐ НИН1НnН!╣Н%Н'2qН)КО?аО?аН*╡ rО?аН2U Н7▓Н:Н= qО=EНєНнНнНіН┘НЎН# Н'▄Н)JН.²Н0[Н1∙Н5Н6йН8╣Н;иО;·НБН НlННЖНШН#ЇН%eН)0Н*╗Н,Н.┼Н4·Н6эН;-Н<эО9ЖНБН░Н!О7zНєН4НаН▀Н#wН%RН'ЙН+ЦН-⌠Н3qН5cН8ІН<╨Н>jО5сНБНН╡Н©НдН$;Н%цН+╪Н2DН4Н:бН>RО4+НБН╡НН√Н■Н OН"╟Н&┬Н)ЩН-═Н0▓Н2Н5╦Н8⌠Н<≤Н>jО2└НБНсНNНбН,НжН!цН(ЧН*ЛН-≈Н21Н5▄Н9ОН>ЬО0щНБНFНtН╡Н!╦Н)Н.nН3sН4║Н9Н<┐О/5НБН░НПНkН Н╘Н Н!>Н$╠Н'╙Н)cН,╣Н/╨Н1hН3Y О,╧НєНСН▄НЩН!ЩН$lН-┴ Н5НвО+НБНИН8Н ~Н$■Н(вН*яН2,Н:уН>RО)kНБНpН)О)kО)kНЕ НdНЫqН%)О)kО)kН%ПН'5Н)РН/▒Н2NН3gН;ТО'цНБН─НН╙Н│НxН"mН%Н'╣Н*&Н0√Н6pН8┴Н>шН@pО&НБНvНKНННзН!`Н&Н(ЄН*лН/xН1⌡Н8Н:┤Н=ъН?ЎО$uНБН LН#qН%фН(┴ Н/Н4 Н5іН7Н8√Н;"Н@pО"мНБНКНтН┴Н%Н<Н#~Н'Н)tН0Н3*Н5NН;2Н>SО!&НБН aН";Н%зН*Н+╣Н-7Н.оН42Н6Н9╛Н;Н>jОНБНіНJНТНBНИН!UН%Н6eН9 Н<Н@ОвНБН⌡НнННлН≥Н!Н&SН(ЄН+5Н3у Н:чН>RО0НБНЕН²НoН"ЬН)■rН?ИО0О0Н@фqО┴НБН йН$Н&$Н)qН- Н/Н2сН8Н={Н?┤ОАНБОeНєН НщН@НсН#еН(бН+╞ Н2ЁН;p ОЎНБННeНР Н!Н"Н&1 Н.WН0ІН9Н;Н<╔ОНБ Н7НMН[Н#ФН&кН(eН,ІН/сН4#Н9жН?ВОoНБНБНzН·НkН"мН'іН)ЪН-JН1/Н3ЖН9ОхНБН─НMННў Н$bН'LН)XН.Ь Н5ЇН9Н;╛Н>вО НБН│НЛН3НэrОН ыН#ґН*$Н.÷Н1GTVm$JCOMMONMBUSSPECIFICATIONS134.BusTimingThissectiongivesthedetailedtimingofbusarbitrationandofeachofthetransactionsjustdescribed.Inthetimingdiagrams,eachrowcorrespondstoonebuscyclefornon-idlecycles.Idlecyclesarerepresentedbyarowlabelled"wcycles",wherewindicatesthenumberofidlecycles.ActionsduringeachcycleareindicatedusingMesalikestatements.NotethatthebooleanvalueTRUEcorrespondstothehighvoltagelevelandthebooleanvalueFALSEcorrespondstothelowvoltagelevel.Forexampleanegativelogicsignalxwouldbeassertedasfollows:x_FALSE.ThediagramsdonotdescribethetimingofMParity,sincethisisalwaysonecycledelayedfromthevalueonMTransport.Ineachdescription,therequestorassertsMnRqincycle0andthearbiterassertsMnGntincycle1.Anarbitrarynumberofcyclesmayoccurbetweencycleslabelled0and1.4.1ArbitrationThetimingforarbitrationappearsinFigure2.ArequestorassertsMnRqduringphaseAofcycle0.ThearbiterlatchestherequestduringtheBofcycle0,andifthebusisfreeMnGntgetsassertedintheAofcycle1.Thenewmastercandrivethebusatthebeginningofcycle2A.Thustheminimumarbitrationdelayistwocycles.Ifthebusisnotfree,zeroormorewaitcyclesareinsertedimmediatelyaftercycle0.TheearliestMnRqcanbedeassertedisduringcycle2+w.TheearliestMnGntisdeassertedinresponseisduringcycle3+w,andtheearliestanewdevicecanbecomemasterisduringcycle4+w.TheearliestMnNewRqmaybeassertediscycle3+w.Itmustbedeassertedinthefollowingcycle.4.2ReadQuadFigure3showsthetimingforReadQuad.Cycles0through1aretakenupbyarbitration(recallthatweareassumingtheminimumarbitrationdelay).Thetransactionbeginsincycle2.ThemastersetsMCmdtoReadQuad,MAddrtoRQAddress,andassertsMnAdCycle.Cycles3and4donottransmitanydata.Duringcycle3themasterdeassertsMnAdCycleandduringcycle4anymatchingcacheassertsMnShared,andifitsownerbitisset,assertsMnAbort.InthefollowingcyclememorydeassertsMnSharedandthecache,ifany,thatassertedMnAbortdeassertsit.Aftercycle4theslavemayinsertanarbitrarynumberofwaitcycles,w>0.Incycle5+wtheslave(respondingcacheormemory)assertsMnDVtosignalthatdataisvalidandsendsthefirstwordofthequadonMData.Duringcycle6+wtheslavedeassertsMnDVanddrivestheseconddatawordontoMData.Duringcycle7+wtheslavedrivesthethirddatawordontoMDataandthemasterdeassertsMnRq.During8+wtheslavedrivesthefourthdatawordontoMDataandthearbiterdeassertsMnGnt.NotethattheminimumnumberofcyclesforReadQuadis7,assumingzeromemorywait.FORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНEzО^УНБНЎН qО[іНєНПНюНdНЖН%aН)МН+ыН.╒ Н5≥Н8┐Н:oН=сН?ЎОYЪНБН─Н@ Н ┌Н"pН$МН)fН/╦Н3Н5Г Н=іН?rОXWНБН═Н;Н═Н@Н"bН&Н*-Н,╗ Н4:Н6]Н7╞Н:≤Н?КОV╟НБНщНПНmНН!tН&⌡Н(OН+Н/йН4еН90Н<\Н?йОU НБНЎНOНЮНt Н%ыН)7Н+НН.5Н3SrН6ЕОU ОU Н7·qОU Н:} ОSaНБН|НгНьН─Н╡Н TН"÷Н'аrН+VОSaОSaН,qОSaН/d Н6ПН8┼Н:уН=aОQ╨НБНbН=НЕН>Н"шН&[pН*vОQ╨qОQ╨Н+ПН0NН2nН7тН9╠pН?ОQ╨qОQ╨Н@▒rОPНБqН─ОPОPНННН1Н!дН'EН)цН.;Н0Н5ъН9pН<0Н=╧ОNkНБН▌ННН~НщН#┤Н%█ ОKПНєНYНpНаН Н&Н*6Н.█Н0!Н3zН4∙Н72Н9xН=оОJIНБНмНgНеН╛НКН"{Н'⌠Н)7Н-Н0 Н3╣Н9Н<РОH║НБННн{ОC╙НБН qОA/НєН╣НHНЎ Н"╪Н(Н)ГН.░Н1Н2ьН9%Н=ґО?┤НБНUН9НхН┐НЬН Н"ХН'[Н+ЕН.FН3Н7░Н9РН;`Н=Н@▒О=ЮНБН▒НХН?НмН0НТН КН#╞Н(чН*┐Н,зН.]Н0Н3xН5wН8FН;+Н?⌠О<9НБНuНчНН!Н▀Н"Н#цН'@Н)ъН-gН/пН60 Н<ЧН@╡О:▒НБН┤НLНгН Н╟НН ┐Н#║Н&²Н(ZН+ФН.ыН2иН5Н:F О8ЙНБНН▒О6oНєНjН НiНБН!а Н(SН)ґН.Н1lН5ЇН8~Н=О4гНБНq Н8Н НрН aН$УН(▀Н,≥Н/tН1ВН6лН8Н;+Н?⌠О3 НБНН╗Н4НдН"WН'Н)ЧН.пН6'Н9JН;[Н@╡О1yНБНUНдН;НёН■ Н$8Н%ФН(EН.X{О,┌НБНqО*НН├Н╠Н╣НН"]Н$▒Н,@Н0▓Н1ҐН6ЛН8Н:bН>Н@"О(_НБ НіНтНёНйН!Н'Н)zН/п Н6■О%ЦНєН` Н?НrН!Н$[Н&3Н(ОН-DН/иН4uН6Н=)О$<НБН÷ НpН6Н■ Н(OН,╦Н-ЭН0бН2Н4Н6÷Н<Н>аО"∙НБНбНKН≈Н Н■Н%fН->Н0Н4⌠Н8Н9hН< О МНБН▓НеНфН aН!іН#dН'vН)wН*гН- Н1SН8Н9хН<ОFНБН┤Н&НН% Н'РН*└Н.ыН0lН3≈Н6≈Н;ЪО÷НБН╘НСН²НН\Н!гН%:Н(IН, Н.Н3мН9Н:иН=нpОВНБ|НиОВqОВН#О|НєНvНМН└НГН R Н'КН+╩Н-┌Н3lН7©Н<─Н>3ОуНБНпНТНННщН ╪Н#;Н&2Н)зН+ЁН.1Н1оН3УН9цН>╚О-НБНЁНQНЖНПН#ЛН&БН+-Н-кН2⌡Н5чН9╔Н=О├НБН╗НН╘НН jН$tН&яН*6Н-9Н0ЎН3ЛН8°Н;QН=ўОъНБН╠Н$НН"іН%Н(⌠Н,ЁН/&Н3sН6▀Н:'Н=kО7НБН≥НЫНiН%О╪НєН;Н*Н╙Н! Н&mН(FН,^Н.╪Н5цН7OН8ЩН?О НБНOОmrОН ыН#ґН*$Н.÷Н1GЪ TVm$vCOMMONMBUSSPECIFICATIONS144.3WriteQuadFigure4showsthetimingforWriteQuad.Cycles0through1aredevotedtoarbitrationasusual.Duringcycle2themastersetsMCmdtoWriteQuad,MAddrtotheaddressandassertsMnAdCycle.Duringcycle3themasterdrivesthefirstdatawordontoMDataanddeassertsMnAdCycle.Duringcycle4themasterdrivestheseconddatawordontoMDataandiftherearezerowaitstates(w=0)thememoryassertsMnDV.Duringcycle5themastersendsthethirddatawordonMDataandiftherearezerowaitstates,deassertsMnRq.ThememorydeassertsMnDViftherearezerowaitstates,orassertsMnDVifthereisonewaitstate.Incycle6themasterdrivesthefourthwordontoMData,anddeassertsMnRqifthereisonewaitstate.IftherearezerowaitstatesthearbiterdeassertsMnGnt.ThememorydeassertsMnDVifthereisonewaitstate,orassertsMnDViftherearetwowaitstates.Incycle7,iftherearetwowaitstates,themasterdeassertsMnRqandthememorydeassertsMnDV.IfthereisonewaitstatethearbiterdeassertsMnGnt.IftherearethreewaitstatesthememoryassertsMnDV.Finally,thereareanarbitrarynumberofwaitcycleswhichareterminatedbythememoryassertingMnDV,followedinthenextcyclebythemasterdeassertingMnRq,andinthenextcyclethearbiterdeassertingMnGnt.NotethattheminumumnumberofcyclesforWriteQuadis5.4.4WriteSingleFigure5showsthetimingforWriteSingle.Cycles0through1aredevotedtoarbitration.Duringcycle2themasterdeassertsMnRq,setsMCmdtoWriteSingle,setsMnAdrtotheaddress,andassertsMnAdCycle.Duringcycle3themastersetsMDatatothedataanddeassertsMnAdCycle.ThearbiterdeassertsMnGnt.Duringcycle4anymatchingslaveassertsMnShared.Duringcycle5anymatchingslavesdeassertMnShared.4.5IOReadFigure6showsthetimingforIORead.Arbitrationtakesplaceduringcycles0through1.Duringcycle2themasterassertsMnAdCycle,assertsIOReadonMCmd,assertstheIOregisteraddressonMAddr,anddeassertsMnRq.Duringcycle3,themasterdeassertsMnAdCycle,andthesingleslaveassertsdataonMData.4.6IOWriteFigure7showsthetimingforIOWrite.Cycles0through1areforarbitrationasusual.Duringcycle2themasterassertsMnAdCycle,assertsIOWriteonMCmd,assertstheIOregisteraddressonMAddr,anddeassertsMnRq.Duringcycle3,themasterassertsthewritedataontoMDataanddeassertsMnAdCycle.4.7IOReadFlowFORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНE{О_,НБНqО\╠НєНН^НvНЮН"EН$▌ Н,їН1Н2LН7▐Н8нН;-Н@oО[ НБ НіНUОX▌НєН▒Н(Н┌НН" Н%`Н*MН, Н3дН8щН:╟Н=4ОVГНБН÷НУ Н·Н#mН&ФН(!Н*┤Н.ЩН3Н5vН8TН;_Н>МОU@НБН┘Н-Ны Н$WН)Н,tН-≥Н/ИН4JН8GН:≈Н?ОS≤НБНPНeНЩН НЮН!NН#┤Н&pН)NН,ИpН-bОS≤qОS≤Н.IН1=Н3┌Н8тН= ОQЯНБН·НН,ННЦН"√Н$ИН(DН+=Н.╧Н0╡Н5XН8Н9WН<тН?ОPJНБНСННЛН!gН$WН)эН/╞Н4┘Н5ЩН9·Н< Н?%ОN╒НБНЫНгННГНQН"ДН$YН'Н*Н.1Н0 Н3┤Н4еН7.Н;╗Н?ЎОLШНБН2НпНН7Н"Н'жН,\Н-сН1rН2ТН5╣Н8дН<ЩН>∙ОKTНБНCНTН[НН▀Н" Н'рН-иН0ўН6)Н;РН@ҐОI╛НБНtНИН·Н═Н3НН#XН(Н)┴Н-Н/xН2-Н5/Н9сН;╚Н?'Н@ҐОHНБН÷Н'НН4НvН" Н&ўН,²Н1BН4-Н6аН∙ОDІНБНЬНйНGНяН"=Н(Н-6Н0эН3LН5ZН;Н@eОCНБНЛНСННu Н#vН%┌Н'РН-pН3%Н8KН>Н?ЎОAhНБН@ННLНЗН╦ Н'Н,/Н/5Н12Н3ЮН7>Н:ЪН=ґО?юНБ НСО=EНєННХНHН!Н&-Н'ФН+чН.Н5CН6ў{О8NНБН qО5сНєННPНaНдН""Н$cН,яН1/Н2hН7єН8эН;4Н@oО4,НБН|НBН╡НДН"@Н&ўН,fН1,Н3йН8░Н:;О2└НБН─НqННxНЇН"kН&Ї Н/MН4Н7┌Н8ЄН;Н?}О0щНБН|ННXНDНЦН"├ Н*ЯН-╟Н2Н7╚Н=UО/6НБНbНёНPН[НоН$*Н+ДН0╨Н49Н5zН8(Н>3О-▌НБН{О(≤НБНqО&НєННEНPНўН"Н$BН*Q Н1vН4РН8┘Н<ТН@ИО$uНБНО!ЗНєНQН╘НцНН!\Н%░ Н-▌Н1бН6чН8иН=оО SНБН5НDННСНЛН$,Н&вН,├Н1╦Н6uН9шН;[Н=ўО╚НБН· НЇНoН!нН%╧Н) Н-oН0tН2{{О╣НБНqО:НєННOН_НаН"Н$_Н*╨Н/Н0OН5┼Н6бН9Н;Y О▓НБН░ОНєНKН²Н╠НОН!>Н%l Н-eН1⌠Н6ЙН8оН=оОpНБН5НDННСНЛН$,Н&вН,├Н1╦Н6uН9шН;[Н=ўОхНБН1Н▒НННCН#ЖН&ўН,i {О рНБН rОН ыН#ґН*$Н.÷Н1G4TVm$ыCOMMONMBUSSPECIFICATIONS15Figure8showsthetimingforIOReadFlow.Cycles0through1areforarbitrationasusual.Duringcycle2themasterassertsMnAdCycle,assertsIOReadFlowonMCmd,assertstheIOregisteraddressonMAddr.Duringcycle3themasterdeassertsMnAdCycle.Followingcycle3therecanbew>0waitcycles,duringwhichtheslavedoesnotassertMnAdCycleandMCmd=Doneduringthesamecycle.Duringcycle4+wtheslaveassertsMnAdCycle,setsMCmdtoDone,andsetstheordersfieldofMDatatoNoClear(othervaluesareacceptableiftheslaveisthemap).Incycle5+wthemaster(slave?)deassertsMnAdCycle.TheslaveassertsthedataonMDataandthemasterdeassertsMnRq.4.8IOWriteFlowFigure9showsthetimingforIOWriteFlow.Cycles0through1areforarbitrationasusual.Duringcycle2themasterassertsMnAdCycle,assertsIOWriteFlowonMCmd,assertstheIOregisteraddressonMAddr.Duringcycle3,themasterassertsthewritedataontoMDataanddeassertsMnAdCycle.Followingcycle3therecanbew>0waitcycles,duringwhichtheslavedoesnotassertMnAdCycleandMCmd=Doneduringthesamecycle.Duringcycle4+wtheslaveassertsMnAdCycle,setsMCmdtoDone,andsetstheordersfieldofMDatatoNoClear(othervaluesareacceptableiftheslaveisthemap).Incycle5+wthemaster(slave?)deassertsMnAdCycle,reassertsthewritedata,anddeassertsMnRq.4.9MapRefandMapRefDirtyFigure10showsthetimingforthesetwotransactions.Cycles0through1areforarbitrationasusual.Duringcycle2themasterassertsMnAdCycle,assertsMapRef(orMapRefDirty)onMCmd,assertsthevponMAddr[7..32).Duringcycle3,themasterdeassertsMnAdCycle.Followingcycle3therecanbew>0waitcycles,duringwhichtheslavedoesnotassertMnAdCycleandMCmd=Doneduringthesamecycle.Duringcycle4+wtheslaveassertsMnAdCycle,setsMCmdtoDone,andputsrp,orders,andflagsontoMData.Incycle5+wthemaster(slave?)deassertsMnAdCycle.FORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНEqО_/НєНfНМНLНЧН#╚Н&: Н/ЖН4╒Н6)Н;ЄН=;Н?АО]┬НБ НіНUО[НєНpНФНН│Н!ТН&G Н.dН2І Н:ТН<ЩОY_НБНiННTНkН"▄Н$кН+Н0Н3ІН5#Н7╨НсНБ|НЮО>сqО>сН:НЪН┴НjН kН% Н'ЗН+РН/ЁН2╧Н7Н?gО=,НБНмН╧Н ■Н$▄Н)яН/Н3Н7Н9ЛН=оО;└НБ ННхНіН jН$ёН'pН*'Н,°Н0ЙН40Н5ЪН:хН<▄О9щНБН,Н▄Н Н СН"┘Н%Н(╟Н*MН,чН1╡Н3ЁН7WН;Н=ўО86НБНкН┤ Н!═Н'Н)xН,ЖН0SН3Н8ф{О34НБННvН qО0ЁНєННННxН"жН%Н(іН+WН3╪Н8Н9TН>▒Н?йО/НБН НДН▓О,▀НєНMН║НЇНВН!HН%x Н-sН1ёН6РН9О*ДНБННIН╧Н9НTН!{Н+(Н0Н3╔Н5RН7рН╨Ч╚$Н#О;dН■О;dЧ╚$Н■О0HЧ╚$Н мО эЧ$▐Н#О2│НЙО5жЧ╚$НЙО/OЧ$╚Н■О/OЧ$╚НЙО/+Чн$НxО)² НЙО,РЧ╚$НЙО&kЧ$╚Н■О&kЧ$╚НЙО&GЧн$НЙО$Ч╚$НЙО┤Ч$╚Н■О┤Ч$╚НЙОcЧн$НxО ╧НxОC,Ч▐$Н■О ╧Ч]$НxО+Ч╡$Н%?О>╨Ч╚$Н%?О83Ч$╚Н+ЙО83Ч$╚Н%?О8Чн$Н&ЙО;СН&ЙО:HН%?О3²Ч╚$Н%?О-Ч$╚Н+ЙО-Ч$╚Н%?О,РЧн$Н&ЙО0жН&ЙО/+Н■О)²Ч9$Н■ОA│Н?ОЧ$.╛Н[ОEСН?ОG·Ч!V$Н?ОРЧ!z$Н2∙ОЧ$.╛Н2∙ОjЧ$rН2∙О©Ч$rН+ЙО;dЧy$Н/@О0kЧ$Н+ЙО0HЧy$Н/@О5жЧ9$Н2∙О─ЧД$Н2∙О уЧД$Н0\О]вЧ$Н;yО<│Ч╚$НEyО=НEyО;dНB$О5жЧ@$НMAО5ЗЧ$ VНB$О5ЗЧ$ VНB$ОC,Ч$Н;yО(─Ч╚$НEyО)НEyО'dНB$О!уЧ@$НMAО!ЫЧ$ VНB$О!ЫЧ$ VНB$О/+Ч$НDКО НDКОуН=$ОН?КОcЧ▐$Н?КО1Ч$ VНOzО1Ч$ VН?КОЧ╡$Н;yО╧Чr$Н$#О*rЬЗОН ыН#ґН*$Н.÷Н1GOTVm$=COMMONMBUSSPECIFICATIONS17Figure 2. Timing for Bus Arbitrationarbiter: latch request;4+w3+w2+w(w>=0)w cyclesABABABABAB0PhaseCycleBA<><>1+wrequestor: MnRq _ FALSEarbiter: MnGnt _ FALSE;<><>; MnNewRq _ TRUE;FORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНE}ЬЪЗЪНО)²П$~НЙОLЕНмО3аЧ$ :Н?О3аЧ$ :}Н [О7│Н [О;СН [О@e~Н?ОHsН╟ОJ}НО8²НО6dН ИО5жЧ:Е$НО=НО:жН ИО:HЧ:Е$НОA│НО?HН ИО>╨Ч:Е$НОEСНОC╨Н ИОC,Ч:Е$НОJeНОH,Н ИОG·Ч:Е$Н ИОLЧ:Е$Н [ОM╨Н[ОQ·Н ■ОSвЧ>;$Н ■ОP┌Ч>;$Н?ОQ·НОL·НОNв~НЙОAхНЙО8Д}НмОDв~НЙОOНЙОF:ЬЗН(ОAхП5ЬЪЗЪНЙО=VП3rЬЗОН ыН#ґН*$Н.÷Н1GЪfTVm$ИCOMMONMBUSSPECIFICATIONS18Figure 3. Timing for ReadQuad8+w7+w6+w32w cycles(w>=0)BABABA5+w1ABABABABABAB0PhaseCycleBArequestor: MnRq _ FALSE;arbiter: MnGnt _ FALSE;4slave: {MData _ RQData0; MnDV _ FALSE};AB9+wslave: MParity _ RQData3Parityslave: {MData _ RQData1; MParity _ RQData0Parity; MnDV _ TRUE}slave: {MData _ RQData2; MParity _ RQData1Parity} master: MnRq _ TRUE;w=0 => {some cache: owner => MnAbort _ TRUE; memory: MnShared _ TRUE}master: {MCmd _ ReadQuad; MAddr _ RQAddress; MnAdCycle _ FALSE}master: MnAdCycle _ TRUE;any cache: {match => MnShared _ FALSE; owner => MnAbort _ FALSE}; waitCycle _ 0;memory: MnShared _ TRUE}(waitCycle _ waitCycle+1)=1 => {some cache: owner => MnAbort _ TRUE; slave: {MData _ RQData3; MParity _ RQData2Parity} arbiter: MnGnt _ TRUE;FORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНE}ЬЪЗЪН!\О╦Н"О!уН"О&GН"О*╧Н"О@eН"ОDв~Н О7хН О6Н╟О)Ч?W$}НмО)²НмО+жН╟О$²Ч?W$НмО%+НмО'dН╟О +Ч?W$НмО ╧НмО"РН■ОЧ$:ЕНОЧ$:ЕН"О0HН"ОIHНмО2│НмО.Н╟О-─Ч?W$НмО8²НмО4╨Н╟О4+Ч?W$НмО=НмО:жН╟О:HЧ?W$НмОA│НмО?HН╟О>╨Ч?W$НмОEСНмОC╨Н╟ОC,Ч?W$НмОJeНмОH,Н╟ОG·Ч?W$Н╟ОLЧ?W$Н"ОM╨Н"ОQ·Н[ОSвЧBґ$Н[ОP┌ЧBґ$Н ОQ·НмОL·НмОNв~Н╠ОOН╠ОJ╛}Н"О;С~Н╠О2хП'}НмО─НмОGН╟О╧Ч?W$Н"Оc~Н╠ОгН╠О,П>Н╠О'╚ПGЬЗНЙО1ПEЬЪЗЪН╠ОF:П?ЬЗН╠ОAхЬЪЗЪН╠О=VПPЬЗНЙО7:Н╠О8ДПEЬЪЗЪН╠О#9ПHrЬЗОН ыН#ґН*$Н.÷Н1GTVm$XCOMMONMBUSSPECIFICATIONS19Figure 4. Timing for WriteQuadABCyclePhase0BABABABABABA1ABAB23requestor: MnRq _ FALSE;arbiter: MnGnt _ FALSE;master: {MCmd _ WriteQuad; MAddr _ WQAddress; MnAdCycle _ FALSE}4567master: {MData _ WQData0; MnAdCycle _ TRUE}w=0 => memory: MnDV _ TRUE; w=1 => memory: MnDV _ FALSE;master: {MData _ WQData2; MParity _ WQData1Parity; w=0 => MnRq _ TRUE}master: {MData _ WQData3; MParity _ WQData2Parity; w=1 => MnRQ _ TRUE}w=0 => memory: MnDV _ FALSE;master: {MData _ WQData1; MParity _ WQData0Parity} (w>0)w=0 => arbiter: MnGnt _ TRUE; w=1 => memory: MnDV _ TRUE; w=2 => memory: MnDV _ FALSE;w=1 => arbiter: MnGnt _ TRUE; w=2 => memory: MnDV _ TRUE; w=3 => memory: MnDV _ FALSE;waitCycle=w-2 => arbiter: MnGnt _ TRUE; waitCycle=w-4 => memory: MnDV _ FALSE;waitCycle _ waitCycle + 1; waitCycle=w-3 => {master: MnRq _ TRUE; memory: MnDV _ TRUE}w-1 cyclesmaster: {MParity _ WQData3Parity; w=2 => MnRq _ TRUE}; waitCycle _ 1;FORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНE}ЬЪЗЪН!\О°Н■ОNвН■ОL·НмОQ·Н"ОP┌ЧDФ$Н"ОSвЧDФ$Н ИОQ·Н wОM╨Н wОLЧA░$Н wОG·ЧA░$Н■ОH,Н■ОJeН wОC,ЧA░$Н■ОC╨Н■ОEСН wО>╨ЧA░$Н■О?HН■ОA│Н wО8ЧA░$Н■О8²Н■О=Н wО1dЧA░$Н■О1РН■О6dН wО*╧ЧA░$Н■О+GН■О/╧Н wОIHНмО┤Ч$6tН[О┤Ч$6tН■О"dН■ОРН wОcЧA░$Н■О)Н■О$²Н wО$ЧA░$Н wОDвН wО@e~НxОOНxОJ╛ЬЗНxОF:П@}ЬЪЗЪН wО:жН wО4+Н wО.Н wО&ж~ЬЗНxОBП+Н╠О5П8НxО6╚ПFНxО0ПFН╠О;╛НxО=VП3ЬЪЗЪНмОUЬЗН╠О.VПVН╠О'╚ПVН╠О!ПNНxО"╚ПVН╟О!▌ НxО)VПErОН ыН#ґН*$Н.÷Н1GдTVm$7COMMONMBUSSPECIFICATIONS20ABCyclePhase0BABABABA123Figure 5. Timing for WriteSingle4requestor: MnRq _ FALSE;arbiter: MnGnt _ FALSE;master: {MnRq _ TRUE; MCmd _ WriteSingle; MAddr _ WSAddress; MnAdCycle _ FALSE}master: {MData _ WSData; MnAdCycle _ TRUE}; arbiter: MnGnt _ TRUE;master: MParity _ WSDataParity; slave: match => MnShared _ FALSE;AB5slave: match => MnShared _ TRUE;FORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНE}ЬЪЗЪН■ОNвН■ОL·НмОQ·Н"ОP┌ЧG$Н"ОSвЧG$Н ИОQ·НИОM╨Н wОLЧCи$Н wОG·ЧCи$Н■ОH,Н■ОJeН wОC,ЧCи$Н■ОC╨Н■ОEСН wО>╨ЧCи$Н■О?HН■ОA│Н wО:HЧCи$Н■О:жН■О=НИОIHНмО3аЧ$ :Н[О3аЧ$ :НИОDвНИО@eН■О$²НИО<│~НxОOНxОJ╛НxОF:ПOЬЗНxОBПBНxО=²ПA}ЬЪЗЪН■О8²Н■О6dН wО5жЧCи$НИО8~ЬЗНxО8ДrОН ыН#ґН*$Н.÷Н1GЪ▌TVm$ЮCOMMONMBUSSPECIFICATIONS21321ABABAB0PhaseCycleBAFigure 6. Timing for IOReadrequestor: MnRq _ FALSE;arbiter: MnGnt _ FALSE;master: {MCmd _ IORead; MAddr _ IOAddress; MnAdCycle _ FALSE; MnRq _ TRUE}master: MnAdCycle _ TRUE; slave: MData _ IOData; arbiter: MnGnt _ TRUE;FORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНE}ЬЪЗЪНИО@eНИОDвН[О<єЧ$VНмО<єЧ$VНИОIHН■ОA│Н■О?HН wО>╨ЧA░$Н■ОEСН■ОC╨Н wОC,ЧA░$Н■ОJeН■ОH,Н wОG·ЧA░$Н wОLЧA░$НИОM╨Н ИОQ·Н"ОSвЧDФ$Н"ОP┌ЧDФ$НмОQ·Н■ОL·Н■ОNвН#О&G~НxОOНxОJ╛НxОF:ПJЬЗНxОAхПGrОН ыН#ґН*$Н.÷Н1G"TVm$ЁCOMMONMBUSSPECIFICATIONS22321ABABAB0PhaseCycleBArequestor: MnRq _ FALSE;arbiter: MnGnt _ FALSE;Figure 7. Timing for IOWritemaster: {MCmd _ IOWriteFlow; MAddr _ IOAddress; MnAdCycle _ FALSE; MnRq _ TRUE}master: {MnAdCycle _ TRUE; MData _ IOData}; arbiter: MnGnt _ TRUE;FORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНE}ЬЪЗЪНИО@eНИОDвН[О<єЧ$VНмО<єЧ$VНИОIHН■ОA│Н■О?HН wО>╨ЧA░$Н■ОEСН■ОC╨Н wОC,ЧA░$Н■ОJeН■ОH,Н wОG·ЧA░$Н wОLЧA░$НИОM╨Н ИОQ·Н"ОSвЧDФ$Н"ОP┌ЧDФ$НмОQ·Н■ОL·Н■ОNв~НxОOНxОJ╛}Н мО+ж~НxОF:ПOЬЗНxОAхПBrОН ыН#ґН*$Н.÷Н1G#TVm$ЄCOMMONMBUSSPECIFICATIONS236+w32BA5+w1ABABABABABAB0PhaseCycleBA(w>=0)w cycles4+warbiter: MnGnt _ FALSE;requestor: MnRq _ FALSE;arbiter: MnGnt _ TRUE;Figure 8. Timing for IOReadFlowmaster: {MCmd _ IOReadFlow; MAddr _ IOAddress; MnAdCycle _ FALSE}master: MnAdCycle _ TRUE;slave: MnAdCycle _ FALSE => MCmd#Done;slave: {MCmd _ Done; MAddr _ mumble; MnAdCycle _ FALSE}slave: {MnADCycle _ TRUE; MData _ IOData}; master: MnRq _ TRUE;FORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНE}ЬЪЗЪНИО.²НИО@eНИОDвН wО,РЧA░$Н■О-─Н■О/╧Н[О*щЧ$)НмО*щЧ$)НИО3НИОIHН■О4+Н■О1РН wО1dЧA░$Н■О8²Н■О6dН wО5жЧA░$Н■О=Н■О:жН wО:HЧA░$Н■ОA│Н■О?HН wО>╨ЧA░$Н■ОEСН■ОC╨Н wОC,ЧA░$Н■ОJeН■ОH,Н wОG·ЧA░$Н wОLЧA░$НИОM╨Н ИОQ·Н"ОSвЧDФ$Н"ОP┌ЧDФ$НмОQ·Н■ОL·Н■ОNв~НмО;╛НмО=V}НИО7│~НxОJ╛НxОOЬЗНxО0}ЬЪЗЪН■Оу~НxОF:ПAЬЗНxОAхНxО=VП&НxО9+П7ЬЪЗЪНxО4rП?rЬЗОН ыН#ґН*$Н.÷Н1GЪюTVm$COMMONMBUSSPECIFICATIONS246+w32BA5+w1ABABABABABAB0PhaseCycleBAw cycles(w>=0)requestor: MnRq _ FALSE;arbiter: MnGnt _ FALSE;4+warbiter: MnGnt _ TRUE;Figure 9. Timing for IOWriteFlowmaster: {MCmd _ IOWriteFlow; MAddr _ IOAddress; MnAdCycle _ FALSE}master: {MnAdCycle _ TRUE; MData _ IOData}slave: MnAdCycle=FALSE => MCmd#Done;slave: {MCmd _ Done; MAddr _ mumble; MnAdCycle _ FALSE}master: {MData _ IOData; MnRq _ TRUE} slave: MnAdCycle _ TRUE;FORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНE}ЬЪЗЪНИО.²НИО@eНИОDвН wО,РЧA░$Н■О-─Н■О/╧Н[О*щЧ$)НмО*щЧ$)НИО3НИОIHН■О4+Н■О1РН wО1dЧA░$Н■О8²Н■О6dН wО5жЧA░$Н■О=Н■О:жН wО:HЧA░$Н■ОA│Н■О?HН wО>╨ЧA░$Н■ОEСН■ОC╨Н wОC,ЧA░$Н■ОJeН■ОH,Н wОG·ЧA░$Н wОLЧA░$НИОM╨Н ИОQ·Н"ОSвЧDФ$Н"ОP┌ЧDФ$НмОQ·Н■ОL·Н■ОNв~НмО=VНмО;╛НxОOНxОJ╛}НИО7│~ЬЗНxО0H}ЬЪЗЪН мО ╧~НxОF:ПBНxОAхП*ЬЗНxО=VП$НxО8ДП7НxО4rП>rОН ыН#ґН*$Н.÷Н1GпTVm$COMMONMBUSSPECIFICATIONS256+w32BA5+w1ABABABABABAB0PhaseCycleBA(w>=0)w cycles4+warbiter: MnGnt _ FALSE;requestor: MnRq _ FALSE;arbiter: MnGnt _ TRUE;master: {MCmd _ IOReadFlow; MAddr _ IOAddress; MnAdCycle _ FALSE}master: MnAdCycle _ TRUE;slave: MnAdCycle _ FALSE => MCmd#Done;slave: {MCmd _ Done; MAddr _ mumble; MnAdCycle _ FALSE}Figure 10. Timing for MapRef and MapRefDirtymaster: {MnRq _TRUE; MnAdCycle _ TRUE}FORINTERNALXEROXUSEONLYqОgН}rН {ОgОgН!WqН%╘ОgОgН'┐rН(kОgОgН)PqН*цОgrОgН+┼vОgНE}ЬЪЗЪНИО.²НИО@eНИОDвН wО,РЧA░$Н■О-─Н■О/╧Н[О*щЧ$)НмО*щЧ$)НИО3НИОIHН■О4+Н■О1РН wО1dЧA░$Н■О8²Н■О6dН wО5жЧA░$Н■О=Н■О:жН wО:HЧA░$Н■ОA│Н■О?HН wО>╨ЧA░$Н■ОEСН■ОC╨Н wОC,ЧA░$Н■ОJeН■ОH,Н wОG·ЧA░$Н wОLЧA░$НИОM╨Н ИОQ·Н"ОSвЧDФ$Н"ОP┌ЧDФ$НмОQ·Н■ОL·Н■ОNв~НмО;╛НмО=V}НИО7│~НxОJ╛НxОOЬЗНxО0ЬЪЗЪНxОF:ПAЬЗНxОAхНxО=VП&НxО9+П7}ЬЪЗЪН■ОуП,~НxО4rП&rЬЗОН ыН#ґН*$Н.÷Н1GЄTVm$Ъ HELVETICA Ъ HELVETICA ЪMATHЧ÷Ъ TIMESROMANЧ÷ Ъ TIMESROMANЧY ЪLOGOЭЄЪ HELVETICAЧ÷ЪMATHЧФЪ HELVETICAЧ÷Ъ HELVETICAЧФЪ HELVETICAЧЪ HELVETICAЩ┘Ъ TIMESROMANЧФЪ TIMESROMANЧ÷Ъ TIMESROMANЧ÷j ўX&║1 г:sB ÷KОW╡c lt√{c│└Ф┬X┼╩▄╧▌░▓■j/≈∙·k╘ЇЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪЪ[]<>commonmbusspecs.tioga"Friday, March 22, 1985 9:18 pm PST