1TheworkprincipleoftheMemory1.ThestructureoftheMemoryTheMemoryisusedtodepositthedata.Itistomakeuseofhighandlowevenelectricitytodepositthedata,andthatistosay,itsdepositingdataisanelectricityevenandhighandlow,notthe1234suchasarithmeticfigure,then,ourriddleundone.Socomputerisnotmysterioustoo.AMemorylookslikesomesmalldrawers,thereareeightsmallblanksinasmalldrawer,everysmallblankisusedtodeposittheelectriccharge,theelectricchargespreadstocomeinorreleasepassingtheelectricwirethatconnectwitheachother,astotheelectricchargehowtoplaceinthesmallblank,weneednotworried.Youcanthinktheelectricwireaswaterpipe.Theelectricchargeintheblankiswater.Thatiseasytocomprehend.Thesmalldrawerinsavingeachoneinthemachineisaplacethatputsthedata,wecallitasaUnit.Wecanstartdepositingthedata.Ifyouwanttoputintoafigure12,thatis00001100,weaslongassaveNo.2andNo.3smallblankinfullelectriccharge,butothersmallelectricchargeintheblanktorelease.Buttheproblemcomesout,Memorycontainalotofunits,thelineistoparallel.Whenyouputtheelectricintoablank,youwillputtheelectricchargeintoallunits,andwhenyoureleasetheelectriccharge,youwillputallelectricchargeineveryunit.SohowmanyunitstheMemoryhave,youcanputthesamepiece,thisofcourseisnotwhatwehope,therefore,weneedmakesomevarietiesontheconstructionslightly.Everyunithasacontrolline,Iwanttoputthedataintowhichunit,thecontrollinethatgiveasignalinthisunit.Thiscontrollineopentheswitch,likethis,electricchargecanthenfluxfree,andtheotherunitcontrollineshavenothesignal,sotheswitchdonotopen,cantsufferfromtheinfluence,likethis,thecontrollinethatonlycontrolthedifferentunit,canwriteintoeachunitthedifferentdata.Thesameas,ifwanttotakethedatainacertainunit,andalsoaslongasopenthehomogeneouscontroltheswitchline.2.TheMemorytranslatesthecodeHowwecometocontroltheeveryunitcontrollingline?Acontrolforreturningremarkably,eachunitdollarlineleadstheoutsideoftheintegratedcircuitnotline?Affaircandontbesosimple,one27512have65536unitsinMemory,haveeachlinethederivationto,thisintegratedcircuitmustmorethan60,000feet?Notline,howdo?2Wantingtheviewpointreducesthelinearquantity.Wehaveakindofmethodtocallthisastotranslatethecode,thesimpleintroductionisonce:Canalinerepresent2kindsofappearances,can2linesrepresent4kindsofappearances,can3linesrepresenthowmanykinds,256kindsofappearancesneedagainhowmanylinesrepresent?8kinds?8lines?Soweneed16linestorepresent65536kindsofappearances.3.TheMemorysenablechipandtheconceptofthebusTothis,translatetheproblemofthecoderesolved,letuscomeagaintopayattentiontoanotherproblem.Sendingintoeightlinesofeachunitistousefromwhereof?Itisfromthecalculationonboardtoconnecttocomeover,generally,theseeightlinesbesidesconnectingtheMemory,stillconnectothermachinepiece,Likethisproblemcomeout,theseeightlinesisnotaMemoryandacomputerappropriatly,ifalwaysacertainunitconnectinghereeighton-line,notwell,forexamplethissavingmachinenumberintheunitisfirst0FFH,anothersavingmachineis00H,sothislineafterallistobeplacedinthehighelectricityeven,stilllowelectricityeven?Whowillbeharmful?Sowewanttoletthemseparate.Thewayiseasycertainly,thelinethatbetheoutsidereceivestheintegratedcircuitleadsthefeetaftercomingin,dontreceivedirectlyeachunitgoto,addingonemoresetofswitchinthecenterline.Usuallywestepasidethepassopens,iffacesreallythisissavingtowriteinthedatainthemachine,orwanttoreadadatafromtheMemory,thenstepasidethepassconnecttheline.Thisswitchfromthreefuseschoice:Readingthecontrolcarry,writesthecontrolcarriestochoosetocarrywiththeslice.Wanttowriteinthedataintoasliceofinside,pickoutfirstthatchip,thensendouttowritealetterthenumber,switchmatchthetop,combiningwillspreadtocomeoverofthedata(electriccharge)writesinaninside.Ifread,pickoutfirstthatsliceof,thensendouttoreadtheletterthenumber,theswitchmatchesthetop,datawassentouttogoto.Readdifferentfromwritingaletterthenumbertostillconnecttotheanothertosavethemachineatthesametime,butbecausetheslicechoosesdifferently,althoughreadorwritealetterthenumber,havenothechipenablesignal,soanotherMemorycantmisunderstandopenthedoor,resultintheclash.Sowouldthedifferenthourpickouttwochips?Aslongasistodesignthesystemcant,donotisourpersontocontrolbutbecontrolledbycomputer,ifreallytheemergenceappearstopickouttwochipscircumstancesatthesametime,thatistherowthatelectriccircuitbreakdown,thisisnot3inourdiscussion.Fromtheintroductionabovewehaveseen,theeightlinesusedtodeliverthedataandarenotspecial-used,butalotofcomponentsarepublic-used.Sowecallitasthedatatotalline,bynameBUSinEnglishintotalline,totalnamelybusway。Whocanwalk.And16addresseslineistobeconnectedtogether,callitastheaddresstotalline.4.Thesemi-conductorMemorysclassificationAccordingtoitsfunction,theMemorycanbedividedintoreadandreadrandomMemorytwomajortype.So-calledacontentsforreading,fromthetypefacecomprehensioniscanonlywithfrominsidereading,cantwritinginto,itsimilarlyinourbook,hairarrivingourreturningafter,ourcanreadinginside,mustnotchangethecontentsonthebookasonespleases.AnEnglishforreadingsavingmachineabbreviationisROM(READONLYMEMORY).Memoryso-calledrandomaccess,canrewriteatanytimenamely,thedatathatalsocanreadtheinside,itissimilarinourblackboard,Icanwriteatanytimethethinggoesup,alsocanwipetorewritewiththeblackboard.SavingtheEnglishabbreviationofthemachineaswiththemachineRAM(READRANDOMMEMORY)thesetwokindsofsavingmachinesEnglishabbreviationmustkeepinmind.Attention:theso-calledreadtopointwithrandomaccessallthetimeofnormalworkcircumstancedescendingandspeech,andalsoisatusingthethispieceofsavingthemachine,nottimetopointtomakethispieceofchip.Otherwise,readthesavingdatainthemachinetohowcomeof?Infact,thistruthisveryeasytocomprehend,thebookgetsholdofourhandistocantchange,canbeitstillwhitepaperinininoriginalmaterialoftime,wasprintedbyprintingpressupcertainly.5.ExplaintheotherafewandfamiliarconceptsbythewayPROM,callitastheprogrammableROM.Thisislikeourexercisebook,buyofthetimeisblank,canwritethethinggoup,canoncewriteup,wipedtodonotdrop,soitcanusetowriteonce,ifwritemistake,submitanexpenseaccount.EPROM,callitasthattheultravioletraywipestheprogrammablethatdividedbyreadsthesavingmachine.Itinsideofaftercontentswritegoup,iffeeldissatisfied,canrewriteafterthrowingawaywithakindofspecialmethod,thisistousestheultravioletrayirradiation,ultravioletrayelephantthewordofworksproperly,canthrowawaytheword,thenrewrite.Certainlythenumberoftimesaremany,andalsoineffectivelight,so4anumberoftimesforcanwipedividedbyisalsoalimitedseveral100times.FLASHROM,callitasthethingthatsavethemachinesoon,itissimilarwiththeEPROM,writingupcanalsowipeofftorewrite,butitwanttheconveniencethesome,donotneedthelightshoneon,aslongasusethescienceofelectricitymethodandthencanwipetodividedby,sotheconvenienceismany,andthelifeistooverylong.(Severaltenthousandarriveseveraldonotwait100,000times)Emphasizeagain,thethingsherewriteareallnotatthenormalworkterm.WhetheritisaPROM,EPROMorFLASHROM,theirwritingallhasspeciallimits.Generally,weuseakindofcalledasprogrammablecontrollertodothiswork.Oncepackedtotheworkposition,youwontrewriteliterally.6.Inaddition,todescribetheSingle-chipmicrocomputer8051sconfiguration8051filmshaveROM(Procedurememory,onlytime)andRam(datamemory,couldwritereadable)categories,whichareseparatememoryaddressspace,andgeneralcomputermemoryallocationmethodisthesame.Usuallyonlyonegeneralcomputeraddressspace,ROMandRamthatcanbearbitrarilyplacedinthecontextofadifferentaddressspace,ROMandRamaddressesinaleaguewithdifferentaddressesinthedistributionspace.CPUvisitstheROM,acorrespondenceaddressonlyMemorymodulecanbeROM,andcanalsobeRam,andasimilarvisitdirective.8051intheMemorystructureisdividedintophysicalprocessesmemoryspacean