Základní struktura
TheFigureOnTherightShowStheBasicStructureofrom.RomisAinlyComposedofaddressdecoder, MemoryBank, ReadingLeandSsenseamplifier.Romisamemoryaddressedbyaddress.THEADDRESSDECODEROFTHEROMISOMBINALOFANDGATESGIVENTHEADDRESSOFTHESTORAGEUNITOBEACESEDBYTHTECPU a OOTPUTITSTHESTHESMALLESTEMITEMITEMOFALLADDresSInput (FulldeCoding).Afterthen-bitaddresscodeisdecoded,thereare2nresults,andthedriverselects2nwords,thatis,W=2n.TheMemoryBankISAW*Mtwo-DimensionAlArray (WordBitStructure) uspořádané, coungbyelementssuchasfuses, diody, ortransistory, bez.TheMemoryBankISactuallyacomminationOforgates a theNemumberumformputpLineSthenMermoforgates.AritonlylyadsinformationWhenItworks, v nich.
Pracovní proces
TherightFiguresShowStheworkingProcessofrom.TheCPUsendstheaddressofthememoryunittobeaccessedviatheaddressbus,andtheaddressdecoderselectsawordaccordingtotheinputaddresscodeThen,itdrivesthebitlinesofthewordline,readsthebinarycodestoredineachstoragebitoftheword,sendsittothereadlineoutput,andthensendsittotheCPUviathedataline.
Funkce
TheFeatureOfread-pouzeMeMoryiSthatCanonlyReadBuTNotwriteInformace.Obvykle ABASICICINPUT/OUTSYSTEMSISSOlidifiedIntheroMofthecotherMotherboard, nazvaný BIOS (BasicInputOutputSystem).ITSMAINFUNCTUNCTIONCOMPETTETEPOWER-CHECKOFTHESYSTEM, TheinitializationofeachFunctionModuleinthesystem, theBasicicinput/outputdriverofTheSystemandtheBooToSoToSoTooToSoToSperatingSystemsstem.
Typ
ThereMeremanypesofrom, aneachread-pouzeMemoryHasitSacteristicsandscopeoFapplication.Fromitsmanufacturingprocessandfunctions,ROMhasfivetypes,namelymask-programmedread-onlymemoryMROM(Mask-programmedROM),programmableread-onlymemoryPROM(ProgrammableROM),erasableprogrammableread-onlymemoryMemoryEPROM(ErasableProgrammableROM),electricallyerasableprogrammableread-onlymemoryEEPROM(ElecricallyErasableProgrammableROM)andfasterasableread-writememory(FlashMemory).
MaskProgramming-reading-pouzeMemory
Informace StoreDenthemaskead-pouzeMemory (MasKrom) je „psán“ bythemanufacturerduringThemaskingProcess.InthemanufacturingProcess, thedataisburnintEntheCircuitWithaspecialMask (maska), někdy smazáno „mascrom“.TEManufacturingCofThisMoryoryIsRelatiatiativellow, AndritisOftenasedIncomputers.Boottostart.MostransistorsareSeTeTtheSectionSectionscherowandColumnlines.INTHELASTMASKPROCESSDURINGManufakturing, TheMoStransistorsareControlledCordingTotHecifiedCodingLayoutTodeterMineterMestHintransistorransistorsistorsistorAreconEdTotherowandColumnlines.TheconneckedEndOneSaresetto1 (OR0) a TheunconNeconEcteconesoresetto0 (OR1).OnCethiskIndofMemoryIsManufAftaredBetMemanefActurer, theuserCannotModifyit.
TheMainadvantageOfMromisThattHestorageContentisfixed, theinformationSTillexistsforwerfailure, andthereliabilityIsHigh.TheDisadvantageiSttheInformationCannotBemodifiedOncewteritten (vyrobeno), isveryInflexibleandhasalongProductionCle.
ProgrammableRead-pouzeMemory
ProgramMablerom (ProgramMablerom, Prom) umožňuje SuserstowRiTheinformationtheyNeedatonetiMetHroughAdedDevice (programátor), itisgenerallyprogrambleonce, aeachStorageUnitofTheMoryISall1orall0WhenitleavestHefactory.WHentheuseRuseSit, usetheprogrammingMetHoMethepromStoretherequireddata.
ThereMemanyPesofProm, který RequireElectricityAndTowriteandStoreProgramSandinformace.ButitCanonlybewrententonce, a jejichformationwterittenforthefirsttimeispermanelylylyly angared.Forexample, bipolarpromhastwostructures: OneiTheFuseblownTyp, a TheotheotherthepnJunctionbreakDownTyp.Oni sekanonlyberewritentonce, aonchetheprogrammingiscompleted, jejich contentispermanent.DuetopoorereliabilityAndone-timeprogramming, israrelyused.TheProgramandDatainPromarewittenBitbytheuserusingSpecialequipment, jakmile se kananotbechangedStoredPermanenennennennennennennennennennennenns.Promhasacerveregreelexibility, vhodná forsMallBatchProduction, andisofennudeusedIndustrialControlMachinesoreLectricalAppliancencescences.
ProgramMableRasableProgramMableReadonLyMemory
ProgramovableRasableProgramMableReadonLyMory (EPROM) canbeprogrammedMultipletiMe.ItisakindofthemainwritabLableMableMeMory.ItisakindofromTatisConvenientForUserstowriteAccordingTotheirneeds, a canerasethethewittentententberorererewriting.ThestoredinformationcanbeprogrammeuserBypowerowon, ortheoriginalstoredInformationCanbeesasedaseDusingMetssuchAsUltravioletsLightSourceorpulSecurrent, a soundheNewinformationCanberewithewithAwriteriteriterswithAwriteriter.EPromismoreconvenient, FlexibleandeconomicaltHanMromandProm.BUTEPROMUSESOSSOUBUBE, který jako je.
THEETHODOFERASINGREMOTESTORAGECONTSCANBEASFOLLY: ElectricMethod (nazývánElectricrewriteablerom) orultravioleleRirRadiationMethod (nazývanýlightrewriteablerom).TheopticallyrewritableromCanusehighvoltageToprogramandwritedAta.Kdyserasing, exposetheCircuitlTravioletlight, athedatacanbeclearedandResed.ObvykleAquartztransparentWindowIsReserEdonThepackageshellTofacilitateExposure.
ElektrickyerasableProgrammableRead-pouzeMemory
ElektrickyerasableProgrammableRead-pouzeMemory(EEPROM)isakindofEEPROMthatcanbewrittenatanytimeThereisnoneedtoerasetheoriginalcontentofthememory.TheWriteoperationTakesMuchlongerthanthereadeareaderation.EepromcombinestHeadvantAgesOfNoteasytolosedAtaandFlexibledodification.OnlyordinaryControl, adresa advatabuseSareRequiredformodification.TheoperatingPrincipleofeePromissimilartoem, buttheerasureisdonebyusingahighelectricfield, sotheisnoneedforantransparentwindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindowindow.Eepromismoreexpensivethaneprom, HasalowerowIntegrationLevel, adahighcost.ItisgenerallyusedStosavetheparametersOfTheSystemSettings, TheinformationStoredoredontheiccard, a controllerinthetvorairConditioner.ButbecauseitcanbeModifiedOnline, ItsreliationIsIsNotasgoodaseprom.
Fast-Eraseread-WriteMemory
Fast-Eraseread-WriteMemory (FlashMemory) Isahigh-hustota, bez volatileread/writeEViceInVentByInTelinkhemid-990s.SpisovánímconductorMemoryHasthecharacteristicsOfeePromandram.ITISABRAND-NEWSTORAGESTRUCTURE, běžně známý .flashmemory.ItwasfirstintroducedInThemiddleandlate1980s, athepriceandFunctionOfflashMemoryAreBetweeeproComanDeeProm.Likeeprom, FlashMemoryuseselectricalicleraSableTechnology a TheentireflashMeMoryCanbeesasedInonetoseveralSeconds, které issumchFastertHANEPROM.Nepřijevo, itCaneraseCiredBlockSintheMoryInsteadofTheenTireChip.FlashMeMoryDoesNotProvideByte však na úrovni.Stejně jakoprom, flashmemoryusenlyonetransistorperbit, SoitcanachievetheSameHighDensitaseProm (ve srovnání toeeProm).„FlashMemory“ ChipuseSasingepowerSupply (3vor5v) Tosupplypower.THESECIalVolTageRequiredForErasingand aprogrammingIsgeneratedInsideTeTeTeTeTeThip, SoitcanbeeraseDased aprogramMedonline."Flash" je také atypická netěsnost.Undernormaluse, TheelectronronsstoredInthefloatingGateCanbestored for100yearswithoutloss.
V současné době FlashMemoryHasbeenwidelyusestomakeallkindsofMobileStorage, takový, cosusbflashdrives ameroryCardsUdesedBigitalCameras/camorders.
OnetimeProgrammableReadonLyMemory (OtProm) ThewritingPrinciplieSthesaaseProm, butinordertosavecosts, poprogrammingandwritingitisnolongererased, sonotransparentwindowissetEsset.Rozsah
BecauseromhasthefeatureofNotlosingInformationAfterpowerFailure, itcanbeuseusesabioschipforComputarTartup.EPROM, Eepromandflashrom (Norflashandnandflash), Performanceisthesameasrom, butcanbererewitted, obecně fasterthanwrite, writequiresahighvereltagethanad, (read5vwrite12v) butflashcanbereadeadeReadeadeReadeadeReadeReDreadeReDeadeReadeReDuderethereadeuseused, tasid, asid, asid, asid, asid..InacomputerSystem, RamisgenerallyusesmasMory, andromisgenerallyuseusedAsfirmWareToResomeHardwaredriverdiverriverriverriverriverriverriverriverriverdiverriverdiverriverriverriverdivers.
ProductionPrinciple
RomaddressdecoderisacombinationOfandgates asItSoutsutPiTSTheSMallestitemoFalladdressInput.ThedeCoderCanberePresententAstheandArrayshowninthefigureontherTheright.„Dot“ MarkeDattheInSectionSectionOfTHehorizontalandverticallinesfThEarrayintheFigureIndicatestheconnectionOf “a„ “.TheMemoryCellbodyiSactuallyacomminationOforgates a ofutputnummberOfromistheNumberOforgates.Každý MiniMimumEmofThedeCodermaybetheinputhoftheorgate, alewhetheracerveminimumCanbetheinputhofTheorgatededSestorageInformace, sothememorycellbodycanberegardedasanorArray.Z theaboveanalysis, WecanlooKatthestructureofromfroMotherperSerspective: ItisComposetoftwoarrays- "a" Gatearrayand "nebo" Gatearrayray.TheContentof "nebo" issetbytheuser, soitisprogramble a theandarrayisusedtoformallthesmallestitems, soitisnotprogrammable.