Perusrakenne
ThefigureontherightShowSthePerusrakenneofrom.RomismincomposedOfAddressDecoder, MemoryBank, ReadoutLineanSensEmPrifier.RomisamemoryAddressedByAddress.TheaddressDecoderoftheromisAcombinationOfandgatesgiventHeaddressOftStorageunitTobeacessedybyThecpu ja theOutputTisthesmallestItemofallAddressInput (FullDecoding).Afterthen-bitaddresscodeisdecoded,thereare2nresults,andthedriverselects2nwords,thatis,W=2n.ThememoryBankisaw*mtwo-dimensionalArray (WordBitStructure) järjestetty syytelementit.TheemorybankisActuactAcombinationOforgates ja theumberofromutputlinesisthenumberOforgates.Siitä lähtien.
Työskentelyprosessi
Therightfigureshowsheworkingprocessofrom.ThecpusendstheaddressofthememoryunittobeacesessedViatheaddressbus, jaTheaddressDecoderSelectSawordaccordingToTheinddressCodeten, iTdrivestHeBitLinesOftLine, lukeeBinaryCodestIneachStoneEraTheDeDaTheDateDeDeDateDeDeDaTheDateDeDeDaTheDaTheDaTheDaTheDaTheDaTheDaTheDaTheDaTheDaTheDaTheDaTheDaTheDaTheDatedline.
ominaisuudet
TheFeatureOfRead-IlymemoryisThaTitCanonlyReadButnotWriteInformations.Yleensä.ITSMAINFUNTELIONSOCHEPTETHEPOWER-TECHECKOFTHESYSYSTEM, TheinitializationOfeactfunctionalModuleinthesystem, TheBasicInput/OutputdriverOftHESYSTEMANDTheBootOperatingSystem.
Tyyppi
Kohdetyypesofrom, jaAchRead-IlyMemoryHasitsOwnCharakteristicsandscopefaplication.Fromitsmanufacturingprocessandfunctions,ROMhasfivetypes,namelymask-programmedread-onlymemoryMROM(Mask-programmedROM),programmableread-onlymemoryPROM(ProgrammableROM),erasableprogrammableread-onlymemoryMemoryEPROM(ErasableProgrammableROM),electricallyerasableprogrammableread-onlymemoryEEPROM(ElecricallyErasableProgrammableROM)andfasterasableread-writememory(FlashMemory).
MaskProgrammingRead-IlyMemory
TheinformationstoredInthemaskRead-IlyMemory (maskrom) on "kirjoitettu" bythentaucturerDuringThemaskingProcess.InthemanufacturingProcess, thedataisburnedintheciruitwithpecialmask (maski), joskus söpö "maskrom".Teemanvalmistaminen.Boottostart.MostransistorsaresetTheinterstionsoftherowandColumnlines.IntHelastmaskprocessduringManufacturing, themoStransistororsareControlleDaccordingTothScecitefiedCodingLayoutTodeTenMineMyHeomostransistorSareconnectedTotherowandColumnline -laitteet.TÄYTTÖÖNTEETTÄVÄTONSARESTO1 (OR0) ja THE INCONNECTEDONESARESTO0 (OR1).OncetriseMyismafucturedByThemanvalturang, TheusercannotModifyit.
MromromisthatThestorageContentiSfixed, TheInformationStillexistsAfterPowerFailure ja ThereeliabilightHigh.ThedisadvantageThattheInformationCannotbemodifieDoncewressn (valmistettu), iTisveryInflexibleandhasalongProductionCycle ja theDedePendenceBetweTheuserandththemanucturerislarge.
Ohjelma
Programmablerom (ProgrammaBlerom, Prom) sallii.Whentheuserusesit, usethepRogrammingMethodtomakeThepromstoreTherequiredData.
Kohdetyypit.ButitCanonlyBewrunteonce, ja.Forexample, Bipolarpromhastwostruktuurit: OneSThefuseblownTyyppi ja ThatheristhepnJunctionbreakDownTyyppi.He ovat CanonlyBerewresstunce, AndonceThePrammingisCompleted, heidän kontenttipermmantentti.DuetopoorreliabilityDanne-timeProgramming, ITISREARY-käytetty.ProgramandDatainPromarewressteByTheSerusingsPecialEquipment, kerran kirjoitettu, he ovat.PromhasacuchegreeOffleksibility, sopivatForsmallbatchproduction, andisoftenuseDIninDustrialControlMachinesorelctionAppliances.
Ohjelmoita
ProgrammableERasableProgrammablereaDonlyMemory (EPROM) CANBEPROGRAMMEDMULTIPLETIMES.ITISAKINDOFTHEMAINDRITABLEDREADABLEMEMORY.ITISAKINDOFROMTHATICONVENESSFORSERSTOWRITEACCORDINGTOTHEIRNEEDS, AndcanerasetHewrittencontentBeForerewriting.TheStoreDInformationCanBePRAGRAMMEDBYTEUSERBePOWERINGON, ORTEORIGINALSTOREDIONTIONTIONCANBEEREDESIONINGMETHODSSUCHASULTRAVIOLETLIGHTOURCEORPULSECURRENT.EpromismorEconvent, flexibleandekonomicalthanmromandprom.Butpromusesimpun, joka on ohjeet.
ThemethodoferasingremotestorageContentsCanbeasfollows: ElectricMethod (spectlecricrewriteablerom) orultravioletirradiationMethod (nimeltäänlightrewriteablerom).TeosoptastisestiRitableromcanusehighvoltagetoprogramandwritedata.Jäljempänä, Exposethecircuittoultravioletlight ja theDatacanbecleareDandreused.YleisestioquartztransparentwindowisResernedonthePackageselltofaciliitExPure.
Sähköisesti
SähköpohjainenProgrammableread-yleMemory (EEPROM) ISAKINDOFEEPROMTHATCANBEWRONEANYTIMETHEREISNONEEDTOERASETHEORIGINALCONTENTOFTHEMEMEMORY.TheWriteOperationTakesMuchlongertHanthereadOperation.EepromcombinestheadvantagesOfnoteasytoLosedatadflexiblemodifikaatio.VertaordaryControl, osoite jaDatabusSArerEquiredFormOdfication.TheOperatingPrincipleofepromissimilartoeprom, ButthEerAsureisDoneByusingAHighcricfield, SothereisnoneedForatRansparentWindow.EepromismoreExpenSivethaneprom, HasalowerIntegrationLevel, Andahighercost.ItisgeneralytedToSavetheParameters OfthesTemsettings, TheInformationSTreeNTheICCard ja THEECONTROLLERINTHETTORAIRCONDitionerser -.ButbecausitCanbemodifiedOnLine, sensualiabilityisnotasgoodaseprom.
Nopea
Fast-Eraseread-WrItememory (FlashMemory) Isahigh-tiheys, ei-volatileread/WritedEviceInventedByIntelinthemid-1990-luvut.WritingemiconductorMoryHasTheCharacteristicsOfEromandram.ITISABRAND-Newstoragestructure, Yleisesti tunnettua.ITWASFIRSTINTRODEDINTHEMIDDLEANDLATE1980S, JA THEEPRICANEDFUNTERTOFFLASHMEMORYAREBET WEPROMANDEPROM.KuteneProm, FlashMemoryUSESECTRICALESABleTECHNOLOGY ja ATTHEENTIREFLASHMEMORYCANBEERADINONONOTEVERALSECONDS, WHATSUMUCHFASTERTHANEPROM.ITCANERASECECTIONBLOCKSINTHEMEMORYINSTEADOFOFTHEENTIRECHIP.FlashmemoryDoesnotProvideByte-tasonsure kuitenkin.Kuteneprom, FlashMemoryUSESONLONEtRANSISTORPERBIT, SOITCANACHIEVETHESAMEHighdensityasEprom (verrattuna)."FlashMemory" ChipusSasingLePowersupply (3VOR5V) TOSUPPLYPOWER.THESPECIALVOLTAGEREQUIDEDFORERASINGADANDPROGRAMINGISGENeratedInSidetHechip, SoitCanbeeredAndandProgramedonline."Flash" on myös epätyypillinen haihtumaton muisti.Ala -AllormaLuse, ElectronsStoredInthefloatingGatecanBestoredfor100YearSwithOutloss.
Tällä hetkellä flashmemorybeenWideelydeytedtomaKealKindSofMobilestorage, SuchasusbFlashDrivesandmemoryCardsustedByDigitalCameras/Camcorders.
OneTimeProgrammablereaDonlyMemory (OTPROM) TheWritingPrincipleThesameprom, ButinorderToSaveCosts, Aftervoragningandwrititisnolongerererattu, sonotransparentwindowisset.Laajuus
BacauseromhasthefeatureofnotlosingInformationAfterPowerFailure, ItCanbeUsedasabioschipForcomputStarTup.Eprom, eepromandflashrom (Norflashandnandflash), ThePerformanceThesameasrom, ButcanBerewressted, yleensäReadfasterThanwrite, WriterequiresahightOltAgethanRead, (lue5vwrite12VecandloweDakedledwrite12VecandloweDagedwrite12 -.Tietokoneen tietokone, ramisgeneralytedasmemory, andromisgeneralytedasfirmwaretotoseomehardwaredrivers.
Tuotanto
RomaddressDecoderisAcombinationOfandgates, jaSoutputTisthesmallestItemofallAddressinput.ThedecodercanberepresentedastheandarrayShowninthefigugeontheright."Piste" merkitsevänätHorizontalandverticallines ofTheArrayinthefigureindicatSheconnections "ja".ThemEMoryCellBodyActUncomombinationOForgates ja.Jokainen minimitItemOftheDecodermaybetheinputtofeftoftheorgate.FromTheaboveanalysis, WecanlookTatTructureofromfromanoterPerspektive: itiscompoosedoftwoArrays- "ja" Gatearayand "tai" GatArray.Thecontentof "tai" issetbyTheuser, Soiitisprogrammable ja theandraRayisusedToformallTheSmallestItems.