基本的BIOS概念课件

TheBasicBIOSConceptsPresentbyJudyMei2003-81TheBasicBIOSConceptsPresentTheBasicBIOSConcepts1.BIOSIntroduction2.SystemMemoryMap3.BIOSComponentsandFeatures4.BIOSServicesandInterrupts5.I/OPortsAddresses6.Power-On-Self-Test(POST)7.Conclusion2TheBasicBIOSConcepts1.BIO1.BIOSIntroduction

1.1WhatisBIOS1.2TypesofBIOS

1.3PartsoftheROMBIOS31.BIOSIntroduction1.1What1.1WhatisBIOS?

BIOSstandsforBasicInput/OutputSystem.ThesystemBIOSisthelowest-levelsoftwareinthecomputer;itactsasaninterfacebetweenthehardware(especiallythechipsetandprocessor)andtheoperatingsystem.TheBIOSprovidesaccesstothesystemhardwareandenablesthecreationofthehigher-leveloperatingsystems(DOS,Windows95,etc.)thatyouusetorunyourapplications.TheBIOSisresponsibleforallowingyoutocontrolyourcomputer'shardwaresettings,forbootingupthemachinewhenyouturnonthepowerorhittheresetbutton,andvariousothersystemfunctions.Layer#Layer0Hardware1SystemBIOS2OperatingSystem3Application41.1WhatisBIOS?BIOSstandsTheBIOSandHardwareIndependence

InordertoallowoperatingsystemsandapplicationstorunonaPC,(almostirrespectiveofitsage),theBIOSprovidesastandardlayerofservicesthattheoperatingsystemcanuseto"talk"tothehardware.Inturn,theoperatingsystemprovidesstandardservicestoapplicationstoperformtheirfunctions.Thismeansthatonelayerhastoknowhowtocommunicatewiththelayerabove(orbelow)only.This"layering"ofservicesallowsapplicationstorunonvirtuallyanyPCregardlessofthetypeofhardware.5TheBIOSandHardwareIndepend1.2TypesofBIOS

TherearethreestandardBIOSpresentinmostsystemsandlocatedprettymuchatthesameplace:SystemBIOS:ThemainsystemBIOSislocatedina64KBblockofmemoryfromF0000htoFFFFFh.

VGAVideoBIOS:ThisistheBIOSthatcontrolsyourvideocard.Itisnormallyinthe32KBblockfromC0000htoC7FFFh

IDEHarddisksandotherperipheralsBIOS:TheBIOSthatcontrolsyourIDEharddisk,ifyouhaveIDEinyoursystem(whichmostdo)islocatedfromC8000htoCBFFFh.61.2TypesofBIOSThereareth1.3PartsoftheROMBIOSThesystemROMelementsinacomputerusuallyare:POST,theROMBIOSitself,andtheBIOSSetuputility.Thefollowinggraphicdepictstheseelements:PostExecutesatPower-onandsystemresetBIOSsetuputilityDiagnosticsandUtilitysoftwareSystemBIOSExecutesonlywhenyoupress<del>when“Hit<del>torunSETUP”todisplayedExecutesonlywhenyoupress<del>when“Hit<del>torunSETUP”todisplayedAlwaysavailableasinterfacebetweenhardwareandsoftware71.3PartsoftheROMBIOSThes2.X86MemoryMap000FFFFFh1024K00000000hDOScoreprogram000F0000h000C0000h000C8000h000B0000h000B8000h000A0000h000XXXX0hROMBIOSruntimeprogram(64K)ReserveforexpansioncardEGA/VGABIOSBlack&whitetextdataColortextdataEGA/VGAcolorgraphdataDOSapplicationarea960K800K768K736K704K640K0KUppermemoryblock(1M)Basememory4GB(4096K)HMA(HighMemoryArea)1088K00110000hFFFFFFFFh….Extendmemory82.X86MemoryMap000FFFFFh1024MemoryMap9MemoryMap910103.BIOSComponentsandFeatures3.1SystemRAM3.2CMOSRAM3.3ROMBIOS113.BIOSComponentsandFeatures3.1DatainSystemRAMDataAreaLocationRemarkInterruptVectorTable000h-3FFhInterruptvectorsavedassegmentsBIOSDatabase400h-4FFhBIOSworkingarea,includingdescriptionofHDD,FDD,Keyboard,videoandotherBIOScharacteristicsandfunctions123.1DatainSystemRAMDataAre3.2CMOSRAM

CMOS(ComplimentaryMetalOxideSemiconductor)RAMisasmallamountofvolatilememoryinaspecialRAMchipthatstorestherealtimeclocksettingsandconfigurationinformationforaPC.Plug-and-PlayBIOSusesadditionalnon-volatilememorytoholdExtendedSystemConfigurationData(ESCD).ThisisusedtostoresystemresourcesettingsofsystemdevicessuchasIRQandI/Oaddresses.DataAreaI/Oport(Read/Write)SizeDescriptionCMOSRAMdata070h&071h64ByteStoretheClock,POSTandsystemconfigurationdata.133.2CMOSRAMCMOS(CompliDatainCMOSRAMI/OaddressRead/WriteDescription0070hWCMOSRAMaddressregister:Bite7=1disableNMI=0ableNMI0071hR/WCMOSRAMdataregisterToreadCMOSRAM,usethefollowingIntelx86assemblerinstructions:OUT70h,RegisterNumberIN AL,71hTowritetoCMOSRAM,usethefollowinginstructions:OUT70h,RegisterNumberOUT71h,New_Value14DatainCMOSRAMI/OaddressReaPARTSofCMOSCMOSRAMisdividedintoseveralparts:LocationLength

Description

00h–0Fh

16bytes

RealTimeClockdata.

10h–2Fh

32bytes

ISAconfigurationdata.

30h–3Fh

16bytes

AMIBIOS-specificconfigurationdata.

40h–7Fh

64bytes

ExtendedCMOSRAM.Availableinmanycomputers.ManychipsetsincorporatethisadditionalCMOSRAMtostoreadvancedconfigurationinformation.

15PARTSofCMOSCMOSRAMisdivid3.3DatainROMBIOS

VersionInformation,LocationofBIOSroutines,BIOScompatibilityinformation,FloppyDiskDriveParameterTable,HardDiskDriveParameterTable,HardDriveDataTransferRates,VideoParameterTable,SystemConfigurationDataTable,DataTransmissionRateInitializationTable,CompatibilityInformationTables.163.3DatainROMBIOSVersionIROMCompatibilityTable(1)

Address

BIOSServiceTable

FE05Bh

POSTentrypoint

FE2C3h

NMIHandlerentrypoint

FE3Feh

INT13hHardDiskDriveServiceentrypoint

FE401h

HardDiskDriveParameterTable

FE6F2hINT19hBootLoadServiceentrypoint

FE6F5h

ConfigurationDataTable

FE729h

DataTransmissionRateGeneratorTable

FE739h

INT14hSerialCommunicationsServiceentrypoint

FE82Eh

INT16hKeyboardServiceentrypoint17ROMCompatibilityTable(1)AddROMCompatibilityTable(2)Address

BIOSServiceTable

FE987h

INT09hKeyboardServiceentrypoint

FEC59h

INT13hFloppyDiskServiceentrypoint

FEF57h

INT0EhFloppyDiskHardwareInterruptServiceRoutineentrypoint

FEFC7h

FloppyDiskControllerParameterTable

FEFD2h

INT17hParallelPrinterServiceentrypoint

FF045h

INT10hVideoServiceFunctions00hthrough0Fhentrypoint

FF065h

INT10hVideoServiceentrypoint

FF0A4hMDAandCGAVideoParameterTable(INT1Dh)FF841h

INT12hMemorySizeServiceentrypoint

FF84DhINT11hEquipmentListServiceentrypoint18ROMCompatibilityTable(2)AddrROMCompatibilityTable(3)Address

BIOSServiceTable

FF859h

INT15hSystemsServicesentrypoint

FFA6Eh

Low-order128charactersofthe320x200and640x200graphicsfontsFFE6Eh

INT1AhTime-of-DayServiceentrypoint

FFEA5h

INT08hSystemTimerInterruptServiceRoutineentrypoint

FFEF3h

InitialInterruptVectoroffsetsloadedbyPOST

FFF53h

IRETInstructionforDummyInterruptHandler

FFF54hINT05hPrintScreenServiceentrypoint

FFFF0hPower-Onentrypoint

FFFF5hROMDate(inASCII).Eightcharactersinxx/xx/xxformat(e.g05/01/99)FFFFEhSystemModelID(alwaysFCh).

19ROMCompatibilityTable(3)Addr4.BIOSservicesandInterrupts4.1BIOSServices4.2TypesofInterrupts4.3Interruptvectors204.BIOSservicesandInterrupts4.1BIOSServicesBIOSservicesusuallyactionslikereadingandwritingfromtheharddisk,processinginformationreceivedfromdevices,etc.SomespecificexamplesofBIOSservicesare:GeometryTranslationforIDE/ATAHardDrivesOver504MBPlug-and-PlayYear2000ComplianceSupportforIDE/ATAHardDrivesOver2GB214.1BIOSServicesBIOSservices4.2TypesofInterruptsInterruptType

Description

Range

Processor

GeneratedorprocessedbytheCPU.

00h–04h

Hardware

Generatedbyhardwaredevices.EightofthesearehardwiredtoeithertheCPUorthemotherboard.IRQ2,8,9,and11–15arereserved.

08h–0Fh70h–77h

Software

HandledbytheBIOS.05h,10hthrough1Ah,and40h,41h,42h,43h,46h,and4Aharereserved.Therestareavailableforre-vectoringtoprogrammer-writtenroutines.

05h–07h10h–1Fh40h–5Fh

DOSOnlyavailablewhenDOSisactive.INT20hthrough3FharereservedforDOS

20h–3Fh

BASIC

Reserved

80h–BFh

UserINT67hisusedforEMS.Allothersavailableforre-vectoringtouser-writtenroutines.

60h–6Fh

224.2TypesofInterruptsInterru4.3InterruptVectorsTheoriginatoroftheinterruptdoesnotneedtoknowthememoryaddressoftherequiredinterrupthandler.Itonlyneedstoknowtheinterruptnumber.Theinterruptnumberpointstotheinterruptvectortable,atableinlowmemorythatcontainsthesegmentedaddressoftheinterrupthandlingsubroutine.EachtimetheBIOSinitializesthecomputer,itcreatesatableofinterruptvectors(pointerstothelocationoftheinterruptserviceroutineentrypointat0:0000h).10hVideodisplayservices13hDisketteandharddiskservices16hKeyboardservices19hReboot11hEquipmentdetermination14hSerialI/Oservices17hPrinterservices1AhRealtimeclockservices12hMemorysizedetermination15hMiscellaneousservices18hBASIC40hFloppyDisk234.3InterruptVectorsTheorigiInterruptRequestLine(IRQ)24InterruptRequestLine(IRQ)24IRQNumbers(1)SystemInterruptIRQNumberTypicalUse08hIRQ0Systemtimer09hIRQ1Keyboard0AhIRQ2CascadeinterruptforIRQ8-150BhIRQ3Secondserialport(COM2)0ChIRQ4Firstserialport(COM1)0DhIRQ5LPT2ParallelPort

0EhIRQ6

Floppydiskdrives

0FhIRQ7

LPT1,ParallelPort

25IRQNumbers(1)SystemIRQNumberIRQNumbers(2).SystemInterruptIRQNumberTypicalUse70h

IRQ8

RealTimeClockInterrupt

71h

IRQ9

VerticalRetraceInterruptfromVideoDisplayAdapter

72h

IRQ10

Reserved

73h

IRQ11

Reserved

74h

IRQ12

ReservedinISA.MousecontrollerinEISA.

75h

IRQ13

Mathcoprocessorinterruptonanyerror

76h

IRQ14

IDEorMFMharddiskdrivecontroller

77h

IRQ15

SecondIDEharddiskdrivecontroller.Sometimesusedforpowermanagement

26IRQNumbers(2).SystemIRQNumb5.I/OPortsAddresses5.1I/OAddressMap5.2I/OPortsAddresses5.3CGA

VideoI/OPorts5.4MonochromeVideoI/OPorts5.5I/OProgrammerAccess275.I/OPortsAddresses5.1I/O5.1I/OAddressMap285.1I/OAddressMap285.2I/OPortsAddressEachportisidentifiedbya16-bitportnumber(from0–65,535,or00000h–0FFFFh).TheI/Oportaddressesfrom0000h–00FFhareusedbycomponentsmountedonthemotherboard.TheI/Oportsaddresses:TheI/Oportaddressesfrom0100h–03FFhareusedbyISAports.TheI/Oportsaddresses:TheI/Oportaddressesabove0400hareusedbyPCIandEISAports.295.2I/OPortsAddressEachport5.3MonochromeVideoI/OPorts

I/OPort

Read/Write

Description

03B4hWCRTCindexregister03B5hWIndex00h HorizontaltotalIndex01h HorizontaldisplayedIndex02h HorizontalsyncpositionIndex03h HorizontalsyncpulsewidthIndex04h VerticaltotalIndex05h VerticaldisplayedIndex06h VerticalsyncpositionIndex07h VerticalsyncpulsewidthIndex08h InterlacemodeIndex09h MaximumscanlinesIndex0Ah CursorstartIndex0Bh CursorendIndex0Ch Startaddress,highbyteIndex0Dh Startaddress,lowbyteIndex0Eh Cursorlocation,highbyteIndex0Fh Cursorlocation,lowbyteIndex10h Lightpen,highbyteIndex11h Lightpen,lowbyte03B8hWModecontrolregister03BAhRCRTstatusregister305.3MonochromeVideoI/OPorts5.4CGA

VideoI/OPorts

I/OPortRead/WriteDescription03D4hWCRTCindexregister

03D5hWIndex00h HorizontaltotalIndex01h HorizontaldisplayedIndex02h HorizontalsyncpositionIndex03h HorizontalsyncpulsewidthIndex04h VerticaltotalIndex05h VerticaldisplayedIndex06h VerticalsyncpositionIndex07h VerticalsyncpulsewidthIndex08h InterleavedmodeIndex09h MaximumscanlinesIndex0Ah CursorstartIndex0Bh CursorendIndex0Ch Startaddress,highbyteIndex0Dh Startaddress,lowbyteIndex0Eh Cursorlocation,highbyteIndex0Fh Cursorlocation,lowbyteIndex10h Lightpen,highbyteIndex11h Lightpen,lowbyte03D8hWModecontrolregister

03D9hWPaletteregister

03DAhRCRTstatusregister

03DBhWClearlightpenlatch

03DChWPresetlightpenlatch

315.4CGAVideoI/OPortsI/OPo5.5I/OProgrammerAccess

AprogrammercanusetheIntelassemblylanguageinstructionsINandOUTtowritetoandreadfromI/Oportaddresses.Forexample:

MOV DX,03CCh ;readvideoregisteraddressIN AL,DX ;readbytefromI/OportOR AL,10h ;setbit4forRAMDACcontrolMOV DX,03C2h ;writeregisteraddressOUT DX,AL ;writevaluetoI/Oport

325.5I/OProgrammerAccessApr6.Power-On-Self-Test(POST)6.1SystemBootOperation6.2POSTPhases6.3POSTFunctions6.4POSTErrorHandling6.5POSTMemoryTest6.6BIOSConfigurationSummaryScreen6.7ROMExtensions6.8POSTCheckpointCodes336.Power-On-Self-Test(POST)6.16.1SystemBootOperation-coldboot(1)Theinternalpowersupplyturnsonandinitializes.Whentheresetbuttonisreleased,theprocessorwillbereadytostartexecuting.TheBIOSperformsthePower-onself.Ifthereareanyfatalerrors,thebootprocessstops.PostbeepcodescanbefoundinthisareaoftheTroubleshooting.TheBIOSlooksforthevideocard.Inparticular,itlooksforthevideocard'sbuiltinBIOSprogramandrunsit.TheBIOSthenlooksforotherdevices'ROMstoseeifanyofthemhaveBIOS.TheBIOSdisplaysitsstartupscreen.TheBIOSdoesmoretestsonthesystem,includingthememorycount-uptestwhichyouseeonthescreen.346.1SystemBootOperation-co6.2SystemBootOperation–ColdBoot(2)TheBIOSperformsa"systeminventory"ofsorts,doingmoreteststodeterminewhatsortofhardwareisinthesystem.IftheBIOSsupportsthePlugandPlaystandard,itwilldetectandconfigurePlugandPlaydevicesatthistimeanddisplayamessageonthescreenforeachoneitfinds.TheBIOSwilldisplayasummaryscreenaboutyoursystem’sconfiguration.TheBIOSbeginsthesearchforadrivetobootfrom.Havingidentifieditstargetbootdrive,theBIOSlooksforbootinformationtostarttheoperatingsystembootprocess.Ifitfindswhatitislookingfor,theBIOSstartstheprocessofbootingtheOperatingSystem(OS),usingtheinformationinthebootsector.Ifnobootdeviceatallcanbefound,thesystemwillnormallydisplayanerrormessageandthenfreezeupthesystem.356.2SystemBootOperation–CoRunProcessBootBlockStartRunsetupPOSTStartRuntimeStartFinishthePOSTGiveControltoRuntimemodulesDecompressPOSTmodulesDecompressPOSTmodulesDecompressSetupmodulesDecompressRuntimemodulesPress<DEL>YesNo36RunProcessBootBlockStartRunStartingPOST

StartingPOSTWhattheBIOSDoes

Turnthecomputeron.

Jumpstotheaddresspointedtobytheprocessorresetvector(FFFF0h).AllPOSTtestsandinitializationsarethenexecuted.Ifsuccessful,POSTcallsINT19hBootstrapLoader.Presstheresetbutton

Jumpstotheaddresspointedtobytheprocessorresetvector(FFFF0h).AllPOSTtestsandinitializationsarethenexecuted.Ifsuccessful,POSTcallsINT19hBootstrapLoader.Press<Ctrl><Alt><Del>.

TheINT09hkeyboardhardwareinterruptservicetransferscontroltoPOST.POSTdoesnottestmemoryabove64KB,butallothertestsandinitializationsareperformed.POSTthencallsINT19hBootstrapLoader

37StartingPOST6.2POSTPhasesBeforeNMIareenabled,theBIOSPOST:StepDescription

1Writesdatainallmotherboardandadaptercardmemorylocationstoestablishthatparityisgood.

2Enablestheonboardand32-bitslotmemoryparitychecksbywritingtoI/Oport61hwithdatabit2settozero.

3EnablestheI/OchannelchecksignalbywritingtoI/OPort61hwithdatabit3settozero.

386.2POSTPhasesBeforeNMIare6.3PostFunction

TheROMBIOSincludesBIOSPower-OnSelfTestdiagnosticandbootingcodethatteststhecomputercomponents,initializescertaindatastructures,andbootsDOS.POSTperformsseveralfunctions:Executesadiagnosticandreliabilitytestofthecomputer,theROMprograms,andRAMInitializesthechipsandthestandardpartsofthecomputerandplacesarecordofthesystemconfigurationinCMOSRAMandinlowsystemmemorySetsuptheinterruptvectortable,DetectsoptionalequipmentBootstheoperatingsystem396.3PostFunctionTheROMPOSTFunctions–Testsequence(1)ProcessorRegisterTest

ROMBIOSChecksumTest

KeyboardControllerTest

CMOSShutdownRegisterTest

SystemTimerTestTheCH-1timererrororCH-2timererror

MemoryRefreshTest

Base64KBTest

CacheMemoryTest

40POSTFunctions–TestsequencePOSTFunctions–Testsequence(2)CMOSRAMBatteryTest

DisplayVerification

EnterProtectedMode

AddressLineTest

ConventionalandExtendedMemoryTest

DMAControllerTest

KeyboardTest

SystemConfigurationVerificationIfthecontentsof0FhatCMOSRAMlocation0Fh(ShutdownByte)is00h,POSTperformsalltestsandinitializations.41POSTFunctions–Testsequence6.4POSTErrorHandling

AprimaryPOSTfunctionistofindanyconditionsthatpreventproperoperation.POSTdiagnosticroutineslookforsystemerrorsandreporttheminthefollowingmanner.If...Then...

Theerroroccursbeforethedisplayisinitialized.Aseriesofbeepssound.Beepcodesindicatethatafatalerrorhasoccurred.TheerroroccursafterthedisplayisinitializedTheerrormessageisdisplayed.DisplayedBIOSmessagesaredescribedinAppendixA.Aprompttopress<F1>alsoappearsonthescreen.426.4POSTErrorHandlingAprim6.5MemoryTestAMIBIOS(C)1997AmericanMegatrendsInc.

XXXXXKBOK

Hit<DEL>ifyouwanttorunSETUP

(C)AmericanMegatrendsInc.XX-XXXX-XXXXXX-XXXXXXXX-XXXXXX-XXXX-X

436.5MemoryTestAMIBIOS(C)1996.6BIOSConfigurationSummaryScreen(AMI)

SystemConfiguration(C)Copyright1985-1991AmericanMegatrendsInc.

MainProcessorNumericCoprocessorFloppyDriveA:FloppyDriveB:DisplayType:ROM-BIOSDate:

:Pentium:Present:1.2MB5¼:1.44MB3½:VGAorEGA:7/15/95

BaseMemorySizeExt.MemorySizePriMasterPriSlaveSerialPort(s)ParallelPort

:640KB:7808KB::None:3F8,3E8:378

446.6BIOSConfigurationSummary6.7ROMExtensionsOffsetContentsDescription055AAhROMextensionheaderidentifier.1Lengthcode.Thelengthin512-byte(½K)units.A64KBROMextensionhasalengthcodeof128.2Instruction.Normally,thisfieldhasaone-byteFARRETURNinstructionorathree-byteJMPinstruction.3VariesTheheadercontainsanumberofotherfields.Last00hUsually00h.456.7ROMExtensionsOffsetConte6.8POSTCheckpointCodesCodeDescriptionD0hTheNMIisdisabled.Powerondelayisstarting.Next,theinitializationcodechecksumwillbeverified.

D1hInitializingtheDMAcontroller,performingthekeyboardcontrollerBATtest,startingmemoryrefresh,andentering4GBflatmodenext.

D3hStartingmemorysizingnext.D4hReturningtorealmode.ExecutinganyOEMpatchesandsettingthestacknext.

D5hPassingcontroltotheuncompressedcodeinshadowRAMatE000:0000h.Theinitializationcodeiscopiedtosegment0andcontrolwillbetransferredtosegment0.

D6hControlisinsegment0.Next,checkingif<Ctrl><Home>waspressedandverifyingthesystemBIOSchecksum.Ifeither<Ctrl><Home>waspressedorthesystemBIOSchecksumisbad,nextwillgotocheckpointcodeE0h.Otherwise,goingtocheckpointcodeD7h.

D7hPassingcontroltotheinterfacemodulenext.

466.8POSTCheckpointCodesCodeDOSCodeMemoryHarddiskPostCodeBIOSIOCodeLoadOSCodeBIOSBootingAddressIOOperationOSControltheCPUBootOSPostProcessBIOSCode7.Conclusion47OSCodeMemoryHarddiskPostCoQ&AThanksforall!48Q&AThanksforall!48TheBasicBIOSConceptsPresentbyJudyMei2003-849TheBasicBIOSConceptsPresentTheBasicBIOSConcepts1.BIOSIntroduction2.SystemMemoryMap3.BIOSComponentsandFeatures4.BIOSServicesandInterrupts5.I/OPortsAddresses6.Power-On-Self-Test(POST)7.Conclusion50TheBasicBIOSConcepts1.BIO1.BIOSIntroduction

1.1WhatisBIOS1.2TypesofBIOS

1.3PartsoftheROMBIOS511.BIOSIntroduction1.1What1.1WhatisBIOS?

BIOSstandsforBasicInput/OutputSystem.ThesystemBIOSisthelowest-levelsoftwareinthecomputer;itactsasaninterfacebetweenthehardware(especiallythechipsetandprocessor)andtheoperatingsystem.TheBIOSprovidesaccesstothesystemhardwareandenablesthecreationofthehigher-leveloperatingsystems(DOS,Windows95,etc.)thatyouusetorunyourapplications.TheBIOSisresponsibleforallowingyoutocontrolyourcomputer'shardwaresettings,forbootingupthemachinewhenyouturnonthepowerorhittheresetbutton,andvariousothersystemfunctions.Layer#Layer0Hardware1SystemBIOS2OperatingSystem3Application521.1WhatisBIOS?BIOSstandsTheBIOSandHardwareIndependence

InordertoallowoperatingsystemsandapplicationstorunonaPC,(almostirrespectiveofitsage),theBIOSprovidesastandardlayerofservicesthattheoperatingsystemcanuseto"talk"tothehardware.Inturn,theoperatingsystemprovidesstandardservicestoapplicationstoperformtheirfunctions.Thismeansthatonelayerhastoknowhowtocommunicatewiththelayerabove(orbelow)only.This"layering"ofservicesallowsapplicationstorunonvirtuallyanyPCregardlessofthetypeofhardware.53TheBIOSandHardwareIndepend1.2TypesofBIOS

TherearethreestandardBIOSpresentinmostsystemsandlocatedprettymuchatthesameplace:SystemBIOS:ThemainsystemBIOSislocatedina64KBblockofmemoryfromF0000htoFFFFFh.

VGAVideoBIOS:ThisistheBIOSthatcontrolsyourvideocard.Itisnormallyinthe32KBblockfromC0000htoC7FFFh

IDEHarddisksandotherperipheralsBIOS:TheBIOSthatcontrolsyourIDEharddisk,ifyouhaveIDEinyoursystem(whichmostdo)islocatedfromC8000htoCBFFFh.541.2TypesofBIOSThereareth1.3PartsoftheROMBIOSThesystemROMelementsinacomputerusuallyare:POST,theROMBIOSitself,andtheBIOSSetuputility.Thefollowinggraphicdepictstheseelements:PostExecutesatPower-onandsystemresetBIOSsetuputilityDiagnosticsandUtilitysoftwareSystemBIOSExecutesonlywhenyoupress<del>when“Hit<del>torunSETUP”todisplayedExecutesonlywhenyoupress<del>when“Hit<del>torunSETUP”todisplayedAlwaysavailableasinterfacebetweenhardwareandsoftware551.3PartsoftheROMBIOSThes2.X86MemoryMap000FFFFFh1024K00000000hDOScoreprogram000F0000h000C0000h000C8000h000B0000h000B8000h000A0000h000XXXX0hROMBIOSruntimeprogram(64K)ReserveforexpansioncardEGA/VGABIOSBlack&whitetextdataColortextdataEGA/VGAcolorgraphdataDOSapplicationarea960K800K768K736K704K640K0KUppermemoryblock(1M)Basememory4GB(4096K)HMA(HighMemoryArea)1088K00110000hFFFFFFFFh….Extendmemory562.X86MemoryMap000FFFFFh1024MemoryMap57MemoryMap958103.BIOSComponentsandFeatures3.1SystemRAM3.2CMOSRAM3.3ROMBIOS593.BIOSComponentsandFeatures3.1DatainSystemRAMDataAreaLocationRemarkInterruptVectorTable000h-3FFhInterruptvectorsavedassegmentsBIOSDatabase400h-4FFhBIOSworkingarea,includingdescriptionofHDD,FDD,Keyboard,videoandotherBIOScharacteristicsandfunctions603.1DatainSystemRAMDataAre3.2CMOSRAM

CMOS(ComplimentaryMetalOxideSemiconductor)RAMisasmallamountofvolatilememoryinaspecialRAMchipthatstorestherealtimeclocksettingsandconfigurationinformationforaPC.Plug-and-PlayBIOSusesadditionalnon-volatilememorytoholdExtendedSystemConfigurationData(ESCD).ThisisusedtostoresystemresourcesettingsofsystemdevicessuchasIRQandI/Oaddresses.DataAreaI/Oport(Read/Write)SizeDescriptionCMOSRAMdata070h&071h64ByteStoretheClock,POSTandsystemconfigurationdata.613.2CMOSRAMCMOS(CompliDatainCMOSRAMI/OaddressRead/WriteDescription0070hWCMOSRAMaddressregister:Bite7=1disableNMI=0ableNMI0071hR/WCMOSRAMdataregisterToreadCMOSRAM,usethefollowingIntelx86assemblerinstructions:OUT70h,RegisterNumberIN AL,71hTowritetoCMOSRAM,usethefollowinginstructions:OUT70h,RegisterNumberOUT71h,New_Value62DatainCMOSRAMI/OaddressReaPARTSofCMOSCMOSRAMisdividedintoseveralparts:LocationLength

Description

00h–0Fh

16bytes

RealTimeClockdata.

10h–2Fh

32bytes

ISAconfigurationdata.

30h–3Fh

16bytes

AMIBIOS-specificconfigurationdata.

40h–7Fh

64bytes

ExtendedCMOSRAM.Availableinmanycomputers.ManychipsetsincorporatethisadditionalCMOSRAMtostoreadvancedconfigurationinformation.

63PARTSofCMOSCMOSRAMisdivid3.3DatainROMBIOS

VersionInformation,LocationofBIOSroutines,BIOScompatibilityinformation,FloppyDiskDriveParameterTable,HardDiskDriveParameterTable,HardDriveDataTransferRates,VideoParameterTable,SystemConfigurationDataTable,DataTransmissionRateInitializationTable,CompatibilityInformationTables.643.3DatainROMBIOSVersionIROMCompatibilityTable(1)

Address

BIOSServiceTable

FE05Bh

POSTentrypoint

FE2C3h

NMIHandlerentrypoint

FE3Feh

INT13hHardDiskDriveServiceentrypoint

FE401h

HardDiskDriveParameterTable

FE6F2hINT19hBootLoadServiceentrypoint

FE6F5h

ConfigurationDataTable

FE729h

DataTransmissionRateGeneratorTable

FE739h

INT14hSerialCommunicationsServiceentrypoint

FE82Eh

INT16hKeyboardServiceentrypoint65ROMCompatibilityTable(1)AddROMCompatibilityTable(2)Address

BIOSServiceTable

FE987h

INT