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There are two configuration methods, depending on the PCI chipsets used:

Configuration Type 1:

CF8h D(R/W):
bit   0-7  Index into the configuration space to read/write at CFCh
    11-15  Card ID (0 - 31)
    16-19  PCI Bus ID (0 - 15)
       31  Set to enable the PCI bus configuration space

CFCh D(R/W):
bit  0-31  The index register identified by the PCI bus/card ID/Index in CF8h
           can be accessed here.


Configuration Type 2:

CF8h (R/W):
bit   7  Set to select the PCI configuration space

CFAh (R/W):
bit 0-?  Bus select ?


Finding the PCI devices:

  PCItype:=0;
  outp($CF8,0);
  outp($CFA,0);
  if (inp($CF8)=0) and (inp($CFA)=0) then PCItype:=2
  else begin
    tmp=inpl($CF8);
    outpl($CF8,$80000000);
    if inpl($CF8)=$80000000 then PCItype:=1;
    outpl($CF8,tmp);
  end;
  case PCItype of
    1:begin   {PCI type 1}
        for i:=0 to 511 do
        begin
          outpl($CF8,$80000000+i*longint(2048));
          tmp:=inpl($CFC);
          if ((tmp and $FFFF)<>$FFFF) and ((tmp shr 16)<>$FFFF) then
            _PCI Device: Vendor: (l and $FFFF)  Device: (l shr 16)_
        end;
      end;
    2:begin   {PCI type 2}
        outp($CF8,$80);
        outp($CFA,0);   {Bus select?}
        for i:=0 to 15 do
        begin
          tmp:=inpl(i*256 +$C000);
          if ((tmp and $FFFF)<>$FFFF) and ((tmp shr 16)<>$FFFF) then
            _PCI Device: Vendor: (l and $FFFF)  Device: (l shr 16)_
        end;
        outp($CF8,0);
      end;
  end;


The PCI BIOS interface requires a 386 or better CPU.


--------X-1AB001-----------------------------
INT 1A - ? PCI ? - INSTALLATION CHECK
        AX = B001h
Return: CF clear if installed
            DX = 4350h ('CP')
            CX = 2049h (' I')
--------X-1AB002-----------------------------
INT 1A - ? PCI ? - FIND PCI DEVICE
        AX = B002h
        CX = device ID
        DX = vendor ID
        SI = device index (0-n)
Return: CF clear if successful
                BH = bus number
                BL = device/function number (bits 7-3 device, bits 2-0 func)
--------X-1AB00A-----------------------------
INT 1A - ? PCI ? - READ CONFIGURATION DWORD
        AX = B00Ah
        BH = bus number
        BL = device/function number (bits 7-3 device, bits 2-0 function)
        DI = register number (0000h-00FFh)
Return: CF clear if successful
          CX = Low 16 bit of the DWORD
          DX = High 16 bit of the DWORD

--------X-1AB101-----------------------------
INT 1A - Intel PCI BIOS v2.0c - INSTALLATION CHECK
        AX = B101h
Return: AH = 00h if installed
            CF clear
            EDX = 20494350h (' ICP')
            EDI = physical address of protected-mode entry point (see #0528)
            AL = PCI hardware characteristics (see #0527)
            BH = PCI interface level major version (BCD)
            BL = PCI interface level minor version (BCD)
            CL = number of last PCI bus in system
        EAX, EBX, ECX, and EDX may be modified
        all other flags (except IF) may be modified
Note:   this function may require up to 1024 byte of stack; it will not enable
        interrupts if they were disabled before making the call

Bitfields for PCI hardware characteristics:
Bit(s)  Description (Table 0527)
0      configuration space access mechanism 1 supported
1      configuration space access mechanism 2 supported
2-3    reserved
4      Special Cycle generation mechanism 1 supported
5      Special Cycle generation mechanism 2 supported
6-7    reserved

(Table 0528)
Call protected-mode entry point with:
        registers as for real/V86-mode INT call
        CS = ring 0 descriptor with access to full address space
Return: as for real/V86-mode call
--------X-1AB102-----------------------------
INT 1A - Intel PCI BIOS v2.0c - FIND PCI DEVICE
        AX = B102h
        CX = device ID
        DX = vendor ID
        SI = device index (0-n)
Return: CF clear if successful
        CF set on error
        AH = status
            00h successful
                BH = bus number
                BL = device/function number (bits 7-3 device, bits 2-0 func)
            83h bad vendor ID
            86h device not found
        EAX, EBX, ECX, and EDX may be modified
        all other flags (except IF) may be modified
Notes:  this function may require up to 1024 byte of stack; it will not enable
        interrupts if they were disabled before making the call device ID FFFFh
        may be reserved as a wildcard in future implementations the meanings of
        BL and BH on return were exchanged between the initial drafts of the
        specification and final implementation all devices sharing a single
        vendor ID and device ID may be enumerated by incrementing SI from 0
        until error 86h is returned
--------X-1AB103-----------------------------
INT 1A - Intel PCI BIOS v2.0c - FIND PCI CLASS CODE
        AX = B103h
        ECX = class code (bits 23-0)
        SI = device index (0-n)
Return: CF clear if successful
        CF set on error
        AH = status
            00h successful
                BH = bus number
                BL = device/function number (bits 7-3 device, bits 2-0 func)
            86h device not found
        EAX, EBX, ECX, and EDX may be modified
        all other flags (except IF) may be modified
Notes:  this function may require up to 1024 byte of stack; it will not enable
        interrupts if they were disabled before making the call the meanings
        of BL and BH on return were exchanged between the initial drafts of
        the specification and final implementation all devices sharing the
        same Class Code may be enumerated by incrementing SI from 0 until
        error 86h is returned
--------X-1AB106-----------------------------
INT 1A - Intel PCI BIOS v2.0c - PCI BUS-SPECIFIC OPERATIONS
        AX = B106h
        BL = bus number
        EDX = Special Cycle data
Return: CF clear if successful
        CF set on error
        AH = status
            00h successful
            81h unsupported function
        EAX, EBX, ECX, and EDX may be modified
        all other flags (except IF) may be modified
Note:   this function may require up to 1024 byte of stack; it will not enable
        interrupts if they were disabled before making the call
--------X-1AB108-----------------------------
INT 1A - Intel PCI BIOS v2.0c - READ CONFIGURATION BYTE
        AX = B108h
        BL = device/function number (bits 7-3 device, bits 2-0 function)
        BH = bus number
        DI = register number (0000h-00FFh)
Return: CF clear if successful
             CL = byte read
        CF set on error
        AH = status
             00h successful
             87h bad register number
        EAX, EBX, ECX, and EDX may be modified
        all other flags (except IF) may be modified
Notes:  this function may require up to 1024 byte of stack; it will not enable
        interrupts if they were disabled before making the call the meanings
        of BL and BH on return were exchanged between the initial drafts of
        the specification and final implementation
--------X-1AB109-----------------------------
INT 1A - Intel PCI BIOS v2.0c - READ CONFIGURATION WORD
        AX = B109h
        BL = device/function number (bits 7-3 device, bits 2-0 function)
        BH = bus number
        DI = register number (0000h-00FFh)
Return: CF clear if successful
            CX = word read
        CF set on error
        AH = status
            00h successful
            87h bad register number
        EAX, EBX, ECX, and EDX may be modified
        all other flags (except IF) may be modified
Notes:  this function may require up to 1024 byte of stack; it will not enable
        interrupts if they were disabled before making the call the meanings
        of BL and BH on return were exchanged between the initial drafts of
        the specification and final implementation
--------X-1AB10A-----------------------------
INT 1A - Intel PCI BIOS v2.0c - READ CONFIGURATION DWORD
        AX = B10Ah
        BH = bus number
        BL = device/function number (bits 7-3 device, bits 2-0 function)
        DI = register number (0000h-00FFh)
Return: CF clear if successful
            ECX = dword read
        CF set on error
        AH = status
            00h successful
            87h bad register number
        EAX, EBX, ECX, and EDX may be modified
        all other flags (except IF) may be modified
Notes: this function may require up to 1024 byte of stack; it will not enable
       interrupts if they were disabled before making the call the meanings of
       BL and BH on return were exchanged between the initial drafts of the
       specification and final implementation
--------X-1AB10B-----------------------------
INT 1A - Intel PCI BIOS v2.0c - WRITE CONFIGURATION BYTE
        AX = B10Bh
        BH = bus number
        BL = device/function number (bits 7-3 device, bits 2-0 function)
        DI = register number (0000h-00FFh)
        CL = byte to write
Return: CF clear if successful
        CF set on error
        AH = status
            00h successful
            87h bad register number
        EAX, EBX, ECX, and EDX may be modified
        all other flags (except IF) may be modified
Notes:  this function may require up to 1024 byte of stack; it will not enable
        interrupts if they were disabled before making the call the meanings
        of BL and BH on return were exchanged between the initial drafts of
        the specification and final implementation
--------X-1AB10C-----------------------------
INT 1A - Intel PCI BIOS v2.0c - WRITE CONFIGURATION WORD
        AX = B10Ch
        BH = bus number
        BL = device/function number (bits 7-3 device, bits 2-0 function)
        DI = register number (multiple of 2 less than 0100h)
        CX = word to write
Return: CF clear if successful
        CF set on error
        AH = status
            00h successful
            87h bad register number
        EAX, EBX, ECX, and EDX may be modified
        all other flags (except IF) may be modified
Notes:  this function may require up to 1024 byte of stack; it will not enable
        interrupts if they were disabled before making the call the meanings
        of BL and BH on return were exchanged between the initial drafts of
        the specification and final implementation
--------X-1AB10D-----------------------------
INT 1A - Intel PCI BIOS v2.0c - WRITE CONFIGURATION DWORD
        AX = B10Dh
        BH = bus number
        BL = device/function number (bits 7-3 device, bits 2-0 function)
        DI = register number (multiple of 4 less than 0100h)
        ECX = dword to write
Return: CF clear if successful
        CF set on error
        AH = status
            00h successful
            87h bad register number
        EAX, EBX, ECX, and EDX may be modified
        all other flags (except IF) may be modified
Notes:  this function may require up to 1024 byte of stack; it will not enable
        interrupts if they were disabled before making the call the meanings
        of BL and BH on return were exchanged between the initial drafts of
        the specification and final implementation
--------X-1AB181-----------------------------
INT 1A - Intel PCI BIOS v2.0c - INSTALLATION CHECK (32-bit)
        AX = B181h
Return: as for AX=B101h
--------X-1AB182-----------------------------
INT 1A - Intel PCI BIOS v2.0c - FIND PCI DEVICE (32-bit)
        AX = B182h
        CX = device ID
        DX = vendor ID
        SI = device index (0-n)
Return: as for AX=B102h
--------X-1AB183-----------------------------
INT 1A - Intel PCI BIOS v2.0c - FIND PCI CLASS CODE (32-bit)
        AX = B183h
        ECX = class code (bits 23-0)
        SI = device index (0-n)
Return: as for AX=B103h
--------X-1AB186-----------------------------
INT 1A - Intel PCI BIOS v2.0c - PCI BUS-SPECIFIC OPERATIONS (32-bit)
        AX = B186h
        BL = bus number
        EDX = Special Cycle data
Return: as for AX=B106h
--------X-1AB188-----------------------------
INT 1A - Intel PCI BIOS v2.0c - READ CONFIGURATION BYTE (32-bit)
        AX = B188h
        BL = bus number
        BH = device/function number (bits 7-3 device, bits 2-0 function)
        DI = register number (0000h-00FFh)
Return: as for AX=B108h
--------X-1AB189-----------------------------
INT 1A - Intel PCI BIOS v2.0c - READ CONFIGURATION WORD (32-bit)
        AX = B189h
        BL = bus number
        BH = device/function number (bits 7-3 device, bits 2-0 function)
        DI = register number (0000h-00FFh)
Return: as for AX=B109h
--------X-1AB18A-----------------------------
INT 1A - Intel PCI BIOS v2.0c - READ CONFIGURATION DWORD (32-bit)
        AX = B18Ah
        BL = bus number
        BH = device/function number (bits 7-3 device, bits 2-0 function)
        DI = register number (0000h-00FFh)
Return: as for AX=B10Ah
--------X-1AB18B-----------------------------
INT 1A - Intel PCI BIOS v2.0c - WRITE CONFIGURATION BYTE (32-bit)
        AX = B18Bh
        BL = bus number
        BH = device/function number (bits 7-3 device, bits 2-0 function)
        DI = register number (0000h-00FFh)
        CL = byte to write
Return: as for AX=B10Bh
--------X-1AB18C-----------------------------
INT 1A - Intel PCI BIOS v2.0c - WRITE CONFIGURATION WORD (32-bit)
        AX = B18Ch
        BL = bus number
        BH = device/function number (bits 7-3 device, bits 2-0 function)
        DI = register number (multiple of 2 less than 0100h)
        CX = word to write
Return: as for AX=B10Ch
--------X-1AB18D-----------------------------
INT 1A - Intel PCI BIOS v2.0c - WRITE CONFIGURATION DWORD (32-bit)
        AX = B18Dh
        BL = bus number
        BH = device/function number (bits 7-3 device, bits 2-0 function)
        DI = register number (multiple of 4 less than 0100h)
        ECX = dword to write
Return: as for AX=B10Dh



The PCI configuration space consists of 256bytes per device, the first 64
bytes are laid out as follows, though an adapter may not implement all fields.

Offset  Size    Description:
  00h   WORD    Vendor ID. FFFFh is reserved.
  02h   WORD    Device ID. FFFFh is reserved.
  04h   WORD    System Bus Command
                Bit 0  I/O Space. If set the device is allowed to respond to
                       I/O requests, if clear the device does not respond.
                    1  Memory Space. If set the device is allowed to respond
                       to Meory requests, if clear the device does not
                       respond.
                    3  Special Cycles. If set the device is allowed to monitor
                       special cycles.
                    5  VGA Palette Snoop. If set special snooping behavior is
                       enabled. The device must not respond to DAC writes.
                       If clear palette accesses are treated normally.
                    6  Parity Error. If set the device responds to parity
                       errors, if clear it ignores them. The device must
                       generate parity even if this bit is clear.
                    7  Wait Cycle Control. If set data/address stepping is
                       enabled, disabled if clear.
                    8  System Error Driver. If set the error driver reports
                       parity errors, if clear the system error driver is
                       disconnected.
                    9  Back-to-Back Cycle. If set the device supports back-to
                        -back cycles.
  06h   WORD    System Bus Status
                Bit 7  (R) Fast back-to-back. If set the device is capable of
                       fast back-to-back cycles, if clear it is not.
                    8  Bus Master. Only implemented by Bus Masters
                 9-10  (R) Device Select Timing. DEVSEL# timing. 0: fast,
                         1: medium, 2: slow
                   11  Device Target-abort. Set whenever the device (as target)
                       issues a Target Abort. Write 1 to reset.
                   12  Received Target-abort. Set whenever the device (as
                       Master) receives a Target Abort. Write 1 to reset.
                   13  Master Abort Status. Set whenever the device issues a
                       Master Abort. Write 1 to reset.
  08h   BYTE    Revision Code.
  09h   BYTE    Programming Interface.
  0Ah   WORD    Class. 300h for VGA devices, 1 for 8514/A devices
  0Ch   BYTE    Cache line size
  0Dh   BYTE    Latency timer.
                Bit 0-2  (R)
                    3-7
  0Eh   BYTE    Header type
                Bit 0-6  Current offset for configuration register ?
                      7  Multifunction Device?
  0Fh   BYTE    Bist?
  10h   DWORD   Base0 - Defines a Memory or I/O region used by the device
                Bit  0  (R) Memory or I/O. Set if the region is in I/O space,
                            clear if it is in Memory space.
                   1-2  (R) Locatable Area. 0: Anywhere in 32bit address space
                             1: Below 1MB, 2: anywhere in 64bit address space
                     3  (R) Pre-fetchable. Set if memory is cacheable, clear
                            if not.
                   4-7  (R) Address space size
                  8-31  Memory Base. Upper 24bit of the base address.
  14h   DWORD   Base1 - Similar to Base0
  18h   DWORD   Base2 - Similar to Base0
  1Ch   DWORD   Base3 - Similar to Base0
  20h   DWORD   Base4 - Similar to Base0
  24h   DWORD   Base5 - Similar to Base0
  28h   DWORD   Reserved
  2Ch   DWORD   Reserved
  30h   DWORD   ROM Base - Defines the location & size of the BIOS ROM
                Bit   0  ROM BIOS Decode. Set to enable BIOS access
                  11-14  (R) ROM BIOS Min Size.
                           0:  32K ROM (bits 15-17 R/W)
                           1:  64K ROM (bits 15 RO, 16-17 R/W)
                           2: 128K ROM (bits 15-16 RO, 17 R/W)
                           3: 256K ROM (bits 15-17 RO)
                  15-31  BIOS Base Address. Upper 14-17 bits of the BIOS
                         location. Depending on the BIOS size in bits 11-14
                         the lowest 1/2/3 bits may be forced to 0.
  34h   DWORD   Reserved
  38h   DWORD   Reserved
  3Ch   BYTE    Interrupt Line
                Used for Interrupt Line info during initialisation
  3Dh   BYTE    Interrupt Pin
                Identifies the interrupt lines used
  3Eh   BYTE    Minimum Grant
                Specifies the longest burst allowed
  3Fh   BYTE    Max Lat
                Indicates how often the device geta access to the PCI bus.


Known Vendor/Device ID combinations:
Vendor:   Device:     Card:
0E11h     3032h      Compaq QVision 1280P
1000h                NCR
1002h     4158h      ATI Mach32 (68800-AX)
           4758h      ATI Mach64 (88800-GX)
1005h     2301h      Avance Logic ALG2301
           2302h      Avance Logic ALG2302
           2364h      Avance Logic ALG2364
100Ch     3202h      Tseng ET4000/W32p revA
           3207h      Tseng ET4000/W32p revD
100Eh     9001h      Weitek Viper/PCI
           9100h      Weitek Viper Pro/SE
1011h                Digital
1013h     00A0h      Cirrus Logic CL-GD5430
           00A8h      Cirrus Logic CL-GD5434
           1200h      Cirrus Logic CL-GD7542 (Nordic)
           1202h      Cirrus Logic CL-GD7543 (Viking)
           1204h      Cirrus Logic CL-GD7541 (Nordic Light)
101Ah                NCR
1023h     9420h      Trident TGUI9420DGi
           9430h      Trident TGUI9430
1025h     1435h      Acer Labs M1435 (huh maybe M3145??)
102Bh     0518h      Matrox ?
           0D10h      Matrox Impression Plus
102Ch     00B8h      Chips&Tech CT64310
           00D8h      Chips&Tech CT65545
105Dh     2309h      Number Nine (#9) Imagine-128
1060h                UMC
1142h     3210h      Alliance Pro Motion 3210
1A08h     0000h      Sierra 15064 ?
5333h     8811h      S3 Trio64
           8880h      S3 86c866
           88B0h      S3 86c928P
           88C0h      S3 86c864
           88C1h      S3 86c864P
           88D0h      S3 86c964
EDD8h     A091h      ARK 1000PV
           A099h      ARK 2000PV