Int 1A Fn B10D  - Intel PCi BIOS V2.0c - Write Configuration Dword         [X]

   AX = B10Dh
   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: 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 entry may be exchanged in future
     implementations

See Also: AX=B18Dh