Int 1A Fn B108  - Pci Bios V2.0c+ - Read Configuration Byte                [X]

   AX = B108h
   BL = device/function number (bits 7-3 device, bits 2-0 function)
   BH = bus number
   DI = register number (0000h-00FFh) (see #0798)

Return: CF clear if successful
       CL = byte read
   CF set on error
   AH = status (00h,87h) (see #0653)
   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 were exchanged between the initial
     drafts of the specification and final implementation

See Also: AX=B109h,AX=B10Ah,AX=B188h,INT 2F/AX=1684h/BX=304Ch