Int1Ah AX = B109h(在PCI表面配置空間上，讀取Word) -- BIOS Int1Ah

READ CONFIGURATION WORD

Input:
AX = B109h
BH = bus number
BL = device/function number (bits 7-3 device, bits 2-0 function)
DI = register number (0000h-00FFh, must be multiple of 2) (see PCI Configuration Data Format)
Return: 
 CF clear if successful
   CX = word read
CF set on error
AH = status (00h,87h) (see PCI BIOS v2.0 status codes)
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

BUG:

the Award BIOS 4.51PG (dated 05/24/96) incorrectly returns FFFFh for register 00h if the PCI function number is nonzero