Int 1A Fn B18B  - Intel PCi BIOS V2.0c - Write Configuration Byte (32-bit  [X]

   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

See Also: AX=B10Bh