Int 10 Fn BF03  - Video - Compaq Extensions - Get Environment              [b]

   AX = BF03h
   BX = 0000h

Return: BH = active monitor
       00h = external
       01h = internal
   BL = master mode
       00h = switchable VDU not present
       04h = CGA
       05h = EGA
       07h = MDA
       08h = switchable LCD controller present
   CH = 00h (reserved)
   CL = switchable VDU mode supported
       bit  0   = CGA supported
       bits 1,2 = reserved (1)
       bit  3   = MDA supported
       bits 4-7 = reserved (1)
   DH = internal monitor type (see below)
   DL = external monitor type (see below)

See Also: AH=1Ah,AX=BF00h,AX=BF01h,AX=BF02h

Values for monitor type:
 00h   none
 01h   dual-mode monitor
 02h   5153 RGB monitor
 03h   Compaq Color monitor
 04h   640x400 flat panel
 05h   VGC monochrome
 06h   VGC color
 07h   LCD VGA