Int 10 Fn 1A00  - Video - Get Display Combination Code (ps,vga/mcga)       [V]

   AX = 1A00h

Return: AL = 1Ah if function was supported
       BL = active display code (see #0037)
       BH = alternate display code (see #0037)

Notes: this function is commonly used to check for the presence of a VGA
   this function is supported on the ATI EGA Wonder with certain
     undocumented configuration switch settings, even though the EGA
     Wonder does not support VGA graphics; to distinguish this case,
     call AX=1C00h with CX nonzero, which the EGA Wonder does not support

See Also: AH=12h/BL=35h,AX=1A01h,AH=1Bh,AH=1Ch,MEM 0040h:008Ah
Index: installation check;VGA

(Table 0037)
Values for display combination code:
 00h   no display
 01h   monochrome adapter w/ monochrome display
 02h   CGA w/ color display
 03h   reserved
 04h   EGA w/ color display
 05h   EGA w/ monochrome display
 06h   PGA w/ color display
 07h   VGA w/ monochrome analog display
 08h   VGA w/ color analog display
 09h   reserved
 0Ah   MCGA w/ digital color display
 0Bh   MCGA w/ monochrome analog display
 0Ch   MCGA w/ color analog display
 FFh   unknown display type