INT 10 - VIDEO - ALTERNATE FUNCTION SELECT (PS, EGA, VGA, MCGA) - GET EGA INFO
        AH = 12h
        BL = 10h
Return: BH = 00h color mode in effect (I/O port 3Dxh)
             01h mono mode in effect (I/O port 3Bxh)
        BL = 00h  64k bytes memory installed
             01h 128k bytes memory installed
             02h 192k bytes memory installed
             03h 256k bytes memory installed
        CH = feature bits
        CL = switch settings
Note:   one possible check for the presence of an EGA or later display card
          is to call this function with BH=FFh; if not present, BH will be
          unchanged on return