VgaFlagsRec

  The byte at 0040:0089 in the BIOS Data Area is a set of bit flags
  containing information pertaining to the status of the VGA^.

 VgaFlagsRec
 76543210
 rs0rpmga           0040:0089 -- VGA Miscellaneous Flags
 ҽ bit mask
  ɺͼ    >  0: 01H  VGA is active; 0=VGA is disabled/inactive
         >  1: 02H  gray-scale summing is enabled; 0=disabled
        >  2: 04H  using monochrome monitor; 0=color display
       >  3: 08H  default palette loading; 0=keeps same colors
  >  5: 20H  DCC display switching enabled; 0=not enabled
  >7,4: 90H  text mode scan lines (bits 7 and 4 together)
                             bit7  bit4  masked
                               0    0     00H    350-line mode
                               0    1     10H    400-line mode
                               1    0     80H    200-line mode
                               1    1     90H    (reserved)
See Also: EGA/VGA Data Areas
          BIOS Data Area
                                    -*-