INT 10H 12H: EGA/VGA Special Functions/Alternate Select

                                                      Compatibility: EGA VGA 
     See: BL=10H EGA/VGA (get EGA info)
          BL=20H EGA/VGA (use alternate print screen)
          BL=30H     VGA (set text-mode scan-lines)
          BL=31H     VGA (enable default palette loading)
          BL=32H     VGA (enable access to video)
          BL=33H     VGA (enable gray-scale summing)
          BL=34H     VGA (enable cursor emulation)
          BL=35H     VGA (PS/2 display switching)
          BL=36H     VGA (screen refresh on/off)

 These functions are put in place by ROM-Scan when an EGA or VGA card is
 installed and are built into the standard ROMS for PS/2 systems.  They are
 not available on CGA or MDA systems.

See Also: Video Font Definition
          INT 10H: Video Services
          EGA/VGA Data Areas