Int 10 Fn 0F  - Frieze V7.41+ - Installation Check                         [V]

   AH = 0Fh
   SI = F123h
   DI = 321Fh

Return: AH = number of character columns
   AL = display mode (see AH=00h)
   BH = active page (see AH=05h)
   SI = DI = F345h if installed

Notes: if mode was set with bit 7 set ("no blanking"), the returned mode will
     also have bit 7 set
   EGA, VGA, and UltraVision return either AL=03h (color) or AL=07h
     (monochrome) in all extended-row text modes

See Also: AH=0Fh"VIDEO",AH=4Bh"FRIEZE"