video modes greater than 13h on EGA, MCGA and VGA indicate INT 10,0 was called with the high bit of the mode (AL) set to 1, meaning the display does not need cleared
function returns byte value at 40:49; On EGA, MCGA and VGA bit 7 of register AL is determined by bit 7 of BIOS Data Area byte 40:87. This bit is usually set by INT 10,0 with bit 7 of the requested mode (in AL) set to 1