Selects the number of scan lines for alphanumeric modes. The selected value takes effect the next time Int 10H Function 00H is called to select the display mode.
Call with:
AH = 12H
AL = scan line code
00H = 200 scan lines
01H = 350 scan lines
02H = 400 scan lines
BL = 30H
Returns:
If the VGA is active
AL = 12H
If the VGA is not active
AL = 00H