INT 10 - VIDEO - ALTERNATE FUNCTION SELECT (PS) - DISPLAY-SWITCH INTERFACE
AH = 12h
BL = 35h
AL = 00h initial adapter video off
01h initial planar video on
02h switch active video off
03h switch inactive video on
80h *UNDOCUMENTED* set system board video active flag
ES:DX -> buffer (128 byte save area if AL = 0, 2 or 3)
Return: AL = 12h if function supported


1012 - VIDEO - ALTERNATE FUNCTION SELECT (PS) - DISPLAY-SWITCH INTERFACE