INT 10 - VIDEO - ALTERNATE FUNCTION SELECT (PS) - DISPLAY-SWITCH INTERFACE

	AH = 12h
	BL = 35h
	AL = subfunction
	    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 for 128 byte save area (if AL = 00h-03h)
Return: AL = 12h if function supported
Desc:	switch between two video adapters which may otherwise have address
	  conflicts
SeeAlso: AX=BF00h,AX=BF01h,INT 6D"VGA"