INT 10 - VIDEO - ALTERNATE FUNCTION SELECT (PS, EGA, VGA, MCGA) - GET EGA INFO

	AH = 12h
	BL = 10h
Return: BH = video state
	    00h color mode in effect (I/O port 3Dxh)
	    01h mono mode in effect (I/O port 3Bxh)
	BL = installed memory (00h = 64K, 01h = 128K, 02h = 192K, 03h = 256K)
	CH = feature connector bits (see #00022)
	CL = switch settings (see #00023,#00024)
	AH destroyed (at least by Tseng ET4000 BIOS v8.00n)
Note:	one possible check for the presence of an EGA or later display card
	  is to call this function with BH=FFh; if not present, BH will be
	  unchanged on return
	another installation check is used by Athena Digital's HGCIBM, which
	  sets CX to FFFFh on calling and checks whether it has been changed
	  on return
Index:	installation check;EGA