INT 10,12 - Video Subsystem Configuration (EGA/VGA)

	AH = 12h
	BL = 10  return video configuration information
	on return:
	BH = 0 if color mode in effect
	   = 1 if mono mode in effect
	BL = 0 if 64k EGA memory
	   = 1 if 128k EGA memory
	   = 2 if 192k EGA memory
	   = 3 if 256k EGA memory
	CH = feature bits
	CL = switch settings
	BL = 20  select alternate print screen routine
	BL = 30  select scan lines for alphanumeric modes
	   AL = 0  200 scan lines
	      = 1  350 scan lines
	      = 2  400 scan lines
	on return:
	AL = 12
	BL = 31  select default palette loading
	   AL = 0 enable default palette loading
	      = 1 disable default palette loading
	on return:
	AL = 12
	BL = 32  CPU access to video RAM
	   AL = 0  enable CPU access to video RAM and I/O ports
	      = 1  disable CPU access to video RAM and I/O ports
	on return:
	AL = 12
	BL = 33  Gray scale summing
	   AL = 0  enable gray scale summing
	      = 2  disable gray scale summing
	on return:
	AL = 12
	BL = 34  cursor emulation
	   AL = 0  enable cursor emulation
	      = 1  disable cursor emulation
	on return:
	AL = 12
	BL = 35  PS/2 video display switching
	   AL = 0 initial adapter video off
	      = 1 initial planar video on
	      = 2 switch active video off
	      = 3 switch inactive video on
	   ES:DX pointer to 128 byte save area (when AL = 0, 2 or 3)
	on return:
	AL = 12
	BL = 36  video refresh control
	   AL = 0 enable refresh
	      = 1 disable refresh
	on return:
	AL = 12