INT 10 - VIDEO - SAVE/RESTORE VIDEO STATE (PS50+,VGA)

	AH = 1Ch
	AL = function
	    00h return state buffer size
		Return: BX = number of 64-byte blocks needed
	    01h save video state
		ES:BX -> buffer
	    02h restore video state
		ES:BX -> buffer containing previously saved state
	CX = requested states (see #00048)
Return: AL = 1Ch if function supported
Notes:	many BIOSes corrupt the video registers when saving the state, so a
	  program should restore the state immediately after saving it (the
	  saved data is uncorrupted)
	the BIOS data area consists of the 96 bytes from 0040h:0049h-00A8h
	this function is not supported when DOS/V is running
	this function may be a better VGA installation check than the usual
	  INT 10/AX=1A00h, since some late-model EGA cards (such as the ATI
	  EGA Wonder) supported that call
SeeAlso: AX=1A00h,AX=5F90h,AX=5FA0h,MEM 0040h:00A8h