Format of ANSI.SYS parameter block:
Offset	Size	Description	)
 00h	BYTE	subfunction
		00h set/reset interlock
		01h get /L flag
 01h	BYTE	interlock state
		00h=reset, 01h=set
		  This interlock prevents some of the ANSI.SYS post-processing
		  in its hook onto INT 10, AH=00h mode set
 02h	BYTE	(returned)
		00h if /L not in effect
		01h if /L in effect