INT D4 - PC-MOS/386 v3.0+ - ENTER/LEAVE NATIVE 386 EXECUTION MODE               
	AH = 10h
	AL = direction (00h return to V86see Virtual-86 Mode mode, 01h enter native mode)
	CX = length in bytes of Native Context Area ( >=1024 )
	DX = segment of Native Context Area
Return: CF clear if successful
	    running in desired mode at instruction following INT D4 call
	    all segment registers converted to appropriate selectors/segments
	CF set on error
	    AX = error code (see #01680 at INT 21/AH=59h/BX=0000h)
Note:	MS-DOS calls are available in protected mode
SeeAlso: AH=11h,AH=12h,AH=13h,INT 2F/AX=1687h,INT 67/AX=DE0Ch,INT 38