INT 5B U - SitBack v3.02R - GET DTAsee Disk Transfer Address
	AX = 8485h
	DL = 79h
Return: CX = 5342h if supported
	    ES:BX -> DTAsee Disk Transfer Address set by last INT 21/AH=1Ah
Note:	this function is provided by SBOS.EXE rather than SB.EXE
SeeAlso: INT 21/AH=1Ah