INT 17 - Alloy NTNX, MW386 - GET/SET PRINTER MODE
        AH = 99h
        AL = mode
            00h NTNX compatibility
                DL = NTNX printer number (see AH=88h)
                        (FFh = task's current logical LPT1)
                DH = mode
                    bit 0: get mode if 1, set mode if 0
                        1: private ("attached")
                        2: direct instead of spooled
                        3-7 reserved (0)
            01h MW386
                DX = MW386 printer number
                CL = mode (as for DH above)
Return: AL = status (see AH=81h)
        DH = mode (bits 1 and 2 set as above)
        DL = printer owner's user number if not spooled