Int 21 Fn FFC4 - Topware Network OS V5.10+ - Get/set Lpt Port On Print S [N] AX = FFC4h BL = subfunction 00h get Return: AL = mapped printer port on print server 01h set CL = network printer port (00h LPT1, 01h LPT2, 02h LPT3) CH = local printer (00h LPT1, 01h LPT2, 02h LPT3)