The problem with the parallel port is not so much that it is easilly damageds, but that damaging it usually takes out the whole motherboard. It may be more useful to provide an add-on parallel port card with your product than to try to protect the PC parallel port... BillW -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads