I'm attempting to write some datalogging code using the Xmodem protocol. Unfortunately, i've not been too successful in finding good info on the protocol. can anyone point in the right direction? I've put a rather definitive document and two source code implementations at http://www.geocities.com/westfw/comp.htm (gee, it almost looks like an actual web page!) (The source code isn't likely to be too useful. One is macro-20 for tops20, and the other is BASICA for the original ibm pc.) BillW -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads