The protocol gets saved in a serial EEPROM. The firmware is apparently in masked rom and cannot be upgraded. Trimble has some ancient utilities that let you change the protocol between GPS (only does GGA and VTG sentences unless you paid for custom firmware), TAIP (which Lady Heather now speaks), and TSIP. The utility that you use depends upon the firmware version. I have been playing with the TSIP protocol (that the Datum uses) and may have found why these receivers are failing. After a while, they start reporting a negative PDOP and stop tracking sats and sending time. The only way to recover the receiver is to run the protocol utility again... doing a hard reset does not fix them. ----------------- > Does the which-protocol get saved away someplace or does it start fresh each power up? Do you know if the protocol is real-close or just similar enough to use the same name?