Hello Time-Nuts, Greg Dowd, one of the original engineers on the Datum TS2000 (and still with Symmetricom/MicroSemi), really came through! He found a CD with the TS2000 manual, and converted the Word Perfect file to a PDF. With his permission, I have uploaded the file to the KO4BB web site (it should currently be in the recent uploads section). It has now become obvious why I was having difficulty finding the serial commands to set up the unit, because there are none. The front panel menu is the only way to set the unit up. The only thing the serial port is used for is to output an ASCII string of the time once per second (that can be turned on and off). Regards, Skip Withrow