F100 SYSTEMS
I second the above comments on flyability and updating
NDBs were very easy as groundspeed and track were clearly displayed, what else do you want. On an ILS you did not get DME if the wrong runway was entered, not sure how this would be presented on a non ILS runway
There was a problem that the systems were designed for european operation and so if out of dme range for some time perculiar effects could be seen. The system seemed to assume that any errors were due to system drift and allow for it in future but if the percieved drift was due to poor dme quality the system could correct for non existing drift and induce an error