Found it--it's a Prohance Powermouse 70. Looks like it has the standard left/right buttons, plus 15 additional buttons. Normal config is F1-F10, plus esc, ctr

Found it--it's a Prohance Powermouse 70. Looks like it has the standard left/right buttons, plus 15 additional buttons. Normal config is F1-F10, plus esc, ctrl, user, fn, and enter. The driver allowed you to customize it for apps such as AutoCAD. Typical mechanical ball mouse guts, DE-9 serial connector. Actually pretty high quality, as you'd expect for a CAD peripheral back in the day. Couldn't find an images online (I could take one if anyone is really interested), but I did see that someone was trying to reverse engineer the protocol: http://stuartl.longlandclan.yi.org/blog/2006/03/03/reverse-engineering-project-driver-for-the-prohance-powermouse-70/ http://stuartl.longlandclan.yi.org/blog/2006/03/03/reverse-e... chadaustin's mention of a custom mousing surface makes me think he was looking at a digitizer, although it could have been an old school optical mouse, such as the ones Sun used to use.