[snip] The mouse is compatible. I have one plugged into my Lisa, but here's the deal with the serial port: It seems that the Lisa mouse setup was a little strange. The port was covered by a plastic "hood," which attached to the back of the case by snapping into two little holes. One hole on each side of the port. This covers the metal "ring" that you're looking for. (I assume the Mac mouse is also looking for it ;) If you've got the mouse plugged in, chances are good you'll yank the hood off when you try to unplug the mouse. Otherwise, you will snap the plastic catches on this hood when/if you try to remove it, AFAIK. You should be able to take a flat screwdriver, and put it in-between the plastic hood and the case, and pry out on the plastic. It should pop right out. This will also make it much easier to plug/unplug the mouse. :) Regards, Chris Christopher Smith, Perl Developer Amdocs - Champaign, IL /usr/bin/perl -e ' print((~"\x95\xc4\xe3"^"Just Another Perl Hacker.")."\x08!\n"); '