I have used several styles of Serial comm port mice that fit on Comm1 (9-pin connector somewhat triangular) and Comm2 (25-pin connector, someone rectangular). The Comm2 25-pin connector might be the one that you're thinking of.
The nine pin mouse connector is also known as the PC Standard 9-way D-type mouse with RS-232C sensor technology.
These two serial mice predated the PS/2 Min-DIN Mouse (The little round connector).
Right you are Greg. I happen to have all 3 types lying around the house. I've even got an old games controller that has a 9 pin connector :) . ps2 is a games console. PS/2 is a mouse interface. I'll know what you mean here, but maybe not so much out of context.
Don't expect the PS/2 interface to be plug and play. You might get lucky, but your best bet is to have it plugged in before you turn anything on. Same applies to PS/2 Keyboards. Colour coding was introduced in the late 90s. The mouse PS/2 connector became green, whereas the keyboard became purple.
And wouldn't you know it, but now there's a touchscreen system on the way, coming to your town soon, so we'll have to learn everything all over again. Or rather, forget what we think we know.
Unfortunately, you are right about the lack of plug and play with old PS/2 connections.
I was using my computer one day, and my mouse randomly stopped working. I was like WTH?!
Then I realized that it came unplugged. Plugged it back in and it STILL didn't work. I was like OMGWTFBBQ. So I restarted, and then, as they say, the rest, is history.
5-pin DIN (Deutsches Institute fuer Norm) (Made by the German standardized organization)
I called it 5DIN connector. But that was for a KB. (AT/XT)
the mice could use an adapter if I remember correctly.