http://www.epanorama.net/documents/pc/mouse_adapters.html

seems to confirm the mouse has to be designed to be able to use an adapter.

rumbadumba is correct. A PS/2 mouse must specifically state it also works as a serial mouse in order to work in a serial port with it's correct adapter.

As to where to find them? Try your local computer thrift store or eBay. Just search for "serial mouse". I just searched ebay and found many serial mice for the choosing... including original microsoft serial mice which would be easy to find drivers for any old OS.

Alright, thanks, guys. It's even worse than I thought... even the adapter must be specific to it. Wow. 😢

Man, I hate ebay... *sigh*

I might have a spare serial mouse in my big box of old hardware! If you want you can have it for the cost of postage - if you live in or near the UK??

Ah thanks for the kindness! But no, I live all the way across "the pond" in the US haha.

Ah ok... the postage would have cost more than what the mouse is worth 🤣

I bought my current mouse about 9 years ago. It's a basic Logitech 2-button ball mouse, and it came with a serial adapter for attachment to the PS/2 connector. According to the box:

With the combo connector, the mouse just plugs into your available port, whether it's a serial or PS/2 port. There's no software to install.

The Logitech Model is M-CAA42, and the P/N is 811441-0000. I did a web search, and there are apparently still places that sell this particular model including the following:

https://www.pacificgeek.com/product.asp?ID=77103&C=225&S=s

I haven't purchased anything from this place, so caveat emptor. At any rate, you now have at least one specific model number to look for.

This particular model has a small circular piece on the bottom in which the ball rests/floats, and this piece can be removed so the ball can be completely removed and cleaned, and the rotating sensor cylinders can be cleaned as well.

I haven't used the mouse in a serial port, so I can't comment on its performance in that regard.

Good luck on the search!

The serial connector is a 9-pin connector. You didn't mention whether you had a 9 or 25-pin connector.

If you want to use more modern ones, this gadget should give you some flexibility:
http://www.vetra.com/327text.html

Ok, so it's not _very_ cheap - about the same as a decent new mouse.
But if they were selling it locally(at all) to that price, personally I'd buy it...

Ah thanks for the suggestions, guys! Well the adapter gadget thing is a bit too rich heh. For my situation, I would need a power supply with it, too. "The unit is powered from a 5V DC wall mount power supply which is purchased separately. " But that's really interesting they have that kind of stuff.

But the fact that there's that ps/2 / serial mouse out there, that's cool. Thanks for the model. 😀

I do have a 9 pin connector. I didn't think there were 25 pin connectors in existence -- for mice, that is. I thought the 25 pin ones were only for printers or something like that. That's why I didn't specify. Anyhow, that mouse should work nicely if I were to get it.

9-pin and 25-pin serial connectors existed, and you could get adapters to go either way. Parallel connectors were also 25-pin, but had opposite gender from serial to help reduce confusion.

I have been using Logitech Trackball devices since the early nineties.

The one from the 486 era is PS/2 and comes with 9-pin AND 25-pin serial adaptors. Work great. So great actually that I was unaware of this possible PS/2 / Serial compatibility issue until much later.

It is worth looking into their mice.