https://minuszerodegrees.net/msmouse/Microsoft%20mouse.htm

Could be that Microsoft Bus Mouse - 1 or Microsoft Bus Mouse - 2.

The "InPort" bus mice are a separate thing, also. They use a round plug and a different protocol.

Edit: Some 286 PCs had a "MOUSE" port on the rear side of the chassis.
It looked physically same as a DE-9 port, except for the description.

I've had many MSmice over the years from back when they first made them - and I don't recognize that one!

Also, a PC serial mouse should have a connector that fits a PC serial -= the std PC port is male(pins), hence a PC mouse should be female.

Which leads to the question - is this actually a PC mouse? I don't immediately recall MS making other mice. but I do know they made some things for other systems.
- So it's possible the serial protocol is not compatible -

If it does turn out to be compatible, then your problem is most likely the adapter - serial ports are DTE (Data Terminal Equipment) or DCE (Date Communication Equipment)
The difference is the ordering of the signals on the DB connector.

Both ends can't be the same - one must be DTE and one must be DCE.

Quite possible, your adapter in changing gender also changes DTE<>DCE.

All the Bus mice I've seen have a different connector (but you can never know what MS does/did).

Should be easy enough with a multimeter to see if it's driving the right signals - but you'd have to come up with another way to power the mouse.
You might be able to figure it out by taking it apart and tracing the signal wires.

Alse, IIRC bus mice ran in 5v while serial drew from the 12v signals lines, and signals wouldn't be in the same pins - fortunately the serial current output is low,so it may not damaged a bus mouse - but again you never know.

DaveDDS wrote on 2025-11-16, 15:44:

All the Bus mice I've seen have a different connector (but you can never know what MS does/did).

Which got me thinking - IIRC some early Macs used a DB9 connector for the mouse - Did MS ever make a Mac mouse?

nezwick wrote on 2025-11-16, 15:23:

Could you post photos of the inside of the mouse ?

Looking for more markings and chip identification.

Please stop using the gender changer for this mouse.
As others have mentioned, if it truly is a serial mouse it would have the proper connector.

edit: Microsoft bus mouse - 9 pin, what interface card and where to get it ? relevant ?
edit2: the pinout in that post is for pc98 mouse, not microsoft bus mouse.
edit3: https://www.minuszerodegrees.net/msmouse/MS%2 … bus%20-%202.png

Here's a pic of the inside. It says "BUS MOUSE" clearly, but when I first opened this I didn't even notice.

Of course I ended up with some kind of odd ball thing that isn't compatible.

Thanks for the replies. It looks like a Bus Mouse ISA card with this specific 9 pin interface is basically unobtanium. I guess I'll try to find the true SERIAL version of this "grey eyes" mouse.

nezwick wrote on 2025-11-16, 15:58:

Here's a pic of the inside. It says "BUS MOUSE" clearly, but when I first opened this I didn't even notice.

Of course I ended up with some kind of odd ball thing that isn't compatible.

Thanks
& indeed. It is a microsoft bus mouse

Out of curiosity, is there a chip on the underside of the mouse pcb ?
funny to already see the option for a middle mouse button.

I just checked and there is NO chip on the underside of the PCB.

So this is something I could buy instead, and should theoretically work with a normal serial port?

It is the same mouse but an actual serial version.

Thanks for everyone's quick responses. I think this answers my question and it was just a dumb mistake on my part. I went ahead and ordered that mouse I posted above, and this should finally allow me to start mousing on my 286!

I'll just get rid of the bus mouse version, though now I'll have to disclose that I connected it to a serial port and may have cooked it!!

I marked the thread as "solved" and maybe it will help someone in the future.

Yes, that mouse looks serial.
The IBM adapter cable from 25 to 9 will work though it looks a bit heavy duty for just a mouse. 😀

Since there's no chip, I guess the only thing that could be cooked are the leds & sensors for the X & Y axis.
Though given the low current of a serial port, I'd think it's all still good.

edit: my googlefu doesn't seem to give me any results on the pinout of the DE9 microsoft bus mouse connector. 🙁

Cool! Much appreciated.

Yeah I agree the bus mouse is extremely unlikely to have been damaged by connection to a serial port