There are few different incompatible standards of bus mice. Basically the bus mouse is raw mouse signals going to an ISA card where processing of the raw signals is done and then exposed to computer is some way. PS/2 and COM port mice essentially have most of that ISA card inside them.
Making your own is a bit complicated because of these reasons.

Anonymous Coward wrote on 2022-10-05, 15:56:

It seems the serial converters are kind of bandwidth starved, which becomes an issue over 640x480.

what would serial speed have to do with mouse precision (dpi)?

Anonymous Coward wrote on 2022-10-05, 15:56:

The whole point of the bus mouse was that it provided a lot more resolution

afaik the whole point was cost, omitting microcontroller and using 8255 with lots of irqs burning cpu time. Same reason (cost) amiga/atari ST used raw encoder signal mice.

what would serial speed have to do with mouse precision (dpi)?

This one seems self-evident.

afaik the whole point was cost, omitting microcontroller and using 8255 with lots of irqs burning cpu time. Same reason (cost) amiga/atari ST used raw encoder signal mice.

The bus mouse predates PS/2.

Anonymous Coward wrote on 2022-10-07, 00:16:

what would serial speed have to do with mouse precision (dpi)?

This one seems self-evident.

in the same way Trabant was a proof composites had no future in cars

Anonymous Coward wrote on 2022-10-07, 00:16:

The bus mouse predates PS/2.

and serial mice predate bus ones

Maybe this thing can be reversed ?
Bus mouse adapter for PS2 computers... = opposite direction, but.... ?
https://www.flickr.com/photos/andysretrocompu … in/photostream/

Or maybe it actuall works in both directions already ?
(guess not, as both ends of the adapter block has a identical looking bus/in-port connector)

PS: more pictures here (not mine!):
https://www.ebay.com/itm/234556099514
There also exists PS2 adapter cables as well as DB25 serial ones, that will all fit into that rectangular adapter, not only that DB9 serial.

I have that card and adapter. There are different dongles that plug into the white box. I believe there are dongles for PS/2 and Serial. You wouldn't happen to own the manual, would you?
I think it was designed to allow the inport mouse to work in serial and PS/2 ports. I'm not sure if it's bi-directional. I haven't touched mine in quite a few years, and some of my cables are frayed. I'd like to know more about it. I think at one time I tried to plug a Leaguer bus mouse into a PS/2 port using this adapter but it didn't work. As Tiido said, not all bus mice (mouses?) were made to the same standard, so that might explain the reason.

If anyone needed to eyeball a Logitech card to campare, I posted one here... A pic to show the grandchildren, Logitech Bus Mouse and Card Together!&

I looked up that PMIC chip around then and some supplier claimed to be sitting on a few hundred, enough for hobby scale projects I guess, but not for "real" production.

bestemor wrote on 2022-10-07, 20:53:

BusMouse2PS2adapter.JPG

Afaik this is the part Microsoft cheapened out of in their mice - microcontroller interpreting raw encoder signals send by the inport mouse and outputting serial/ps2

Has anyone ever opened the little white box?

Anonymous Coward wrote on 2022-10-08, 00:26:

... You wouldn't happen to own the manual, would you? ...

You can find some manuals here:
https://minuszerodegrees.net/msmouse/Microsoft%20mouse.htm

Ha! Great find!