> still wondering if the poster of the board with a PS/2 DIN has a working PS/2 mouse on this motherboard.

Hello!

Sorry I had no access to Vogons notification mailbox for some time.

This Chaintech SPM board (indeed) ended up in my possession but it was not my project.
The PS/2 mouse connector was soldered on by a talented experimenter but it never worked. He had an idea the PS/2 mouse operation has something to do with the keboard controller chip AND bios. Since the "proper" controller chip does remain unknown and the existing bios is dubious about PS/2 operation the expriment was halted.

Frankly I have never regretted that too much because I have lots of mice with wheel control (almost like any old PS/2 but standard COM!) and these are quite capable of handling Doom or Quake. Like it really was in the 90s.
Some A4 Tech wheel mice even have a nice 'silver' coating reminding of early ATX case style. When they stopped being all office-grey-white...

IIRC the keyboard controller chip on this mb is socketed. If you might have an idea what it should be to drive PS/2 mice I could look for that. BIOS clues could also change something I suppose.

I have another 486 glory idea, also 😀 Your fastest 486 Ultimate test with PC Player using the rare Cyrix 133Mhz does show around 12 fps. But I have seen (with my own eyes) a 12.6 fps score is possible even without Cyrix 133, just with the common AMD-160Mhz.
(overmarked and/or overclocked X5-133 which are many.)

Since I can see Cyrix-133 is more powerful than 160Mhz AMD (judging by other bench scores) I suppose it could breat the 13 fps limit or even reach 14 fps with the EXP8449 board that I used.

14 fps would be the true ultimate PCP bench score.

If it is ready to support Cyrix 133Mhz, that is.

P.S.
Getting a proper Cyrix for myself and checking this is not too cheap these days. Some people are too crazy driving up the vintage prices asking hundreds of dollars for real vintage - and around a hundred for total crap... 😀 This would not be a healthy plan. 😀

I've only ever seen one cyrix 5x86-133 for sale but their was doubt whether the cpu were an amd or cyrix, it was a gainbery branded upgrade cpu, could've had it for $180 plus post but I backed mostly because of cost constraints at the time, I reckon it was the real deal.

A Holtek HT6542B keyboard controller has built-in PS/2 mouse support. You will need to check the wiring to see if the 7406 is wired properly though. You will want to reference Native PS/2 mouse implementation for 386/486 boards using the keyboard controller

You can use modbin to determine if PS/2 mouse is added in the BIOS, and if not, add it.

The Am5x86-160 has the advantage of a 40 MHz graphic bus, whereas the Cx5x86-133 does not.

dirkmirk, I still have only seen Cyrix 5x86-133/4x chips in the Evergreen adapters, never in a Gainbery.