Maybe the 286 boards used IRQ 12 for certain ports (keyboard) or controller cards.

Maybe dunno - I only had an 8bit ATI VGA and a XT-IDE CF interface connected to it so none of these cards could use IRQ12 because both are 8bit
I *think* kbc pin36 is connected to a trace going somewhere - but without the isa->kbc patch wire the mouse was not moving at all.
I need to investigate more.

there seems to be more to keyboard controllers - today I wanted to test the mod on my UNICHIP 367C motherboard , it does not even boot.
The board won't boot with the VIA controller or a SOYO "MB-301" branded kbc , it will boot with either Amikey or HT6542 controllers. I assume some minor incompatibility exists with newer controllers....

As for the 286th board, look state of the IRQ12 before run the TSR.

Probably the reason for the inoperability is that the bios is very old.
IBM PS/2 appeared in 1988-89. Approximately since this moment in bioses there was support for PS/2 mice. Often it was disabled, but the rest of the BIOS, responsible for the keyboard, worked to be compatible with the PS/2 mode.
In the PS/2 mode, meaning of some minor flags in the KBC state register was changed.
There may also be some hardware inconsistencies.

I have not looked at the 286 mobo yet...
About the 367C one, it's one of the latest 386DX mobos AFAIK so I don't think it has an old BIOS... same as the 286 one - it's a 16mhz mobo
Maybe some designs are just not compatible...

On the label 286 bios there is written 1989 or 1986. It's bad to see.

If you want, I will share with you the sources of TSR.
Try to fix it.
But, the comments there are in a terrible state. Part of the comments are in English, part in Russian.

The 286 BIOS has a copyright of 1985/1986 - I can't say I really care about it not working, it's the 367C mobo that I would like to get going, the BIOS sticker is something like 1987 but the board is a 1993 one - I doubt the dates on the stickers actually refer to the bios program date, they are just copyright markings

edit:
I know nothing about programming 😵

Yes, as expected the 367C 386DX40 mobo bios is not from 1987 , here is the version string from bios data: UNICHIP BIOS VER 2.0A 09/27/1993
I also received the eBay VIA VT82C42N controllers, the board won't boot with one so the mod has nothing to do with it. It just doesn't like these new controllers apparently. 😵

edit:
tried an AMIKEY-2 on the 367C , ps2 mouse works most of the time and you get an automated reset after the boot-sequence memory count (counts once, does a reboot, counts again and then it continues to boot as normal)
weird stuff 🤣

Interesting. So there is some difference between the VIA and AMIKEY-2. Does the AMIKEY-2 work just fine without the ps/2 PCB?

Yes it works but like I said it causes the 367C mobo to do a double reset.

I don't know what happened to the FX-3000 mobo that was working with the VIA kbc but now it does not. The mouse-enable tsr says there is no ps/2 mouse to enable. I soldered a brand new controller (new via kbc, new pcb, new components) but it did not help.
At this point I don't know what's going on.

I had a similar problem, which resolved when I put electrical tap on the bottom of my PS/2 module. I thought I put the nail polish and thick enough, but I guess not. So I wonder if something on the PCB is making contact where it shouldn't?

I wish that was the case... just tried masking the mod (but nothing really can come in contact with it) but still no mouse support gets installed from the TSR. I also reflowed the kbc socket but it did not help. Maybe something died when I tried that Amikey2 kbc that did a double-reboot, I have no idea... at least the board works fine otherwise.

edit:
well... I soldered back the ps2 connector to the controller and the TSR works now - maybe I missed it being mentioned but it seems that for me the TSR will only work with a mouse connected to the ps/2 port
I also discovered that using a 5422 VGA makes the TSR not to work and freeze keyboard controls after it complains that a ps/2 mouse is not found

Did you try the VIA/PCB and AMIKEY2/PCB on a different computer to ensure that adapter is working? What about trying a new VIA KBC, a new AMIKEY2 KBC, and a new PCB? I assume you ordered at least 3. I think I went all out and ordered 6 PCB's for $13 or so.

I mentioned this in a previous post: I soldered a brand new controller (new via kbc, new pcb, new components) but it did not help.
But it seems the kbc wasn't the issue at all , since I have edited my last post some times this is what I found so far:

- the tsr does not work if you don't solder a ps/2 port and have a mouse connected
- using a 5422 or 5429 cirus isa vga makes the tsr to complain that there is no mouse and it locks keyboard input after exiting making a reboot necessary

Oh, sorry. I often have family chaos around me while reading and responding on the forum. So you have isolated the issue to a particular motherboard? If you use the same hardware in another 386 computer, does the adapter module work? What about sticking in a Trident 8900C, removing all other hardware, and not loading anything in config.sys and autoexec.bat? On my AMI board, I had to load the TSR in a particular boot order.

Hey no worries, that's just life 😊
I don't have many suitable mobos anymore, just FX-3000, a 367C and the 286 board, only the FX-3000 works with the mod and the VIA controllers.
The 367C sometimes work with AMIKEY-2 , the 286 one only works with the old version TSR but kb/mouse inputs are messed up.

I don't have a trident ISA vga - in fact I don't have many 16bit VGAs anymore, I currently own: a CL5422 , a CL5429 , a WDC90C30 and some crappy AHEAD/REALTEK ones that are only good for XT systems so I don't even bother with them (surprisingly atm I have plenty of 8bit cards from hercules to svga 🤣). I only kept what I thought I would use and did not gave me issues.

I wish I could offer some probable explanation as to why the FX-3000 stopped working with the PS/2 mouse modification. Perhaps a cold solder joint on IRQ 12. I ran into that problem as well.

^ if you look above you'll see that the mod works but NEEDS a mouse connected to the kbc - else the TSR fails. I don't know if this is valid for all mobos but the FX-3000 behaves like that.

I'll look for this the next time I take my 386 out. I didn't specifically check for the TSR output condition for the case where a mouse is not connected and you are loading the TSR. If you aren't connecting a mouse, you won't really need to run the TSR. In every case, I was able to use the keyboard when a mouse wasn't connected to the modded KBC.

Yeah I was just testing things and had 3 modded controllers but without the ps/2 connectors soldered - that's how I discovered this behavior.

edit:
tested the old vgas (Video7 vga, Ahead vga, OTIVGA, Realtek, 8bit ATIVGA and Sergey's 8bit Trident ISAVGA boards) they all work OK along with the TSR , it's only the Cirus ones that causes kbc to freeze on my system