If you're saying that you don't even see serial ports detected at 3F8 and 2F8 either on your BIOS system configuration screen (if it has one) or programs like MSD, you might first check that "M5105 enabled" jumper listed in the PDF, as that seems to be your Super I/O chip. Then, the chip is likely software-configured from your BIOS under integrated peripherals or such, and you could make sure the serial ports are enabled there.

If you are saying that the serial ports are there but the mouse driver just doesn't work, you may have the same pinout issue I suggested in another thread. If the ribbon cables/ports and board didn't come together, you should pull out your multimeter and figure out which pin on the motherboard is Ground and then compare to how the ribbon cable is wired.

I will check in the morning. I appreciate your advice.

That jumper is enabled and closed. I was told to visit this for more information:

https://forum.vcfed.org/index.php?threads/ace … d-quirks.45602/

Just to make sure - are there any Serial/COM options in the BIOS?

with M5105 disabled you couldnt boot from floppy/IDE, so unless you are booting from SCSI M5105 is enabled and somewhat working.
M5105 chip has pins responsible for configuring COM 1/2 ports as seen for example here https://stason.org/TULARC/pc/hard-disk-floppy … ives-M5105.html JP3 JP4 JP5 JP9 JP12 JP13 JP14
Your Acer board doesnt have those jumpers which makes me believe its either hardcoded or controlled by BIOS. GAL/PAL chip right next to M5105 is a good candidate for switching those setup pins.

Bad news - M5105 documentation doesnt exist. The only way to learn which pins control what would be reverse engineering from a known documented IO card. The best I can find would be this A2 rev-b card, 2 layer board, high resolution zoomed in photos:
https://www.recycledgoods.com/acer-m5105-a2-i … ller-card-1991/
https://www.ebay.com/itm/154851043616
JP1 JP2 control LPT. They are connected to R24 R25
JP3 COM1 disable, R26 and then ???
JP4 COM2 disable, R27 going to pin 54

cross referencing with https://stason.org/TULARC/pc/hard-disk-floppy … s-IDE-PLUS.html
https://wiki.preterhuman.net/Acer_IDE_PLUS-V2
COM2 is being disabled with JP4 connecting ground to pin 54 thru 4.7kohm. We have a match!
Pin pin 54 is being read when powering on, if its pulled down COM2 is disabled, if its not pulled down its somehow connected to one of serial output lines.
pin 54 is somewhere near "U45" print below M5105 chip on your board, I dont have better picture to see where its going.
I dont know if you can just read this pin voltage with a multimeter on powered system, usually those kinds of config straps are being sampled at RESET and for that you would need an oscilloscope.

Can you take a zoomed high resolution picture of your motherboard around M5105 chip with good lighting?

In the mean time I would reseat long chip in a socket next to it, and if that doesn help try to power system on while pressing with your finger on M5105 chip - its somewhat plausible few legs lost connection due to bad solder and age.

I did see there were some communication settings but when I open ctemouse and check the serial ports, it reports none of them. I even had some diagnostic tools yield back no serial ports.

With that in mind, I have earlier bought a vlb controller with serial ports. It is a GOLDSTAR PRIME 2C VLB VESA LOCAL BUS 4 IDE DEVICES, 1 FLOPPY 2 SERIAL 1 PARALLE. I was informed that I could buy a controller card which should remedy this issue.

Yes that comtest result is very peculiar, no com ports at all 😮
One way this could happen would be if you somehow used wrong DB9 ribbon dongle (there are two common types) and with a mouse plugged in resulting combination shorts to ground same pins used by pin 54 to disable COM ports in the first place. That would be a hell of a coincidence though 😀 you can quickly rule that out by unplugging all lpt/serial cables from the board and running comtest again.

Would simply installing a controller card with serial ports also help?

Yes, so would using ps2 mouse. But that wouldnt solve the mystery 😀

Plus on top of that, the PS/2 mouse port is blocked by the case on my AT build. As you can see that port is blocked so only the ps/2 keyboard is able to be used.

nothing a drill wouldnt solve :]

AvocadoLongfall wrote on 2023-09-30, 16:02:

Plus on top of that, the PS/2 mouse port is blocked by the case on my AT build. As you can see that port is blocked so only the ps/2 keyboard is able to be used.

Try removing the board and everything else from the case and run it outside on an (non-conductive) surface. You might need an extra AT style power supply. Or also remove the power supply.

Usually that makes trouble shooting easier. Everything is better reachable.

What is J11?