There are some AT cases that have a hole for the PS2 mice. The vast majority I've seen, however, do not.

Btw, please do check the pinout of your mouse header. Those were non-standard and your header's pinout might not match the motherboard. You can also try testing that system outside of the case, in a testbench-like setup, and see if the built-in mouse port works.

AFAIK, only late models of AT cases had the proper hole in the back, but these kind of port disposition never became a 'standard'. Here is an example of my retro machine (case dated 1998):

The major part of cases do not look like this one in its back, as they have only a hole for the keyboard port like yours

You can either cut a hole or try to move the board into a ATX, I got two socket 4 boards that have this issue as they have ps/2 ports.

The following makeshift testbench setup allowed me to use the internal PS/2 mouse port. I've confirmed that port works just fine, as indicated by Windows 98 finding new hardware and the fact that the mouse cursor isn't stuck in the center of the screen. Either I'll have to get the multimeter out to see if I need to rearrange the pins on the external connector, or I'll have to see if there's a rotary saw in the house.

According to your motherboard manual, the pinout for PSM2 is:

• 1: Vcc, 2: N/C, 3: GND, 4: Clk, 5: Data

The PS/2 socket is:

• 1: Data, 2: N/C, 3: GND, 4: Vcc, 5: Clk, 6: N/C

So you'll need to confirm (or rewire) your adapter such that:

• Pin 1 -> PS/2 pin 4
• Pin 2 -> N/A (or PS/2 pin 2 or 6)
• Pin 3 -> PS/2 pin 3
• Pin 4 -> PS/2 pin 5
• Pin 5 -> PS/2 pin 1

Well, I'll get to the multimeter continuity tests tomorrow. Opening and closing computers can get a bit exhausting for me, kyuhuk.

Since I wasn't able to find a thin enough metal object to stick through the pin holes on the external PS/2 mouse port, I couldn't perform a multimeter continuity test. As such, I will use a serial mouse for now. When I'm ready (preferably some time after I receive the ODIN RTC battery), I'll find a rotary saw to make way for the onboard PS/2 mouse connector.

You could probably just remove all the contacts with a thin screwdriver and rewire it from scratch....
If you can see which wire goes to which contact on the PS2 connector you can also infer the pinout.

Orkay wrote:

Since I wasn't able to find a thin enough metal object to stick through the pin holes on the external PS/2 mouse port

Use a sewing needle or pin.

Or just plug in a keyboard or mouse, open it up, and probe it that way. Or, probe the bottom of the board.

Azarien wrote:

Use a sewing needle or pin.

You're right... I don't want to saw away a chunk of a good tower just yet! I don't know where I'd find one, so I'll have to ask my mother soon. 🤣

I got the sewing needle, did the continuity tests, and rewired the pins appropriately, but I still couldn't get the external mouse connector to work. I'm quite certain I fried it some time earlier while trying to get it to work with the HOT-433 long ago. Due to the lack of available replacements on eBay, I may as well have to cut out a chunk of the chassis to unblock the internal port.

AFAIK unless there are broken traces in the board, there is no way you coudl've burnt anything. Those pins should be directly shorted to the PS/2 port soldered on the motherboard. You could also run a continuity test between both PS/2 jacks (with the second one connected to the pins) to see if they match.

Definitely - if you did manage to fry it, the continuity test would fail as the fried wire wouldn't be continuous. Are you 101% sure you are looking at the right pinout for the socket? The pins will be numbered incorrectly if you're looking at a diagram of the male connector as opposed to the female socket, and they'll of course be backwards if you're looking at a rear-facing wiring diagram as opposed to the front facing pinout.

Maybe you could get a second sewing needle and see if you get continuity between each pin on the onboard PS/2 socket and the matching pin on the plugged in one. Then it'll be even easier to check that it has been wired correctly.

Here's what I'd do, really.

Remove the board from the case, flip it upside down.

Find the PS/2 port and the PS/2 header's pins.

Put your multimeter in continuity mode, touch one probe to one of the pins of the PS/2 port that you know works (you can get to these without sticking anything in the port, because you're looking at the bottom of the board - you're not sticking the meter in the port, you're sticking it to where the port connects to the motherboard). Touch the other probe to each of the pins of the PS/2 header. Now you know which pin(s) on the header matches that pin on the PS/2 port. Write it down.

Continue for each of the PS/2 port's pins.

You may only have four or five pins connected, and a couple of pins may be shorted together, that's OK. Ultimately, you need Vcc, GND, DATA, and CLK, there'll be two no-connects at the PS/2 port, and there may also be a shield pin (which would be a 7th and possibly 8th pin for where the PS/2 port meets the motherboard, but may not be reflected on the header at all) that's probably shorted to GND.

bhtooefr wrote:

Here's what I'd do, really. […]
Show full quote

Here's what I'd do, really.

Remove the board from the case, flip it upside down.

Find the PS/2 port and the PS/2 header's pins.

Put your multimeter in continuity mode, touch one probe to one of the pins of the PS/2 port that you know works (you can get to these without sticking anything in the port, because you're looking at the bottom of the board - you're not sticking the meter in the port, you're sticking it to where the port connects to the motherboard). Touch the other probe to each of the pins of the PS/2 header. Now you know which pin(s) on the header matches that pin on the PS/2 port. Write it down.

Continue for each of the PS/2 port's pins.

You may only have four or five pins connected, and a couple of pins may be shorted together, that's OK. Ultimately, you need Vcc, GND, DATA, and CLK, there'll be two no-connects at the PS/2 port, and there may also be a shield pin (which would be a 7th and possibly 8th pin for where the PS/2 port meets the motherboard, but may not be reflected on the header at all) that's probably shorted to GND.

Thanks everyone, for keeping me from trying to find a saw to cut a hole in my precious case.

Meanwhile, I received a replacement ODIN chip for this motherboard since the old one had a CMOS checksum error, but I got the same error with the new one. I've ordered a couple of compatible Dallas chips in this matter, figuring the battery was dead on arrival. I ended up breaking a pin when pulling it out, so I figured I wouldn't be able to RMA. Could there be some other cause for the CMOS being unable to store its memory? I'm worried it could possibly be something irreparable, though much of my panic comes from the bad luck I've had with a couple of RTC batteries for a Toshiba Satellite Pro 400CS.

It turns out the solution was painfully simple. Possibly due to the confusing documentation against the motherboard's labels, I had the connector backwards. By reversing the connector with the correct pinout, my external PS/2 mouse port works just as expected! Now I don't have to worry about ruining my case!