test old pentium 1 pc with other keyboard .
if error persist
problem with motherboard
else
problem with first keyboard
.

ps. in the bios change the halt on all errors option.

THX Somehow after a while, I can use it normal, can also pass the boot and go manually into BIOS, but strange that the error still appears. I tested it on the other PC with PS2 and there where no errors, but there are also no errors if its not plugged in. THe halt on all errors option is unfortunately not in my bios

Try with typematic rates setting on and off, and look for a KBC clock setting and set that lowest option also.

unfortunately, this is all not avaliable in bios, seems to be a very simple one

Ah is it maybe an OEM model? Thus "It works with the keyboard we shipped it with" ... meaning you might be in for swapping keyboards around until you find one it likes.

It is an IBM PC, so you are maybe right, i need to have a IBM keyboard Could be the case since mainboard looks like a non retail version. but how would a Ps2 port detect a "special" keyboard?

One thing i found out, it shows the error only on power up, while resetting it with keyboard the error is not present anymore until, next power up.

What keyboard and what IBM PC exactly?

Old IBM keyboards (Model F, Model M) were notoriously power-hungry, drawing many times as much as say a simple Cherry board. That meant that some systems (and KVM switches, and USB adapters) specifically have trouble with them if they can't supply all that power over PS/2.

There's also the difference in protocol between XT and AT keyboards, despite the same connector. Some keyboards (non-IBM) had a switch to choose between them. In the wrong setting it won't work. Doesn't sound too likely here though.

dionb wrote on 2022-01-19, 00:49:

What keyboard and what IBM PC exactly?

Old IBM keyboards (Model F, Model M) were notoriously power-hungry, drawing many times as much as say a simple Cherry board. That meant that some systems (and KVM switches, and USB adapters) specifically have trouble with them if they can't supply all that power over PS/2.

There's also the difference in protocol between XT and AT keyboards, despite the same connector. Some keyboards (non-IBM) had a switch to choose between them. In the wrong setting it won't work. Doesn't sound too likely here though.

Could also be the keyboard has a small IC that has identifier information on it the keyboard bios is trying to read at post, seems something IBM would have done back in the day to prevent people using any non IBM keyboard with the PC.

Possibly (although not something I've seen) - all the more reason to have exact PC and keyboard model numbers.

The pc is an ibm aptiva 2151 30a. I did not have any ps2 keyboards so i bought one feom ebay, a fujitsu Siemens, KBPC SX D, S26381-K397-V120

atom1kk wrote on 2022-01-19, 12:44:

The pc is an ibm aptiva 2151 30a. I did not have any ps2 keyboards so i bought one feom ebay, a fujitsu Siemens, KBPC SX D, S26381-K397-V120

Aptiva

Ah well there's ya problem, im guessing it'll have some proprietary shit going on and its looking for and expecting an IBM Aptiva keyboard.

You might find one on eBay that will work.

Might be good if you can borrow another PS/2 keyboard to test with the computer. I think that the keyboard controller has separate pins for input and output on to the clock and data lines. If either the clock or data output connections to the connector have failed then the computer won't be able to signal to the keyboard to reset itself. So the keyboard will never send the acknowledge back that would be expected and would look like it wasn't connected. But the keyboard powers up in a sensible default state, so if the inputs to the keyboard controller are ok then the keyboard would still work. There is a PS/2 identify device command, but I think keyboards all have the same response.

If you get in the BIOS, do numlock/capslock/syslock turn their LEDs on and off correctly? I think their status is controlled by the keyboard controller.

When i turn it on all leds turn on and off. Caps lock turns on and off correctly

When power is first applied the keyboard will do it's own self test, including turning the lights on and off. Caps lock LED might be controlled by the keyboard (I thought it was the controller). Do num lock and syslock work as well?

[edit: just thought, is there a CMOS battery in this machine and does it need changing? Flat or nearly flat batteries can apparently cause some odd effects.]

but how would a Ps2 port detect a "special" keyboard?

It's a bidirectional data port so both ends are capable of sending arbitrary non-standard commands.

All leds work fine. Yes it has a cmos battery, i changed it when i started the pc. Also did a reset via the jumper

Update.

Managed to get another one and works fine, seemed to be a problem with the fujitsu

atom1kk wrote on 2022-01-19, 12:44:

The pc is an ibm aptiva 2151 30a. I did not have any ps2 keyboards so i bought one feom ebay, a fujitsu Siemens, KBPC SX D, S26381-K397-V120

Hey by any chance do you have the drivers for this PC and Motherboard? I cant tell what motherboard is inside.

Sorry for the late reply. Unfortunately not anymore.