Check the green fuse beside the port.

Seems the problem was my keyboard, I tried another USB model and that works fine.

Odd that my primary keyboard won't work with this motherboard natively nor with a converter.

Could that be a chipset issue, or perhaps the keyboard's internal controller?

Could be BIOS bug, too. I remember having seen BIOS updates where USB issues were addressed. Wouldn't be surprised if that would be the case here, given that USB was in its infancy back then.

Modern keyboard? Iv read musings about USB keyboard support, how supposedly some early bioses supported only the most basic USB keyboard messages, and keyboards trying fancy things (NKRO) will not work without ugly hacks like pretending to be several keyboards etc.

My primary keyboard is a Unicomp Classic 104.

https://www.pckeyboard.com/page/product/UNI044A

I'll see if the motherboard's BIOS can be updated, hopefully that will solve the problem.

That looks like a modern artisan keyboard with custom controller. Maybe its USB 2.0 only, maybe its using some niche controller inside like Teensy with incomplete/hacked keyboard USB stack, maybe its reporting very fast pooling rate, plenty of possibilities.

rasz_pl wrote on 2024-05-01, 15:36:

That looks like a modern artisan keyboard with custom controller. Maybe its USB 2.0 only, maybe its using some niche controller inside like Teensy with incomplete/hacked keyboard USB stack, maybe its reporting very fast pooling rate, plenty of possibilities.

Unicomp holds the rights to manufacture IBM's Buckling Spring model M keyboards. I doubt they'd be using a Teensy.

I don't see any options to change the polling rate in the BIOS, just the rate at which presses of the same key are registered and displayed.

Its entirely different thing. USB devices can report max USB pooling rate. I read somewhere about early bioses with USB support being confused by gamer mice reporting 1000Hz pooling rate.
USB is one of those hundreds of pages standards, the only standard worse than USB is Bluetooth. Implementing Wifi, ip4, or even LTE is like walk in the park compared to bluetooth 😀 For example USB keyboard have two or three ways of reporting key presses in the standard 😀
You can learn some usb basics at https://www.usbmadesimple.co.uk/ums_5.htm