Does it work with the K6 patches? Because there's some similar timer weirdness as seen in the cachechk speed detection.

Dorunkāku wrote on 2025-02-03, 10:52:

MSxyz wrote on 2024-11-20, 18:47:

To add some gossip to the rumour mill, the U5SD supposedly is a CPU fully compatible with the 486DX, but the built in FPU turned out to be defective, so it was deactivated.

That would have been amazing, because the UMC U5S isn't even fully Intel 486SX compatible.
For example: The Intel 486SX can run Windows 98SE, even the Cyrix 486DLC (a 386 replacement!) can run Windows 98SE, but the UMC U5S can not.

Anyone have a more information on this? I have trouble believing it wasn’t fully compatible… I’d assume Win98 is detecting it wrong before assuming there’s a hardware compatibility issue.

Never mind- I found it in wiki- “ Due to an error in the microcode, Microsoft Windows 98 Second Edition identifies some processors as an Intel Pentium MMX which could cause the operating system and software running within it to crash or exhibit undefined behavior.”

Does setup.exe /nm work or does it still have issues after install?

BinaryDemon wrote on 2025-02-03, 16:02:

Does setup.exe /nm work or does it still have issues after install?

I installed Windows 98SE with a Intel 486 DX2 66 and started swapping CPU's after installation. With a Intel/AMD DX, a Intel SX and a Intel SX2 the OS worked fine. With the UMC it crashes with a 'invalid page fault in module SHLWAPI.DLL' after loading the desktop.

It is not a problem that needs fixing. I intend to run that system with 486SX anyway.

Since there's a dozen other causes for that error, I dunno if it should be regarded as specific to the UMC unless it can be reproduced on other systems.