I know there have been several threads on this in the past - but most now seem inactive. TL;DR version is Ryzen CPUs (Zen, Zen+ and Zen2) have a bug in an old (Pentium Pro days), poorly documented x86 instruction set called VME. Some people say the issue was fixed by a microcode update and resolved in Ryzen 2000 and newer - but I have a 3700x and still cannot get Windows 98 to run properly as it did on my old Xeon workstation. The primary work-around mentioned - disabling 32-bit protected mode storage drivers - doesn't work for me either. The other workaround discussed, downgrading to Workstation 12.x, isn't an option either since I'm running Win10 1909. I've also not been successful in trying to mask the VME instruction set in the CPUID.
Has anyone been successful with getting Windows 95 or 98 to run on Workstation 15.5 on AMD Ryzen CPUs?
Same issues here. I couldn't make it work with Workstation 15 or 12 but with Workstation 10
See this posting for details:
Works for me here - Win98 SE on a machine with Ryzen 2700X (host is openSUSE Leap 15.2 with 5.6-rc5 kernel). But I didn't test it too throroughly (just booted an old VM and tried to run a few programs) so maybe I'm just not using the part which causes the problems.