Have you tried the below? All should work on 9x using software renderer:
Chocolate Heretic\Hexen 2.3.0
Crispy Doom 3.2
Doom Legacy 1.48.8
Rude 2.5.0c
ZDoom32 2.8.5c https://github.com/drfrag666/zdoom32
ZDoom-LE 2.8.1f https://github.com/drfrag666/ZDoom-LE

Think for such an old computer fastdoom may be a good option if/when it adds support for those games.

i think that this machine is a little bit overkill for fast doom, why not use the standard dos versions on dos mode, or in windows they should work too

weldum wrote on 2021-10-03, 17:33:

i think that this machine is a little bit overkill for fast doom, why not use the standard dos versions on dos mode, or in windows they should work too

FastDoom is also faster for that kind of machine than the vanilla executables. You can see the benchmarks that I did with a K6-2+/450 CPU here.

Although the original levels are indeed overkill though unless it brings support for SIGIL but that would increase the RAM requirements.

i don't know, I've been playing sigil on my dos machine (p133, 32mb, 98se) with boom (doom with visplanes an other corrections) under dos and it's flawless, under windows is choppy

There are some parts in SIGIL where you will experience slowdown even in 320x200 on DOS, I witnessed that on a P233MMX prior upgrading.

I should have written that the machine is strictly WIN95B/DX5. I'll try what you mentioned.

Can test compatibility of this port with hexen and heretic:
https://github.com/drfrag666/ZDoom-CL/releases

I believe that uses directdraw version 3.

The PCX1 is probably a dx3-compatible video card.