If anything, isn't it the other way around? The Pentium MMX has more options for slowing it down...

I think the MMX would be better because it's more flexible with setmul. Playing with cache, bus and multiplier can get you like enough to make test drive 3 playable.
On the other hand, it'll probably run fine at 75 fsb making it a pretty decent CPU for demanding 3D dos titles like quake and duke 3d.

Apple][ wrote on 2025-02-16, 19:12:

Am I going to get better compatibility for older DOS games, if I make a system built around a Pentium 75MHz, RAM 2x8MB, S3 Virge, ESS1869?

Unless you want simplicity or don't want to mess with utilities, no.

The Pentium 75 CPU will give you slower performance overall and the stock FSB speed that it has to run is 50 MHz FSB (1.5 x 50 = 75 MHz). Like the other mentioned, the Pentium 233MMX has more options to slow it down thanks to the TR12 registers it has which can be used with SetMul or CPUSPD to deal with speed-sensitive software.

Regarding RAM, reducing the amount helps with stubborn DOS games but for the most past this can be easily solved with XMSDSK, a very flexible RAMDisk.

The only component that could get you better DOS compatibility is the S3 ViRGE video card.

Gmlb256 wrote on 2025-02-16, 19:29:

Unless you want simplicity or don't want to mess with utilities, no. […]
Show full quote

Apple][ wrote on 2025-02-16, 19:12:

Am I going to get better compatibility for older DOS games, if I make a system built around a Pentium 75MHz, RAM 2x8MB, S3 Virge, ESS1869?

Unless you want simplicity or don't want to mess with utilities, no.

The Pentium 75 CPU will give you slower performance overall and the stock FSB speed that it has to run is 50 MHz FSB (1.5 x 50 = 75 MHz). Like the other mentioned, the Pentium 233MMX has more options to slow it down thanks to the TR12 registers it has which can be used with SetMul or CPUSPD to deal with speed-sensitive software.

Regarding RAM, reducing the amount helps with stubborn DOS games but for the most past this can be easily solved with XMSDSK, a very flexible RAMDisk.

The only component that could get you better DOS compatibility is the S3 ViRGE video card.

mm.. in general i found the riva 128 is better than the S3, windows 3.1 drivers are good in riva, best in s3, but besa support in riva is much much better, and some modes like 320x240 in s3 cards run at wrong 70hz and need sdd to fix

in emulators the riva is much better, i tried almost all if not all, emus like rocknes works great in riva and not soo good in s3 for example

quickview pro is better in s3 because hardware scaling in other hand, and some s3 card have some games hardware acceleratted like Tomb raider

Anyways, overall after testing hundred of app and games the riva wins over any s3 i tested

theelf wrote on 2025-02-16, 19:45:

mm.. in general i found the riva 128 is better than the S3, windows 3.1 drivers are good in riva, best in s3, but besa support […]
Show full quote

Gmlb256 wrote on 2025-02-16, 19:29:

Unless you want simplicity or don't want to mess with utilities, no. […]
Show full quote

Apple][ wrote on 2025-02-16, 19:12:

Am I going to get better compatibility for older DOS games, if I make a system built around a Pentium 75MHz, RAM 2x8MB, S3 Virge, ESS1869?

Unless you want simplicity or don't want to mess with utilities, no.

The Pentium 75 CPU will give you slower performance overall and the stock FSB speed that it has to run is 50 MHz FSB (1.5 x 50 = 75 MHz). Like the other mentioned, the Pentium 233MMX has more options to slow it down thanks to the TR12 registers it has which can be used with SetMul or CPUSPD to deal with speed-sensitive software.

Regarding RAM, reducing the amount helps with stubborn DOS games but for the most past this can be easily solved with XMSDSK, a very flexible RAMDisk.

The only component that could get you better DOS compatibility is the S3 ViRGE video card.

mm.. in general i found the riva 128 is better than the S3, windows 3.1 drivers are good in riva, best in s3, but besa support in riva is much much better, and some modes lile 320x240 in s3 cards run at wrong 70hz and need sdd to fix

in emulators the riva is much better, i tried almost all if not all, emus lile rocknes works great in riva and not soo good in s3 for example

quickview pro is better in s3 because hardware scaling

overall after testing hundred of app and games the riva wins over any s3 i tested

That's why I said "could" as S3 cards in early DOS stuff are better supported. I haven't forgotten about the screen refresh rate running at 72 Hz for 320x240 and the workaround that I mentioned you last year.

Don't get me wrong, nVidia cards are still good for DOS and I'm currently using a GeForce2 GTS in the computer mentioned in my signature but largely because of the overclocked AGP bus.

Mmx233 might have more slowdown options.

But I would still go with p75 for pure dos.
It just feels more vintage for the job.

Thanks for the info so far.
I just recently went back to building several various vintage PCs. I'm at the point of starting to play with software now, so I still haven't done comparisons myself and rely on discussions like this.

I've done some reading about my next question but I'll ask it anyway.
Can I just add an S3 video card to make it a dual card setup and then boot either one depending on what I want to run? I'm not talking about dual display, just switching the primary video output.

PlaneVuki wrote on 2025-02-16, 20:26:

...
But I would still go with p75 for pure dos.
It just feels more vintage for the job.

Yeah, this could be a reason for my subject... And as mentioned earlier, "simplicity" is part of it too.
Having a few spare parts laying around didn't help either.

Apple][ wrote on 2025-02-16, 20:32:

Thanks for the info so far. I just recently went back to building several various vintage PCs. I'm at the point of starting to p […]
Show full quote

Thanks for the info so far.
I just recently went back to building several various vintage PCs. I'm at the point of starting to play with software now, so I still haven't done comparisons myself and rely on discussions like this.

I've done some reading about my next question but I'll ask it anyway.
Can I just add an S3 video card to make it a dual card setup and then boot either one depending on what I want to run? I'm not talking about dual display, just switching the primary video output.

I have a DOS machine with dual vga card, a AGP riva 128, and a PCI ATI card flashed to output 15khz. I use UNIFLASH to save cmos and load whatever card i need, very simple

I was thinking about switching the primary AGP or PCI output in the BIOS when I need to, but I'll check the UNIFLASH you mentioned.

PlaneVuki wrote on 2025-02-16, 20:26:

Mmx233 might have more slowdown options.

But I would still go with p75 for pure dos.
It just feels more vintage for the job.

Depends entirely on what pure DOS games you want to play. Quake will be slow on the P233MMX, let alone the P75, and compared to the 386 that 1991-era games ran on, the differences between both will be irrelevant.

Personally I find the P75 with its nerfed 25MHz PCI to be the least attractive Pentium and typically one found running Windows 95 - badly.

Interesting.

Too "slow" isn't going to be a problem. I'm finishing a few other builds - K6-2 500, K6-2+ 500, PIII 600, PIII 800.

I don't remember all old "old" DOS games I want to run again. Some titles I had on mind are Sokoban, Brickwall, Blocks (3d Tetris), Space invaders, Pharaoh's Thumb, Lost Vikings, early Duke Nukem and Commander Keen... and other similar ones.

Don't we all like strange builds? 😀

There was a time, that a P75 with PCI would have been an upgrade to someone with just ISA on <=486. As it is with evolution.

The P75 might have been the first pentium I saw, I don't remember it being the fastest, 90 or 100 mhz. It was shortly after ST Judgement Rites came out, maybe as late as 94. Interesting times seeing a speedy DOS! Not the first multimedia PC I used with sound and CD, that was a little bit earlier with a 386SX. But it's all about the pentiums...

Of course the last of the DOS games, that this would be a bit slow. But no big deal if it suits you.

It's fun, isn't it!
I don't want to mess with anything older AT 386 and 486 (for now). I don't have a budget for it too.
I have blurry flashbacks from the old times.
I remember playing some of these games on my first XT4.77 and then another one - AT8MHz. Next came a strange compact and slim 286. I remember adding some 4x256 memory chips on a daughterboard to have 2MB RAM.
I remember drooling over the first 386 DX40 I tried at my wife's work. Can you believe it! It had a whole 80MB hard drive in it! Unseen!
Going through an Intel 486 DX 80 Intel and then a Cyrix, my last PC in the 90s was K6-2 500.
So, definitely, I'm having fun nowadays!

p75 do 20fps in quake. (320x200x256, default screensize)
That is totally playable for me.
Anything above 13fps is playable for me in retro world.
Of course if that is fair for the given hardware.
For example, I wouldn't feel happy with 25fps on my p200+pci, knowing theres something wrong.

Apple][ wrote on 2025-02-16, 20:53:

I was thinking about switching the primary AGP or PCI output in the BIOS when I need to, but I'll check the UNIFLASH you mentioned.

Wouldn't they just be changing bios settings and "recalling" bios setting with UNIFLASH, or did I misunderstand that completely?

H3nrik V! wrote on 2025-02-19, 08:34:

Apple][ wrote on 2025-02-16, 20:53:

I was thinking about switching the primary AGP or PCI output in the BIOS when I need to, but I'll check the UNIFLASH you mentioned.

Wouldn't they just be changing bios settings and "recalling" bios setting with UNIFLASH, or did I misunderstand that completely?

exactly

Is this UNIFLASH you're talking about:
https://www.rainbow-software.org/uniflash/

As others have mentioned before, the P-MMX is more versatile, as you can modify the registers with setmul or cpuspd and get more precise speeds, including the P75, fast 486, slow 486, 386, 286 and slower. It may also run cooler, but I'm not sure about that. But if you want a real P75... why not?