Joseph_Joestar wrote on 2025-03-08, 12:29:

However, with L1 cache disabled via SetMul, it seems that the scrolling issue no longer occurs.

I think the whole “DOS compatibility” table from Gona should be taken with a grain of salt. It also doesn’t favor ATi because of some obscure edge-cases while they often do a good job at internal upscaling.

Joseph_Joestar wrote on 2025-03-08, 12:29:

I was just testing my Matrox Millennium II with Jazz Jackrabbit on a Pentium MMX 200.

At normal CPU speed, the game's scrolling is very choppy, which makes it highly unpleasant to play. However, with L1 cache disabled via SetMul, it seems that the scrolling issue no longer occurs. I've seen that reported here, but now I can also confirm it myself. Jazz is fully playable on my system when slowed down like that.

Yeah, this issue is definitively related to CPU speed.

I just configured my Pentium MMX 200 to run at 100 MHz (2x50), and Jazz was perfectly smooth on the Matrox Millennium II. No scrolling problems whatsoever, and this was with L1 cache enabled. I also tried Epic Pinball and it was smooth as butter too. As for Commander Keen 4, enabling the "Fix Jerky Motion" setting from the in-game options completely resolves the scrolling issues in that game on this setup.

Bruno128 wrote on 2025-03-08, 19:13:

I think the whole “DOS compatibility” table from Gona should be taken with a grain of salt. It also doesn’t favor ATi because of some obscure edge-cases while they often do a good job at internal upscaling.

Agree, It's a very VERY useful list but by its very design only list the edge case games that cause trouble. It doesn't list the 100's of games that will work perfectly.
The idea is to check if any games in your library have compatibility issues. Not achieve 100% compatibility even for games that you know you'll never even run.

Joseph_Joestar wrote on 2025-03-09, 09:41:

Joseph_Joestar wrote on 2025-03-08, 12:29:

I was just testing my Matrox Millennium II with Jazz Jackrabbit on a Pentium MMX 200.

At normal CPU speed, the game's scrolling is very choppy, which makes it highly unpleasant to play. However, with L1 cache disabled via SetMul, it seems that the scrolling issue no longer occurs. I've seen that reported here, but now I can also confirm it myself. Jazz is fully playable on my system when slowed down like that.

Yeah, this issue is definitively related to CPU speed.

I just configured my Pentium MMX 200 to run at 100 MHz (2x50), and Jazz was perfectly smooth on the Matrox Millennium II. No scrolling problems whatsoever, and this was with L1 cache enabled. I also tried Epic Pinball and it was smooth as butter too. As for Commander Keen 4, enabling the "Fix Jerky Motion" setting from the in-game options completely resolves the scrolling issues in that game on this setup.

jazz was broken for me on a pentium 90 using the regular millennium (don't have a millennium ii to test). so i would test with higher FSB as well, and maybe there are different versions of the game out there.

auron wrote on 2025-03-10, 08:57:

jazz was broken for me on a pentium 90 using the regular millennium (don't have a millennium ii to test). so i would test with higher FSB as well, and maybe there are different versions of the game out there.

I was using the GOG release for my tests, but I did try the shareware version as well, and that worked fine too.

Also, I don't think the FSB value matters, since Jazz has no scrolling issues on my rig with the CPU at 200 MHz (3x66) but with SetMul CCD applied. This puts the system speed slightly above a 486DX2-66 per Phil's chart.

okay, went and tested this using my 4 mb millennium card with the latest 3.0 BIOS. with a p133@75 and setmul bpd vpd with L2 disabled, getting 7.9 fps in pcpbench, which it says is in the average dx4/100 range. ccd/dcd have no effect on this pentium 133, perhaps these are only for pentium mmx despite this not being mentioned in the setmul documentation.

anyway, with this setup, loading the first episode this indeed seems to have improved the scrolling quite a bit, compared to testing earlier with a p133. sprites still flickered a lot but this might be normal for this game, can't say for sure as it's been a while that i played it. after that tested with the p75 with everything turned on, which still seemed just slow enough to avoid that judder during scrolling.

however on a whim loaded episode 4 and that would show absolutely horrible judder right at the start, and the slowed down p75 would show the same thing. i then turned off both L1 and L2, resulting in a 1.4 fps score in pcpbench, which probably falls somewhere around 486dx20-25 range. with this, the stutter at the very beginning of episode 4 was quite a bit improved, but unsurprisingly the game itself will massively slow down at that point.

so it seems the speed range to use in this game with matrox cards might fall somewhere between dx-33 and dx2-66, although if it differs that much by what is displayed on screen, it seems likely that there will be some level later on that will be broken no matter what. so just swapping out the card is certainly a much saner choice.

by the way, i forgot how many strange options this game had - there is a /vga switch that does fix the stutter even on the p133 and also makes it run fullscreen 70 hz instead of that oddball 59 hz mode, however clearly the game speed is tied to that 59 hz so now everything is sped up, making that switch pointless unless the game wasn't twitchy enough before. then it seems the "pentium" and "dx-50" sound options just sound worse than the default, and there is some "slow" color animation mode which seems to do absolutely nothing.

auron wrote on 2025-03-10, 22:11:

however on a whim loaded episode 4 and that would show absolutely horrible judder right at the start, and the slowed down p75 would show the same thing.

I was previously doing my testing on the first level of Episode 1 (Diamondus) as that's the one I'm most familiar with. But since you've mentioned it, I have now also tested the first level of Episode 4 (Turtemple) and I did notice some scrolling issues there when using my MMX at 100 MHz. Instead, I set the CPU back to 200 MHz and then disabled L1 cache via SetMul L1D. This slowed my system down to slightly below a 486DX2-66 per Phil's chart (37.9 score in 3DBench2). After that, the scrolling issues in Episode 4 disappeared, and the game ran smoothly.

auron wrote on 2025-03-10, 22:11:

then it seems the "pentium" and "dx-50" sound options just sound worse than the default

Stargo and keropi made a fix for that. I didn't mention this before because it didn't seem relevant to the scrolling issue, but I'm using this fix and have the sound configured to "Ultra High Quality". With that, Jazz sounds pretty good on my SB16.