Pseudo Saturn Kai official thread

Thanks for the info.

Any idea if I could just yank out the cart as soon as the game boots? Or would that not fix the issue / risk damaging something?
That might put the game in a playable state but I don't recommend it because the Saturn's cartridge port is not designed for swapping/removing carts while the system is powered on, so you risk damaging something if you do that (as you guessed).
 
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fafling

Gear Supporter
This isn't a Pseudo Saturn Kai issue; instead, this sprite glitching is the result of a conflict between your cartridge and the game. This type of conflict is uncommon but not unheard of (e.g. Die Hard Trilogy refuses to work with certain cartridges, regardless of what firmware is installed on the cart).
Do you have examples of Pseudo Saturn Kai cartridges that run Slam 'n jam 96 without that glitch ? Otherwise I wouldn't rule out an issue with the Pseudo Saturn Kai menu.

The Slam 'n jam 96 glitch is that VDP1 is in a state where it doesn't render untextured polygons with transparent pixel enabled (illegal setting according to VDP1 manual). This is the case of the framebuffer erasure polygon, which explains that sprite graphics from preceding frames remain on screen on the parts where the framebuffer is normally transparent to the VDP2 layers below the sprites :
1631817938851.png


Other games using untextured commands with transparent pixel enabled also have this issue when launched with Pseudo Saturn Kai (tested with original discs) : Need for speed (missing gauges and lower part of sprites not erased), and Croc (the fixed US version which doesn't have to be launched from the multiplayer).

I have checked the Pseudo Saturn Kai lite menu (v6.437), and it uses some texture addresses that are not aligned on 32 for the stars. They're 48 bytes textures and their adresses are aligned on 48 and may not be a multiple of 32 :
1631818958965.png


Such a texture address is also illegal according to VDP1 manual. Although it doesn't cause an immediate glitch, it may put VDP1 in an abnormal state and could explain the glitches when Pseudo Saturn Kai launches games that use other illegal stuff.
 
Firstly, let me enlarge on Die Hard Trilogy. A few years ago, I found that a legit copy of this game was not getting past the copyright screen when booting with an Action Replay 4M Plus cartridge via the following firmwares:
  • Action Replay stock firmware v2.02
  • Pseudo Saturn Kai Lite v6.317
However, that same copy booted fine with Pseudo Saturn Kai Full v6.317 installed on the Saturn Gamer's Cartridge, hence why I confidently declared that Die Hard Trilogy does not like certain carts. And today, I confirmed that by finding that it also doesn't work with my Action Replay cart with the boot ROM completely erased.

Shortly after testing Die Hard Trilogy, I heard about this glitch with Slam 'n Jam. If I remember correctly, I experienced this glitch when loading the game on my Saturn equipped with Phoebe ODE via the following methods:
  • Boot Pseudo Saturn Kai Lite installed on Action Replay -> Load game
  • Boot Pseudo Saturn Kai Lite installed on Action Replay -> Load Rmenu -> Load game
Based on these results I probably thought to myself, "This glitch occurs even when Pseudo Saturn Kai doesn't directly boot the game, so it can't be responsible". Combining that thought process with a) the knowledge of the Die Hard Trilogy glitch, and b) my lack of knowledge on VDP1, I rushed to the conclusion that something similar was causing the issue with Slam 'n Jam. Well, that assumption was wrong because I did more tests today on my Phoebe without any cartridge inserted, and got the following results:
  • Rmenu v0.2 [Fast Boot] - Usually works fine, but sometimes the glitch occurs
  • Rmenu v0.2 [Full Boot] - Works fine
  • RmenuKai v6.437 - Glitch occurs with both CWX and JHL loaders
tl;dr It looks like Pseudo Saturn Kai's menu* causes graphical glitches in Slam 'n Jam, and has nothing to do with any type of cartridge being inserted.
* and sometimes Rmenu when using Fast Boot

Do you have examples of Pseudo Saturn Kai cartridges that run Slam 'n jam 96 without that glitch ? Otherwise I wouldn't rule out an issue with the Pseudo Saturn Kai menu.
I had it in my mind that the game works fine with the full version of Pseudo Saturn Kai installed on the Saturn Gamer's Cartridge, but that's not true because the glitch also occurs with that. I was probably conflating it with Die Hard Trilogy which does work fine with the Gamer's Cart.

I have checked the Pseudo Saturn Kai lite menu (v6.437), and it uses some texture addresses that are not aligned on 32 for the stars. They're 48 bytes textures and their adresses are aligned on 48 and may not be a multiple of 32. Such a texture address is also illegal according to VDP1 manual. Although it doesn't cause an immediate glitch, it may put VDP1 in an abnormal state and could explain the glitches when Pseudo Saturn Kai launches games that use other illegal stuff.
This is really useful info, thanks for providing it. Hopefully @cafe-alpha can re-work the star textures in order to ensure that VDP1 is not adversely affected.

Other games using untextured commands with transparent pixel enabled also have this issue when launched with Pseudo Saturn Kai (tested with original discs) : Need for speed (missing gauges and lower part of sprites not erased), and Croc (the fixed US version which doesn't have to be launched from the multiplayer).
Thanks for this info too. According to this post on reddit, Mechwarrior 2 and Space Hulk also have graphical issues with Pseudo Saturn Kai, perhaps for the same reason?

Screenshot 2021-09-17 at 11-02-33 r SegaSaturn - Comment by u Cabal17 on ”Game graphics buggin...png


If you have one, could you possibly PM me a link to the fixed US version of Croc? I've heard about this version but it's not on Redump and I can't seem to find it anywhere else.
 

fafling

Gear Supporter
Interesting about Mechwarrior 2 and Space Hulk glitches with Pseudo Saturn Kai, I didn't know.

I'm off for 3 days, so can't check right now, but iirc the redump US version of Croc is the fixed one. I compared its settings for the polygon commands and it was the same as those made by my US CD (only transparent pixel enabled while the bugged PAL CD enables transparent pixel and end code, illegal combo ! ). Apparently there was a recall of the US bugged version, so it must be quite rare.
 

cafe-alpha

Established Member
Thank you @fafling for the remark about data alignment ! So far I thought sprites had to be aligned to an 8 bytes boundary but I was probably misunderstanding with restriction regarding width of the sprites.

Data alignment is fixed on latest (WIP, not public) build and I hope it will fix the glitch with Slam'n Jam
20210919_starfield_64b.png
 
I'm off for 3 days, so can't check right now, but iirc the redump US version of Croc is the fixed one. I compared its settings for the polygon commands and it was the same as those made by my US CD (only transparent pixel enabled while the bugged PAL CD enables transparent pixel and end code, illegal combo ! ). Apparently there was a recall of the US bugged version, so it must be quite rare.
Yep it's the fixed version, thanks for the tip. On my Phoebe ODE it loads fine in Rmenu (Fast and Full Boot) but is glitched when loaded by Pseudo Saturn Kai.
 

fafling

Gear Supporter
Thanks for this info too. According to this post on reddit, Mechwarrior 2 and Space Hulk also have graphical issues with Pseudo Saturn Kai, perhaps for the same reason?

View attachment 6611
Yes, same kind of issue in Mechwarrior 2 and Space Hulk : the missing graphics are drawn with line commands with transparent pixel enabled.

Interestingly, in Space Hulk, the map doesn't appear during the first briefing, but then in game it appears correctly, and if you exit the mission and go to select mission to display the briefing again, the map is displayed. In all cases, the map is drawn with the illegal line commands.
So Space Hulk seems to do something that allows VDP1 to resume the drawing of those illegal commands when gameplay starts.
 
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