Homebrew Saturn emulation using Cotton/Guardian Force testing and debug

[Olinnae1]

"test_saturn" is just the file name used during the generation of the nsp file. The final generated file does not have this name.

Post automatically merged: Aug 24, 2025

Yes, just select "cotton2.nsp" and the display effect will also apply to the original aspect ratio. In addition, I don't know how the effect is when you use it, can you tell me about it?

When I use your edited Cotton2.nsp and select widescreen off, it works just fine and there is no menu screen

Thanks again!

Post automatically merged: Aug 27, 2025

I really wish the voids were resolved in our "Ultimate" version. That said, this list suggests that one—or possibly several—of these features might be triggering the crash on the Switch version. If I had to make an educated guess, I'd point to "CPU frequency" as the likely culprit.

I also suspect that. While I was trying to get 1.1 working, I thought it might be the fact that the game starts "Chaching data..." when you first boot it up, when it shows the hanging sonic sprite. Because it crashes immediately. Sega Saturn games don't really do that, do they? Not to my knowledge at least. I haven't even seen other rom hacks do that. but I'm not so sure because 1.0 does the same thing, but it just shows the hanging sonic sprite and doesn't actually say 'Caching data..." But I assume it's doing the same thing. After I got 1.0 working, I now think as you do and it's gotta be that boosted CPU frequency thing, right?

 

[dragonz]

When I use your edited Cotton2.nsp and select widescreen off, it works just fine and there is no menu screen

Thanks again!

Post automatically merged: Aug 27, 2025

I also suspect that. While I was trying to get 1.1 working, I thought it might be the fact that the game starts "Chaching data..." when you first boot it up, when it shows the hanging sonic sprite. Because it crashes immediately. Sega Saturn games don't really do that, do they? Not to my knowledge at least. I haven't even seen other rom hacks do that. but I'm not so sure because 1.0 does the same thing, but it just shows the hanging sonic sprite and doesn't actually say 'Caching data..." But I assume it's doing the same thing. After I got 1.0 working, I now think as you do and it's gotta be that boosted CPU frequency thing, right?

Yeah, 1.1 crashes on Switch because it pushes the emulator too far—CPU tweaks, input changes, and memory handling in the patch go beyond what Saturn2NSP can reliably support.

If I had to take another wild guess based on everything we know, I’d say Saturn2NSP lacks stable support for the 4MB RAM expansion, which is critical for running SOTN Ultimate 1.1 smoothly. That extra RAM is what the patch leans on to fix slowdowns, load assets more efficiently, and handle the deeper system tweaks like CPU frequency boosts and graphical restorations.

That said, there’s hope? if someone can isolate which specific feature in 1.1 is causing the crash—like the CPU boost or input remap—it might be possible to strip it out or tweak the patch for better compatibility. Until then, 1.0’s the stable fallback.

Did the devs ever release any beta builds of 1.1, or did we jump straight from 1.0 to the final patch?

EDIT: I've yet to try these settings by editing the \saturn2nsp\02 Saturn game settings\original screen 4MB ram\romfs
CottonBoomerang_Switch.ini


Fixing Castlevania SOTN ULTIMATE 1.1 Saturn Crash on Switch (Saturn2NSP)

Change CartridgeID from "5c" to "5a" or "5b" to improve 4MB RAM compatibility.

Set SH2Cache to 1 to enable better CPU emulation.

Set DelayVDP2RAMWriteTiming and VDP2RAMWriteTiming both to 1 to reduce timing-related crashes.

Set MeshTranslucent to 1 to restore transparency effects used by SOTN.

Lower SMEM3 from 5 to 0 or 1 to avoid memory conflicts.

I'm planning to test these fixes in Saturn2NSP v1.2. They've worked for others using custom Saturn NSPs, so I’m curious to see how they perform here. Feel free to try them out on the latest version of Saturn2NSP and share your results.

 

[ness151]

Yeah, 1.1 crashes on Switch because it pushes the emulator too far—CPU tweaks, input changes, and memory handling in the patch go beyond what Saturn2NSP can reliably support.

If I had to take another wild guess based on everything we know, I’d say Saturn2NSP lacks stable support for the 4MB RAM expansion, which is critical for running SOTN Ultimate 1.1 smoothly. That extra RAM is what the patch leans on to fix slowdowns, load assets more efficiently, and handle the deeper system tweaks like CPU frequency boosts and graphical restorations.

That said, there’s hope? if someone can isolate which specific feature in 1.1 is causing the crash—like the CPU boost or input remap—it might be possible to strip it out or tweak the patch for better compatibility. Until then, 1.0’s the stable fallback.

Did the devs ever release any beta builds of 1.1, or did we jump straight from 1.0 to the final patch?

EDIT: I've yet to try these settings by editing the \saturn2nsp\02 Saturn game settings\original screen 4MB ram\romfs
CottonBoomerang_Switch.ini


Fixing Castlevania SOTN ULTIMATE 1.1 Saturn Crash on Switch (Saturn2NSP)

Change CartridgeID from "5c" to "5a" or "5b" to improve 4MB RAM compatibility.

Set SH2Cache to 1 to enable better CPU emulation.

Set DelayVDP2RAMWriteTiming and VDP2RAMWriteTiming both to 1 to reduce timing-related crashes.

Set MeshTranslucent to 1 to restore transparency effects used by SOTN.

Lower SMEM3 from 5 to 0 or 1 to avoid memory conflicts.

I'm planning to test these fixes in Saturn2NSP v1.2. They've worked for others using custom Saturn NSPs, so I’m curious to see how they perform here. Feel free to try them out on the latest version of Saturn2NSP and share your results.

using 1.3 and setting a japanese bios file gets it to boot to the hanging sonic menu.

 

[dragonz]

using 1.3 and setting a japanese bios file gets it to boot to the hanging sonic menu.

That's the wall I've hit before as well.

 

[Monkey76083]

Would anyone know the answer to this problem:

I had about 10 saturn games working perfectly on switch 18.1E w/ atmosphere v1.7.1E. I have since upgraded to switch v20.3E and atmosphere v1.9.4E. My previously installed saturn games no longer launch and give this error "Unable to start software. Return to the HOME Menu and try again."

I figured I would need to rebuild the NSP's after re-dumping my keys with lockpick (latest version 1.9.15) but after doing so and installing an NSP, the icon is just a blank spinning icon. When launching, I receive error code "2123-0011" I have tried various different methods of building these with the same results. I am blocking NDS servers which this code seems to reference. Don't see how they are tied to this though.

For reference, I am injecting games using the ultimate switch hack script (the previous version I used before and I also updated to the latest version that stated it supported switch 20.4). I am using Cotton Boomerang as the base (same as with the games that worked previously) and I am strictly running via Emunand, switch 20.3E - atmosphere 1.9.4E.

Any guidance would be appreciated.

 

[hotcofe]

Would anyone know the answer to this problem:

I had about 10 saturn games working perfectly on switch 18.1E w/ atmosphere v1.7.1E. I have since upgraded to switch v20.3E and atmosphere v1.9.4E. My previously installed saturn games no longer launch and give this error "Unable to start software. Return to the HOME Menu and try again."

I figured I would need to rebuild the NSP's after re-dumping my keys with lockpick (latest version 1.9.15) but after doing so and installing an NSP, the icon is just a blank spinning icon. When launching, I receive error code "2123-0011" I have tried various different methods of building these with the same results. I am blocking NDS servers which this code seems to reference. Don't see how they are tied to this though.

For reference, I am injecting games using the ultimate switch hack script (the previous version I used before and I also updated to the latest version that stated it supported switch 20.4). I am using Cotton Boomerang as the base (same as with the games that worked previously) and I am strictly running via Emunand, switch 20.3E - atmosphere 1.9.4E.

Any guidance would be appreciated.

Check if the size of your game cover is larger than 100k. If it is, changing the size to less than 100k should solve the problem. This problem has existed since system version 19.0

 

[Monkey76083]

Check if the size of your game cover is larger than 100k. If it is, changing the size to less than 100k should solve the problem. This problem has existed since system version 19.0

The icon image was 1.4mb. I reduced it down to under 100K in both JPG and PNG formats. Unfortunately I still have the same issue.

 

[ghassanps3]

Thx for the effort how I can swap dick like game has multiple disc Sakura wars 2
Thx in advance

 

[dragonz]

Thx for the effort how I can swap dick like game has multiple disc Sakura wars 2
Thx in advance

I managed to simulate a disc swap by creating two separate NSP files—one for Disc 1 and one for Disc 2. Then, using DBI, I copied the in-game save data from Disc 1 and overwrote the save data for Disc 2. This allowed the game to continue as if the disc had been swapped.

 

[mspy]

The problem about the method that everyone is using here to run Sega Saturn games (making use of the emulator code named 'Zebra' that some Saturn games officially use to run on the Switch) is that the version of the emulator in question is an old version that came with the early releases by City Connection which for whatever reason was found to be unencrypted on the files hence easy to leverage.

Since then the 'Zebra' emulator which apparently is based on the already established Saturn emulator 'SSF' (making sense as to why some of the issues of SSF are also found on Zebra) got improved and updated to address among other things input lag concerns.

The later versions are said to be encrypted albeit I really doubt that anyone has checked every single game with every update to confirm it.

It would be nice to have one of the latest versions of the 'Zebra' emulator working here but oh well I guess no one with the know-how took this challenge.

 

[Timballisto]

Newb here. I'm trying to install Panzer Dragoon USA with Switch2NSP.

Do I need to install Cotton Boomerang, then dump the keys, uninstall Cotton, then use the script to make the NSP?

What do I need to change the ID of the NSP to in the script?

 

[Monkey76083]

Problem has been solved.

This ended up being an issue not solely related to running saturn games. I realized some other games that were working previously also would no longer launch. The solution was to use sys-patch in tandem with the updated sigpatches. I was already using the latest sigpatches but that was not enough. All games run properly now.

 

[Adrian1977]

using 1.3 and setting a japanese bios file gets it to boot to the hanging sonic menu.

How do you put the bios file?

 

[ness151]

How do you put the bios file?

mess with the .cfg file. You can call up different bios files there, and the emulator will read them. I wonder why the japanese bios file doesn't launch the game though, that seems weird to me.

 

[adrianomarcel]

Problem has been solved.

This ended up being an issue not solely related to running saturn games. I realized some other games that were working previously also would no longer launch. The solution was to use sys-patch in tandem with the updated sigpatches. I was already using the latest sigpatches but that was not enough. All games run properly now.

Good morning! Could you make these Saturn games available for Switch? I can't find them anywhere!

 

[mspy]

mess with the .cfg file. You can call up different bios files there, and the emulator will read them. I wonder why the japanese bios file doesn't launch the game though, that seems weird to me.

You tried with CAVE ? it has a option for that and more.

 

[The_Overseet]

Hey there guys, currently running into some issues. I'm trying to play Sakura Wars, particularly I'm doing it without using the magic packing tool script. A lot of the information now is kind of gone or hard to find. I've gotten Sakura Wars to boot and it plays without too much issue, but I'm looking into two things.

• 1: Disc swapping.
  
  I have no real way to test if the swapping will work properly or not from the place I am in the game, but I currently have both of them in the correct RomFS folder, and know that I can rename the discs to load the correct one potentially, though I'm not sure if this will actually be enough.
  
  Could I get some help on this? Someone mentioned something about using Simple Mod Manager or something too...
  
  
• 2: Magnification/Upscaling?
  
  There is a magnification setting in the .ini file, but for the life of me I cannot get it to work. Currently I'm using Cotton2 as the base, though I imagine I could get my hands on Guardian Force or newer Saturn titles as needed. Just want something that is not too rough to use/setup (I'm pretty technical but poking around without instructions is rough). Any help is appreciated, thank you very much.

 

[ness151]

You tried with CAVE ? it has a option for that and more.

no, I'm doing it manually.

 

[adrianomarcel]

Hey guys, I have some good news. I made some changes to saturn2nsp V1.3, and now it is possible to remove the menu icon in the lower left corner when in widescreen mode. If you want to try it, I can share it with you.

Hello good morning! I downloaded your modified version of saturn2nsp v.1.3 which removes the menu using cotton2! But when I clicked on create the nsp it says [Errno 2] No such file or directory: '.\\tools\\control\\control.nacp'! How to solve?

 

[hotcofe]

Hello good morning! I downloaded your modified version of saturn2nsp v.1.3 which removes the menu using cotton2! But when I clicked on create the nsp it says [Errno 2] No such file or directory: '.\\tools\\control\\control.nacp'! How to solve?

You can try to replace the rom file.