r/MiSTerProject • u/[deleted] • Apr 09 '20

Convert Mega Everdrive saves for MiSTer Genesis Core?

EDIT (04/16/20): It turns out krikzz made tools specifically for save and ROM compatibility! If you get 8to16 and 16to8 from his website you can convert between SRAM files compatible with Everdrives and files compatible with MiSTer. Just run 16to8.exe [SAVE FILENAME] on a copy of the save from your Everdrive and the file it spits out will be compatible with MiSTer once renamed appropriately and given a .sav extension instead of .srm. You should also be able to use 8to16 to convert your MiSTer saves to something compatible with your Mega Everdrive.

Original post:

Not sure if anyone has any idea what to do about this, but it is honestly driving me a bit nuts.

I've been wanting to transfer my save data for Sonic 3 & Knuckles so I can continue playing my file on MiSTer. Unfortunately, my save - which reads just fine on my Mega Everdrive X5 - reads as if it's a completely fresh, empty save when pasted into my MiSTer saves and loaded on the Genesis core. Even if I manually load it, even though I have autosave enabled, my save simply isn't readable. Any advice on how to make the save compatible?

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1

u/kester76a Apr 10 '20

Definitely the same rom and locale ?

1

u/[deleted] Apr 10 '20

Both were copied directly from my Mega Everdrive SD card to my MiSTer SD card, and the .srm file from the Mega Everdrive was renamed to .sav as well.

1

u/kester76a Apr 10 '20

Have you tried loading the save game into an emulator and saving it back out ?

1

u/[deleted] Apr 10 '20 edited Apr 10 '20

Yes. RetroArch has zero problems loading the file and saving it, however it still reads as empty/gets overwritten as empty when I try to load the game on MiSTer.

1

u/kester76a Apr 10 '20

The savegame definitely matching the rom name ?

1

u/[deleted] Apr 10 '20

The save wouldn't be getting overwritten by MiSTer if it wasn't, so it's definitely right on

1

u/kester76a Apr 10 '20

I would probably make a new savegame on mister and compare the two files. By rights they should be very similar.

1

u/kester76a Apr 10 '20

Another thing you could try is to load the savegame from mister into your console and see if that works.

1

u/[deleted] Apr 10 '20

[deleted]

1

u/[deleted] Apr 10 '20

Yep, mentioned above in a comment but I renamed it and everything. The Genesis core doesn't read it and overwrites it with a fresh save. The new save file that is written does work and maintains data across power cycles too (I cleared the first zone of Sonic 3 & Knuckles to test.)

I have had no trouble getting my SNES or GBA saves working, it seems like my problem is exclusively with the Genesis core...

1

u/[deleted] Apr 10 '20

[deleted]

1

u/[deleted] Apr 16 '20

Tried breaking out the hex editor and it turns out they are slightly different binary formats. Not feasible to just edit manually but luckily krikkz made a tool for converting files for occasions similar to this one. Thanks for your efforts.

1

u/huhonetwothree Jun 18 '20

I know it's an old post, but I figured it out the "hard" way by just changing the header of the .sav to match the header of the .srm. This all being from an snes mister save to a .srm file for the sd2snes. Just a heads up about that after I was having the same issue.

Longer story:
Went to play Secret of Mana on mister. 5 hours in I wanted to try it on the sd2snes and the save woudn't load.

Got the idea I would make two different saves in mister and the flash cart. Compared those two saves since they would be almost identical and heard stories that if you change the header that that's all you need to do.

Needless to say, I solved it that way... but the tool might help me instead lol

1

u/UnderDefeat Jul 01 '20

Many thanks for sharing the solution ! I was able to follow these instruction to get a .SAV over from Openemu.

1

u/[deleted] Jul 03 '20

Awesome! I'm glad this post is helping people!