Loading other Genesis roms in Sonic 1 3D?

I've been hopping around google looking up how to do this. I haven't found many specifics, but I do have an idea of how. I have a 3ds that can run homebrew with HANS and an untouched .cia file for the game. I just don't know how to extract the romfs and insert my rom of choice. HANS appear to allow running the already installed game with a new romfs, so it seems like that should be all that I need.

Does anyone have experience with this? I just want a nice way to play Sonic hacks on the go, and sadly, the existing 3ds homebrew emulators are far too slow to reasonably use (yes, there are phone emulators, but I'd rather have buttons ).

P.S. If you feel this is in the wrong place, feel free to move it.

 

You need a tool called ctrtool to extract .CIAs. Put the .CIA in the folder with ctrtool, and then do this in command prompt:

There will be a folder called 'romfs' with all of the file's you're looking for.
Since you're injecting custom ROMs, I would use Sonic 2 3D. That seems to accept custom ROMs much easier than Sonic 1 3D or any of the other SEGA 3D Classics. Also, don't expect the custom ROM to be in 3D.
Believe me, I've researched, disassembled, and overall torn down the Gigadrive emulator. It's not as simple as it may appear to be.

 

Thanks for the swift reply! I originally planned to use Sonic 2 3D (I remember someone else recommending it) but it won't work with HANS (it freezes on a red screen at the bottom when starting).

 

Well... can you install .CIAs? If you can, you can just modify the .CIA itself and install that with no problems.

 

I don't think so... I tried to do something that would install a .CIA file, but it said I didn't have kernel access.

EDIT: Also, ctrtool, when given that exact set of commands, and placed next to an appropriately named .CIA file, works at first, making two files, but then fails for the last four commands, outputting "unknown file" and causing the command following to fail as well, as no files are generated. It does this twice, once for exefs, and once for romfs.

EDIT2: Also heard that .CIA files can be encrypted. How would I decrypt it if thats' the case?

 

FYI the Picodrive CIA emulator runs at mostly full speed on my old 3DS. Gen Plus GX chokes, though.

 

@Pacguy, try following this guide to gain kernel.

Also, @Clownacy, you're correct. There's also a .3DSX version of Picodrive IIRC, so you could also use that if you wanted to Pacguy.

 

Last I heard, the CIA versions were faster, and it had something to do with Picodrive's dynamic recompiler.

 

That is also true. Dynamic recompilation isn't exactly possible without kernel access, so it isn't going to be as fast as the .CIA version. However, coming from just now testing the .3DSX Picodrive on my O3DS, I can say that it's still pretty playable.

 

Thanks! I'll definately check that out. To be honest, I haven't tried every emulator yet, and google searches of the emulator sound at least somewhat promising.

I appreciate the tip, but I don't really want to mess with my 3DSs' firmware. Hours of work, with every step being potential for bricking, its' just not my thing...

Also, I managed to get the romfs from Sonic 1 3D through braindump, and now have it decompiled on my PC. I know that "Sonic1.SGD.m" and "Sonic1_USA.SGD.m" are the rom files, but either they're missing header data, or there compressed somehow. Running them in a regular emulator obviously doesn't work, and when I search for key words from the header in a hex editor, I find nothing...

 

Ah yeah yeah, I forgot.
The ROMs are compressed in an MDF filetype. I have a compressor/decompressor, but I'm not home right now so I can't really get it for you. Maybe just Google around and see if you can find one.

 

Any suggestions on key words to search? I keep getting stuff on SQL server and some form of physical board . I tried looking up some stuff specific to rom injection for the 3ds as well, and didn't find much...