Hacking Help with GBA Multicart Backup

[marcelbruer]

I have the 369-in-1 multicart and I would like to use Rudolph's Backup Tool to rip the ROM from the cart as well as replace the Pokemon Emerald save file with another completed file from an emulator. However, when I try to import the ROM it pulls up the multicart menu but the games don't load. Does anyone have any experience with multicarts or know how I can put a new .sav on the cart?

 

[FAST6191]

Short version. Probably time to invest in a proper flash cart.

Longer version
While I am fairly up to date on the stuff used in straight up pirate/repro type carts I am less familiar with the multicart side of things and I doubt there are many out there that are going to be able to help -- they are not very common, not very usable and usually about as unreliable as it gets so people don't put the effort into them. Owing to the way GBA games work I can make some guesses as to the happenings but it is not going to result in a "download this"/"follow this list of steps" type thing. In all likelihood it could be reduced to a "download this DS homebrew" type thing but it is going to take a fair bit of work to get to that stage.

I assume "369-in-1" is advertising speak for "20 games but a lot of cheats/hacks for the others" or "5 games and a massive collection of emulated games". It matters little but in the case it was actually 369 games then that would change things quite a bit.

If the multicart is a slight twist on a flash cart then its original software might help, though that will also tend to want its original hardware as well which probably did not come with it. Straight pirate/repro carts moved on from rebadged flash carts some time ago but again I am not sure what would happened for this sort of thing.

After this it will likely be different to most other games, however the key word is most. Two main choices being https://mgba.io/2015/10/20/dumping-the-undumped/ with a window or a return to the flash cart side of things, said flash cart would either be a NOR era style thing or massive RAM thing but setting pages or a more modern flash cart thing of copy to and from a NAND memory section on game selection. The linked stuff is for dumping games but the same principles apply and you will have to figure out the swap or change window command for the save section (or ROM section if you want to dump the ROMs it has).

The crazy man method would be open up the multicart, see what it has as far as save storage/handling. Dump that by something soldered onto the relevant pins, find out where the pokemon save is in it, overwrite in dump, flash modified dump back to the multicart. If you know someone of the electrical engineering persuasion then they would probably opt for this for such a small alteration.

 

[marcelbruer]

Some more info: I spent an hour monkeying with the cart on Friday and using GBA Backup Tool I am able to copy both the ROM and the .sav from the cart and put them onto my computer. GBA Backup Tools will identify the multicart as being the most recent game played; thus if I start up Pokemon Emerald on the multicart in slot 2 of my DS then turn it off and boot up GBA Backup Tools on my slot 1 flash cart I can access the Emerald ROM and save file located in the multicart. The ROMs of the GBA pokemon games seem to be altered from the originals, as when you first start them they display a message that says "the save will be loaded" and another that says "the game can be played." I figure this message is just a text edit of the "the save battery has run dry" message from the original games, seeing as the multicart has no battery for RSE's real time clock. As a result, the .sav files pulled from the multicart are incompatible with an emulator and with PkHex, rendering my little project impossible. I can play the hacked ROM in an emulator, which is interesting due to the altered text and the ROM being unable to save: when you try to save in-game it brings up an error screen that I've never seen before. I assume this is because the save paths in the ROM have been edited to work with the multicart's memory; I don't know much about the hex code but there's probably evidence in there.

I embarked on this project because my friend and I want to play through the Battle Frontier on Pokemon Emerald and he doesn't own a physical copy of the game but does have the 369-in-1 multicart which contains every GBA pokemon game. Here's a picture of that cart's board: the multicart is on top, another pokemon hack game I own is in the middle and my legitimate copy of Emerald is on the bottom. It appears that the two bootleg carts have similar, if not the same, boards. Does this shed any light on what sort of memory the multicart has, and are these carts reflashable?

https://imgur.com/a/PzG5a2J

 

[FAST6191]

That looks like the modern style epoxy blob reproduction type cart. I did not know they had extended it to multicart.

We did mess around dumping some games in another thread. Some fairly extensive changes, including to the save handling, were performed https://gbatemp.net/threads/reflashing-gba-bootlegs-cant-save.483345/
I am not sure it is changed based on your messages though -- those look like normal messages you get when the save gets broken somewhere along the way.

Anyway I would be somewhat surprised if the save does not work in an emulator with an original version of the game. Fiddling with save methods, text and whatnot is easy enough but messing with the save is usually a lot of work for no great gain. Though if it also does not work with a save editor there might be something up...
If you know how to use a hex editor (by and large it will be like a word processor or whatever you wrote this thread on, which is to say copy, paste and delete work as you might expect) then maybe generate a save normally (start a game, get a pokemon and save). After that take the save from the multicart, chop off the first few hundred bytes and the reverse for the normal save, put them together. For the thread above they altered some of the serials and whatnot and that is possibly what is tripping up the save editor program. If it sees a normal save at the start then it might be able to push through it (again altering save setups is a lot of work and repro cart makers don't like doing work), at least enough that you can read the state out of one game and copy it into another.