nesdev.org

My first post in quite some time now... I need to find some time for SNESdev.

I bought Yoshi's Island for my girlfriend, on eBay. We played it for a couple of months on/off, when suddenly a strange thing happened. The image on the TV was "zapped", as if a tiny burst of current distorted the picture somehow. I have no idea about electronics so far, you'll have to excuse the lay lingo.

I knew this was bad. When I went to the menu, I found that our savegames have been deleted. That really sucked. Now... I would like to positively ensure that when we go about trying to do 100% on each level the second time, we never have to do that again unless we want to. That can mean anything from using my father's GALEP to program the chip in question (is that the SRAM?) with a backed up copy of the saves or buying the Mash Mods programmer thingy (I would also like to back up my Zelda saves from my childhood with zero tolerance for possibly botching it up, so maybe this is the best way to go).

I understand that the smallest chip in the Yoshi's Island cart is a "reset IC" used to preserve the backup battery for as long as possible while receiving juice from the power supply. Maybe that cooperation between the 61029A (MM1026AF, dunno which one I should use - the former label is on the chip, the latter on the PCB) was what disrupted the saves?

So. If there is any way I can perpetually back up the saves by using my SNES PowerPak and/or my father's GALEP programmer, I would really like to know about it. I'm just trying to save $62.50 on buying a programmer I have no other uses for.

My saves were lost twice the same way, once the cat rubbed against the cart and the game froze, reset and it was empty, and in another they battery died.

I don't think an IC programmer is much help, it would take some serious finesse to desolder the RAM without it losing power. Maybe it could be read in-circuit, but not without modifying the board in a big way (I'd think).

Something like that 'Retrode' USB cart port may be usable, but it seems to cost 59 euros ($75). I don't know if the battery RAM on that board is any different from the other ones though. Retrode maybe could do it anyways, with the right firmware. I would guess the SNES PowerPak will not be supporting the FX2 chip anytime soon.

Maybe just eject the cartridge and store some SRAM reading/writeing code into the RAM of the system. I know you can do this for the GBA, maybe the SNES too.
Interrupt vectors might be a complication, haven't read through the SNES manual, but I bet you could disable interrupts.

You definitely would want a device wired to a SNES cartridge port that simply allows you to dump/write data with the cartridge. It really shouldn't be that hard and maybe one of the devices out there can already support Super FX cartridges.

Oomph... Seems I'm in over my head.

Dwedit, no way would I be able to do something like that, I'm afraid.

The Mash Mods programmer does say (in the manual) that you can write backed up saves to all cartridges. That should work with this one too, right? I don't see why the SuperFX would interfere with the procedure.

If anyone has any other plausible idea for walking me through or pointing me to any solution, please don't hesitate to do so.

you don't have access to the SRAM directly from the cartridge bus, it's connected through the super fx chip and that could be a problem, however the superfx chip should just bridge the connection when it hasn't been initialized but i don't know if thats just for the rom or if its for the sram too.

looks like retrode does supports it ( http://www.retrode.org/wordpress/docume ... ble-games/ ) but you might want to contact the developer since it's not really obvious if it really does...

it's hard to pinpoint what caused this problem but it sounds like a voltage spike from the power line. even if it was the 61029a that failed it would be hard to replace i've tried to find those myself but with out any success.

if you really think it's worth trying to rescue the game save:
1, email the retrode guy and ask if it supports superfx games
2, if so buy one and backup whatever is left of your saves
3, take a look at the sram-file with a hexeditor and see if there is any information or if everything is gone
4, if there is stuff in there, run the game with a clean sram-file in an emulator, save a game and check if it has some kind redundancy (i have heard that snes games should store the saves multiple times in case of random data loss)
5, if it has some kind of redundancy check your backed up file for the same pattern and try to change the data where it doesn't match, either by brute force or voting algorithm
6, when done repairing it, pray to what ever god you believe in and try if your game work in the emulator
7, if it does work, copy it back to the cartridge and play your game
8, if it does not work, or if any of the other steps failed; cheat your way through the game until you are at the same place as before (via a hexeditor or if you find a better way )

hyarion wrote:1, email the retrode guy and ask if it supports superfx games

Star Fox and Stunt Race are listed as compatible on the page you linked.

The list makes it look like all games should work unless they use the SA-1 which for the US is only used in very few games, Kirby Dreamland 3, Kirby SuperStar, and Super Mario RPG. Yoshi's Island is on the list as tepples said.

sure Yoshi's Island is on the list, hence supported but it doesn't say if _everything_ is supported or if it's just reading the ROM (which was the main purpose of the device) that is supported :/ (the other column basicly just says that it has SRAM, nothing more... at least that's how I'm interpreting it)

Thanks, guys, I'm a bit smarter now. 8)

I don't think I'll be getting Retrode any time soon, the coolness factor of it aside. It's too expensive for what I need. 75€ with the shipping.

The Mash Mods programmer is much cheaper ($62.50 with shipping). That I might think about. Any ideas on whether it'll support the SuperFX? If not, I'll email the head honcho over there.

Cheating through Yoshi is a good idea, but I would like to have a more permanent solution for saving data from any SuperFX carts I might get in the future.

No idea if Mash-Mods support Super FX dumping and SRAM dump/write functions. But I imagine if you email you should be able to get an answer to that. I would imagine if it doesn't they could possibly update it so that it would. Really SA-1 is the only really complicated cartridge to mess with due to the SA-1 locking you out if a SNES CIC isn't talking to it.

Yoshi's Island is one of the top 5 SNES games, and it's very much worth replaying many times, so I wouldn't worry about this one instance of lost progress (though having to redo Poochy Ain't Stupid perfectly will be a challenge). My SNES used to be very sensitive to the cartridge shifting, and I regularly lost games. You should try to first see if you can reliably cause glitches by jiggling the cartridge while it's on, then see if you can eliminate what's causing it, perhaps cleaning the cartridge connector. Once you have it reliable, then you can begin playing again.

@MZ: Thanks for the clarification!

@blargg: Great suggestion for the connector, thanks! I'll be sure to try it. Don't worry, I realize how good Yoshi is (and so does my girlfriend, it's her #1 game, so that's actually why I'm asking about it ) - it's just difficult to get through if we can't save our game, especially getting through with good scores.