GameShark Pro shenanigans

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marshallh
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GameShark Pro shenanigans

Post by marshallh » Thu Apr 30, 2009 9:03 pm

I got a GameShark Pro 3.2/3.3 for free from a friend. Doesn't work.

You can revive them by piggybacking them onto a working one, connecting them to a PC, and flashing the BIOS on them. I don't have a second one, though.

99% chance the problem is with a corrupted flash ROM. This happens when you delete too many cheat codes at once.

The board on the left is a board I designed a couple years ago as a general purpose USB microcontroller protoboard. It's hot-glued to the Gameshark board for stability.

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When the Gameshark boots, it loads in its own 256kb program. This is stored across the two flash chips, I dumped one so far. It's missing every other byte, so I think the two ROMs are wired together and the /CS chip select line is used as the least significant address bit.

More progress later tonight...
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Re: GameShark Pro shenanigans

Post by stuntpenguin007 » Thu Apr 30, 2009 9:50 pm

nice job on finding the most complicated way to recover a gameshark :D
hope it works.
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marshallh
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Re: GameShark Pro shenanigans

Post by marshallh » Thu Apr 30, 2009 11:36 pm

success!!! I got the rom dumped (hopefully) right.

Turns out both flash ROMs share the address bus and OE/CS. They're set up so that one chip provides each byte of the 16-bit word. This is because the N64 PI cartridge bus is 16bits wide. Nifty.

Ran some more lines for the other chip
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Here you can see some of the game listings
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The entire file is basically a N64 rom, except the first 4kb are empty (that's the Nintendo copyrighted boot block, which is substituted with the one you have plugged into it).

However this dump has a bunch of garbage strewn around the first 4kb when there shouldn't be. I'll try flashing it with a known good Datel dump tomorrow
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Re: GameShark Pro shenanigans

Post by Skyone » Thu Apr 30, 2009 11:54 pm

marshallh wrote:99% chance the problem is with a corrupted flash ROM. This happens when you delete too many cheat codes at once.
What type of error did this cause? What, it just didn't boot up at all because it was reading invalid memory? How the hell did Datel manage to mess up that bad? :lol:

Nice job, regardless. Let us know if you find anything more interesting. :P

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Re: GameShark Pro shenanigans

Post by codeman » Fri May 01, 2009 8:47 am

Analog electronics are way cooler than Digital electronics!

Ok...that is pretty cool, I'll admit it. Is there a way to update the firmware of the gameshark using this method? Or are there no further updates beyond the 3.3 version?
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Re: GameShark Pro shenanigans

Post by ShockSlayer » Fri May 01, 2009 1:50 pm

Is the n64 rom replaceable? :twisted: Not likely.

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Re: GameShark Pro shenanigans

Post by stuntpenguin007 » Fri May 01, 2009 2:16 pm

hmmm I've got a currupt gameshark, maybe I should try this. jk I'll stick with using another gameshark to fix it.

But great job on this
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Re: GameShark Pro shenanigans

Post by marshallh » Fri May 01, 2009 6:38 pm

Something is wrong with either my physical wiring (address lines) or a problem with my read function.

I write the image on the left, what I read back is on the right.

The first 2k (small strip at the top) is correct, after the 2k it goes to hell.

Image . . . . . . Image
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Re: GameShark Pro shenanigans

Post by marshallh » Fri May 01, 2009 7:43 pm

Got my read routine working. The timing was too aggressive and it wouldn't let the chip catch its breath after reading X number of bytes. Slowed down the timing and it read without a hitch.

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Oh, and the GameShark boots up now after being re-flashed with a good official copy of decoded ROM :D
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Re: GameShark Pro shenanigans

Post by Skyone » Sat May 02, 2009 2:03 am

So what are you gonna use the Gameshark for? Cheating? :P

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Re: GameShark Pro shenanigans

Post by ShockSlayer » Sat May 02, 2009 7:45 am

Skyone wrote:So what are you gonna use the Gameshark for? Cheating? :P
:lol: Its marshall, I'm sure he has a better idea.
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Re: GameShark Pro shenanigans

Post by Dark-Aries » Sat May 02, 2009 11:20 am

I bought two used GS...one without the parallel slot, the other with. and when I learnt theer is a program to relfash it..I CNA"T FIND THE ONE WITH THE PARALLEL PORT!!!!



Now if I only had you like two steps away to fix my gs...:)

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Re: GameShark Pro shenanigans

Post by stuntpenguin007 » Mon May 25, 2009 7:33 pm

any chance you could hook me up with the dump of those flash roms? I'm going to write to the flashroms with my computer, because it has a socketed bios flash rom thing.
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Re: GameShark Pro shenanigans

Post by marshallh » Thu May 27, 2010 8:44 pm

Bump from the dead. Tried booting the gameshark with the FPGA cart emulator. Bad idea.

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Re: GameShark Pro shenanigans

Post by metalcookie » Thu May 27, 2010 9:13 pm

marshallh wrote:C:\Documents and Settings\Boris\My Documents\poop
:mrgreen:

I hope you get this little snag fixed. This is turning into a real interesting thread.
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