SNES Rom Hacking Question

[kai123]

Does anyone here know how one would go about making a SNES rom think it is another game? What I mean to say is that I have a SNES copier and would like to try and get the info from one cart to another. Not the actual data but the info that tells that cart it is that cart. If that makes any sense at all. I have been reading some of the SNES Dev book but have hit a wall so to speak. Header hacking seemed to be the way in but didn't work. Thanks!

[Kitsune Sniper]

... it doesn't.

What exactly do you want to do? And to what game?

[kai123]

I have convinced myself that I can get Star Fox 2 to run on the Super UFO 8 SD. I know you can run the same game from the same cart off of DRAM when using Super F/X games. I would like to take the info from what ever makes a .SMC file say that it is this cart to merge that info to Star Fox 2. I hope that is clearer. I might be crazy tired and wasting my time though. At least I can say I gave it the old college try.

[badinsults]

Star Fox 2 won't work on your copier because it requires the Super FX chip. No amount of hacking will allow the game to work on it.

[kai123]

Star Fox 2 won't work on your copier because it requires the Super FX chip. No amount of hacking will allow the game to work on it.

I am fully aware of that. If I can load other Super F/X games like Doom and the original Star Fox with the original carts but from DRAM something is telling that ROM that it is that particular game. Seems plausible to me.

[Kitsune Sniper]

Star Fox 2 uses a different version of the chip. I'm guessing this chip prevents what you want to do from working.

[kai123]

Star Fox 2 uses a different version of the chip. I'm guessing this chip prevents what you want to do from working.

Yes it does it uses the F/X 2 chip which is what is in doom. I am sure my mission is useless but why not kick it around? I got some time.

[MottZilla]

Because of the way the Super FX connects to the MaskROM in the cartridge there is no way without serious modifications to allow a copier to run a Super FX game. People have thought about running Super FX and other games on copiers for over a decade. There is no simple way to do it. If you want to play Star Fox 2, use an emulator, otherwise you need to take an actual Super FX cartridge and replace the MaskROM with a suitable memory containing Star Fox 2.

Also be aware there is no "Super FX2" as people often claim. It also isn't true that Star Fox 2 uses the same Super FX version as Doom. It does not require that. Star Fox 2 will run on either GSU-1 or GSU-2. Those versions of the Super FX are in every Super FX game cartridge except for Star Fox and the Star Fox Competition Weekend which use a version called the Mario Chip. The differences between versions of Super FX are simple.

Mario Chip. Cannot run in High Speed Mode.
GSU-1. Supports High Speed Mode.
GSU-2. Supports 16 Megs of ROM.

The only other differences between games are, some games contain battery backed SRAM, others do not. Some games contain more SRAM than other games. The chip versions are backwards compatible as they are the same chip with the minor differences described above. The big misconception is that the GSU-2 used in Doom is faster than the GSU-1 used in games like Stunt Race FX. It is not, it is the same speed.

One other misconception I've noticed is people think that building a reproduction/bootleg of Star Fox 2 cost alot of money. This is not true either, all the parts needed to make a bootleg could be obtained for $20 or less. The only thing true people say usually, it is more difficult to make than other games due to the surface mounted MaskROM opposed to the classic DIP which is much easier to work with.

[kai123]

Yea, I know all of that. I am just wondering why this particular copier will allow the back up of a cart to be played as long as the cart up top is the same as what is loaded in DRAM. I want to know if the copier is just playing the cart when it realizes that it is SuperF/X. Or if it is actually pulling the data from the cart and the data that is on the cart just happens to correspond with what the copier is loading. I am more interested in how the copier functions.

[MottZilla]

I understand what you are saying now. Yes some copiers might run a loaded Super FX image if the same game cartridge is plugged in. But you cannot ever get it to run a different game as the Super FX chip will always access the data from the ROM inside the cartridge and never the DRAM inside the copier. You cannot do any sort of hacking to get around this issue. It may be possible to patch the 65816 cpu code which may execute from DRAM in that case. In the end the answer is still the same. You cannot play Super FX games on a copier without an actual cartridge which defeats the point.

If you'd like to play those games, get the real carts or in the case of Star Fox 2, emulation or a homemade cartridge. The SD2SNES eventually may support Super FX via FPGA simulation of the Super FX.