bad rom, checksum fail

[coinheaven]

so i opened up a rom in znes and it said it was a bad rom and checksum failed. any idea how to fix this?

[Bregalad]

If you are applying a ROM hack or a translation, it's normal that there is a "bad" checksums (hackers often intentionally don't fix it so it's not mistaken as a good dump). Only good ROM dumps have the right checksums.

I belive some comercial ROMs actually have bad checksums ! That's because the SNES, unlike the GB, has no BIOS or anything that checks if it's right and refuse to run the game if it isn't. So programers could as well not give a damn about the checksum and have it wrong.

[coinheaven]

If you are applying a ROM hack or a translation, it's normal that there is a "bad" checksums (hackers often intentionally don't fix it so it's not mistaken as a good dump). Only good ROM dumps have the right checksums.

I belive some comercial ROMs actually have bad checksums ! That's because the SNES, unlike the GB, has no BIOS or anything that checks if it's right and refuse to run the game if it isn't. So programers could as well not give a damn about the checksum and have it wrong.

ok, so a game can work on real hardware if it has a bad checksum?

[Bregalad]

Yeah, the SNES does absolutely not check it as it has no BIOS !
However a game like Earthbound might do stuff like doing it's own CRC check and refuse to run normally if hacked. I don't think many other games did this though.

[tepples]

Correct. The Super NES checksum appears to have been intended to ensure that the ROM data is not damaged between when it leaves the developer's hard drive and when the first retail cartridges with mask ROMs roll off the production line.

[coinheaven]

great, thanks for all the great info!!