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Same ROM, different File?! 
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Joined: Sat Mar 20, 2010 5:27 am
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Post Same ROM, different File?!
I wonder how the rom-files are organized. I have some files, which GoodSNES tells me are the same - but their filehash differs.
Somehow Goodsnes seems to ignore padding or metadata?!
If it's just padding, is there a tool which automatically strips the padding? (and only the padding) or (if needed for ZSNES & Co) replaces the padding of all files by the same pattern? (e.g. just 0s)

same applies for other ROMs, too (.z64 and .v64 for example) - but I think this is the wrong place for discussing non-SNES formats :)


Last edited by bugger on Thu Jan 17, 2013 12:03 am, edited 2 times in total.



Wed Jan 16, 2013 6:31 pm
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Post Re: Same ROM, different File?!
Could be different copier headers. I don't know the details of how goodsnes's hashing works, though.

But nowadays, goodsnes is quite outdated, and you should probably use something like no-intro or TOSEC DATs.

As for removing copier headers, there's all kinds of tools for that, or you can just manually chop off the first 512 bytes. For scrubbing, that's a bit more complicated. SNES ROMs don't really have much of a standard data organization or filesystem so that really can't be automated like on later platforms that either require the use of a standard filesystem or at least see widespread use of a standard filesystem.

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Wed Jan 16, 2013 7:07 pm
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Post Re: Same ROM, different File?!
outdated? Are there still new ROMs which appear from somewhere?!

I read about copier headers in between the posts - is there any use? HiROM/LoROM can be detected by the rom itself - waht about the save-RAM size?

If these headers are not usefull at all, I'd use the commandline version of NSRT to strip all the headers.

Does hiROM/LoROM depend on the game or is this chosen by the copier?
Or is there one "most common" to use ?

basicly I don't want to store the same rom twice, just because of crappy useless differences, which only the hash sum cares about :)


Thu Jan 17, 2013 12:02 am
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Post Re: Same ROM, different File?!
Yes, there are new dumps coming out, where previous dumps that were thought good actually turned out to be bad.

Also the headers aren't used by emulators. Those things are automatically detected. The details I'm not familiar with but it seems to be reliable. Not sure what the headers stored but they were basically used to compensate for the shortcomings in cheap custom chips from the 90s.

There are also maybe other possibilities for why 2 different ROMs might be detected as the same exact ROM, but I don't know what goodtools does.

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Thu Jan 17, 2013 12:22 am
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Post Re: Same ROM, different File?!
<pedantry>a header, as the name implies, is located at the beginning of the file.</pedantry>

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Thu Jan 17, 2013 12:56 am
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Post Re: Same ROM, different File?!
If you already have NSRT, you should look at what it can do.

Like remove overdumps, copier headers, and duplicate files.

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Thu Jan 17, 2013 1:56 am
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