It's just weird then that they put a header originally defined by pirates, and now otherwise only used by third party emulators. Including matching the even more informal parts of the header byte for byte with the most common dump of the ROM on the high seas.

> ...a header originally defined by pirates...

Specifically, the "iNES header", originally created by Marat Fayzullin for use with his NES emulator, iNES[1].

If you look at the iNES manual[2], way down at the bottom in the changelog for version 0.7, you can see "Sound support completely rewritten, thanks to Kawase Tomohiro".

If you search the Internet for Kawase Tomohiro, you'll find[3] somebody by that name seems to work for Nintendo as a programmer, and in particular worked on the NES emulator used in 2001's Animal Crossing.

Of course, that's not conclusive evidence, but given the competing claims "Nintendo, a notoriously uptight company, has been downloading pirate ROMs to sell" versus "Nintendo hired a pioneer of NES emulation to work on their emulators, who kept using the tools and formats he was used to", I feel like one is more likely to be true and the other is more likely to get ad impressions.

[1]: https://fms.komkon.org/iNES/

[2]: https://fms.komkon.org/iNES/iNES.html

[3]: https://nintendo.fandom.com/wiki/Tomohiro_Kawase

It isn't wrong for Nintendo to use the same file format as other emulators, although it is hypocritical. (But including such improper stuff as "DiskDude" (which the emulator doesn't even use, and doesn't properly belong in the header anyways) is a bit wrong, and is even more hypocritical.)

I mean, you'd want to use a file format that would allow you to cross-test your emulator's behavior on the same ROM files against existing emulators' behavior on those ROM files. So you'd format your ROMs (which you dumped yourself) the way that existing emulators would expect them to be formatted.

Sorry, I was being a bit coy when I said the "more informal parts of the header". It literally still has the dumper's signature in the unused portion of the header. Traceability as to who gets props for the first good dump drives a lot of decisions in that scene.

Could you be more specific? I've heard this mentioned before but not seen an example. Something like one of those Diskdude! strings? What game?

http://wiki.nesdev.com/w/index.php/INES#Flags_10:

> Older versions of the iNES emulator ignored bytes 7-15, and several ROM management tools wrote messages in there. Commonly, these will be filled with "DiskDude!", which results in 64 being added to the mapper number.

That would surely be a giveaway, but I haven't seen any evidence that tagged headers like this were actually used in official Nintendo releases.

What other explanation would there be for those headers? They serve no purpose otherwise.

The other explanation is that they're using an open-source emulator (or some derivative thereof) in their product, so the iNES header would be the expected format to convey the necessary information.