WIP: Port "Gameboy sound hardware" from the old wiki

gbdev / pandocs

The single, most comprehensive Game Boy technical reference.

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WIP: Port "Gameboy sound hardware" from the old wiki #562

Open remind-me-later opened 3 months ago

remind-me-later commented 3 months ago

Closes #552. Each section from the old wiki corresponds to a commit. I encountered the following issues while porting some sections:

The Channels section diagram is pretty ugly, I would like recommendations on how to redo it.
The Frame Sequencer section diagram has been skipped, since it doesn't match with SameBoy source, and I think that's more accurate.
The VIN mixing section is pretty bare and I don't know if the information in there is useful, so I skipped it.
The obscure behavior section could probably be refactored to be in Audio Registers, and Audio Details, but I don't know if that would make the rest of the section more bothersome to read.
I don't think a lot of version differences are mentioned in the rest of the page, so I skipped them as well.

avivace commented 2 months ago

@ISSOtm would you say we can start merging and afterwards "check" the statements ?

For "critical ones" we could directly add notes/earnings asking for help to verify the statements

ISSOtm commented 2 months ago

I don't know. The risk of adding false statements to Pan Docs always exists, and is a regression of sorts.

I'd like to fix them from the get-go if the resources (primarily motivation) are available, but if not, then yes we'll merge this and improve later.

remind-me-later commented 2 months ago

Thank you!

This looks largely like a straight port, correct? If so, I anticipate that we'll want to check some of the statements. Will you want to help with that?

Sure, for now I've been using SameBoy source as a reference but I don't know if there's a better source for checking the statements of the old wiki.

ISSOtm commented 2 months ago

SameBoy's source is one of the best references, since it's accurate, well-tested, and often well commented; but since it's code, it's still subject to interpretation. That's why we prefer citing test ROMs (when possible).

But “best effort“ remains in effect, so only verifying against SameBoy's source is perfectly fine, and hey, still miles better than just blindly copy-pasting some text! ^^

remind-me-later commented 2 months ago

Ok, I'll see if I can find some test ROMs, specially for the "obscure behavior" claims.

ISSOtm commented 2 months ago

Have you been able to find any test ROMs?

If not, that's fine, then SameBoy would be quite sufficient.

avivace commented 2 months ago

@remind-me-later do you have any update on this? It's fine to just mention SameBoy for the time being, we can open an issue for the test roms

remind-me-later commented 2 months ago

Have you been able to find any test ROMs?

If not, that's fine, then SameBoy would be quite sufficient.

I've seen that the blargg test roms check for some of the behavior of the sweep (cgb-sound tests 04-sweep and 05-sweep details) which seem to coincide with the behavior described. The test 03-trigger also matches the added text about triggering a channel. The parts I'm less sure of are some claims in the obscure behavior section, for example the zombie step paragraph, I've tried reading SameBoy's source about this but couldn't quite get how this mode works.