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Extend VRC6 audio into Mapper 30

Posted: Mon Nov 11, 2019 3:05 am
by bluefoxicy
If I understand Mapper 30 right, it has a large amount of unused mapped space. According to [url=https://wiki.nesdev.com/w/index.php/CPU_memory_map]NESDev[/url], PRG RAM, PRG ROM, and mapper registers start at $4020 and continue to $FFFF.

Can we extend VRC6 audio into Mapper 30 by simply putting the VRC6 audio registers at $4044-$4053? (I'm working on a 128MB PRG RAM FPGA-based mapper that costs around $11 of circuitry and part of its register bank is VRC6 audio, hence the funny address.)

Re: Extend VRC6 audio into Mapper 30

Posted: Mon Nov 11, 2019 10:23 am
by Mugi
no, you can't put VRC6 into a mapper 30 board.
VRC6 is a hardware chip, which is not present on a mapper 30 board. If it was, it wouldn't be a mapper 30 board, it would be a VRC6 board.

Re: Extend VRC6 audio into Mapper 30

Posted: Mon Nov 11, 2019 12:12 pm
by bluefoxicy
I'm asking if Mapper 30 can be specified with an extension to map the VRC6 audio registers (not the whole VRC6 mapper) at a particular address, such that a new revision of the mapper chip can incorporate VRC6 audio output (potentially on expansion pin 6, which is commonly wired to audio out by an expansion port adapter).

AFAIK there's nothing at $4044-$4053 on Mapper 30, so writing there is harmless on revisions without this capability.

Re: Extend VRC6 audio into Mapper 30

Posted: Mon Nov 11, 2019 1:27 pm
by Mugi
well for making modifications to the mapper itself, you might want to approach people who develop the mappers instead, such as INL who makes the mapper 30 boards nesmaker uses.

Re: Extend VRC6 audio into Mapper 30

Posted: Tue Nov 12, 2019 1:44 am
by bluefoxicy
Good point. I'll check with them.