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by rainwarrior
Thu May 13, 2021 3:43 pm
Forum: NESdev
Topic: MMC3 with CHR-RAM on specific device.
Replies: 11
Views: 510

Re: MMC3 with CHR-RAM on specific device.

Another thought: change one byte in the Mega Man 4 ROM and see if it still runs? Might want to rule out that the emulator is relying on a database of CRCs to select the cart function. Any recommendation for a specific program that works on mac for patching it out? You could just open it with a hex ...
by rainwarrior
Wed May 12, 2021 12:07 pm
Forum: NESdev
Topic: MMC3 with CHR-RAM on specific device.
Replies: 11
Views: 510

Re: MMC3 with CHR-RAM on specific device.

Another thought: change one byte in the Mega Man 4 ROM and see if it still runs? Might want to rule out that the emulator is relying on a database of CRCs to select the cart function.
by rainwarrior
Tue May 11, 2021 1:00 pm
Forum: NESdev
Topic: MMC3 with CHR-RAM on specific device.
Replies: 11
Views: 510

Re: MMC3 with CHR-RAM on specific device.

lidnariq wrote:
Tue May 11, 2021 11:00 am
Maybe the emulator incorrectly uses the PRG RAM protection bits for CHR RAM also??
Mega Man 4 doesn't ever write $A001 (or its mirrors) as far as I can tell.

Though it might be worth having a "sta $A001" after the "sta $A000" in the initMMC3 code there, just to be sure to initialize that.
by rainwarrior
Mon May 10, 2021 6:34 pm
Forum: NESdev
Topic: MMC3 with CHR-RAM on specific device.
Replies: 11
Views: 510

Re: MMC3 with CHR-RAM on specific device.

There is code to initialize, and debugging the artifact build for that branch this code does run. Unless the test was done with a different ROM (e.g. the master branch build?) I don't think MMC3 initialization is the issue here? .segment "STARTUP" ; startup values for the 8 MMC3 registers mmc3_regis...
by rainwarrior
Fri May 07, 2021 7:54 pm
Forum: NESdev
Topic: PPU warmup is real
Replies: 18
Views: 17893

Re: PPU warmup is real

I'm wondering if this is why Alfredo and Jigsaw (from Action 52) won't boot except on certain emulators (from what I understand those games don't run on the actual cartridge version either) No, the Action 52 startup menu already waits for the PPU to warm up long before you'd be able to select eithe...
by rainwarrior
Thu May 06, 2021 3:29 pm
Forum: General Stuff
Topic: C optimizations?
Replies: 2
Views: 387

Re: C optimizations?

That code is very simple and direct. I'd expect a modern compiler to do a very good job optimizing that, especially if it allows SSE2 optimizations. (Even more if you want to allow AVX.) However in the general question "can this be optimized", I don't think that can be answered without looking at th...
by rainwarrior
Wed May 05, 2021 1:46 pm
Forum: NES Music
Topic: What's the most common way to implement vibrato?
Replies: 16
Views: 1443

Re: What's the most common way to implement vibrato?

I'll admit that kind of went over my head. :? Pick a depth. Go down that many rows in the table. Pick a speed, go through the row left to right at that speed. Those are your pitch offsets. If you're using vibrato speed 1, step 1 column at a time. If using speed 2, step 2 columns, etc... After going...
by rainwarrior
Wed May 05, 2021 12:39 pm
Forum: NES Music
Topic: What's the most common way to implement vibrato?
Replies: 16
Views: 1443

Re: What's the most common way to implement vibrato?

I was hoping there would be a chart somewhere ; Vibrato table (256 bytes) ft_vibrato_table: .byte $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00, $00 .byte $00, $00, $00, $00, $00, $00, $01, $01, $01, $01, $01, $01, $01, $01, $01, $01 .byte $00, $00, $00, $00, $01, $01, $...
by rainwarrior
Sat May 01, 2021 1:44 pm
Forum: NES Music
Topic: What's the most common way to implement vibrato?
Replies: 16
Views: 1443

Re: What's the most common way to implement vibrato?

What's the most common way to implement vibrato for an nes music engine? Specifically for the pulse channels. I'm using Famitracker. I tried using APU Sweep, but cant get it quiet right. At the engine level, Famitracker makes use of the sweep as part of its vibrato, but in an obtuse way (a way to a...
by rainwarrior
Fri Apr 30, 2021 3:43 pm
Forum: General Stuff
Topic: Zelda II - The Adventure of Link... SUCKED
Replies: 28
Views: 2713

Re: Zelda II - The Adventure of Link... SUCKED

Pokun wrote:
Fri Apr 30, 2021 2:51 pm
Yes and that isn't so strange if you consider that it wasn't even a Zelda game early on in the development.
What was it?
by rainwarrior
Mon Apr 26, 2021 1:06 pm
Forum: NES Hardware and Flash Equipment
Topic: VRC6b conversion to VRC6a - Madara to Akumajo Densetsu question.
Replies: 12
Views: 1412

Re: VRC6b conversion to VRC6a - Madara to Akumajo Densetsu question.

The way I did it is fully reversible. I just vacuumed out the old solder and bent the pins up through and straightened them out. Then I ran small kynar wire up through the old vias to each new pin. You can't even really see the wires from the top. It can be potentially risky doing it that way thoug...
by rainwarrior
Mon Apr 26, 2021 1:01 pm
Forum: Newbie Help Center
Topic: Can i use BIT $2007 to increment the PPU pointer and not write anything?
Replies: 5
Views: 801

Re: Can i use BIT $2007 to increment the PPU pointer and not write anything?

Yes, that can be used.

However, if using DPCM it should not, because there's a possibility of a double-read conflict if the sample is fetched at the same time, which will increment twice.
by rainwarrior
Sun Apr 25, 2021 3:44 pm
Forum: NES Hardware and Flash Equipment
Topic: VRC6b conversion to VRC6a - Madara to Akumajo Densetsu question.
Replies: 12
Views: 1412

Re: VRC6b conversion to VRC6a - Madara to Akumajo Densetsu question.

Danexmurder wrote:
Sun Apr 25, 2021 12:19 pm
It seems like all I would need to do would be to lift pins 9 and 10 and switch them.
If you can follow the traces on the board, it might be easier and less damaging to the chip to cut the traces with a knife and reconnect the pins with wires instead of cutting/lifting them.
by rainwarrior
Sun Apr 25, 2021 12:00 pm
Forum: Newbie Help Center
Topic: Conversion chart for APU writes to notes?
Replies: 14
Views: 2184

Re: Conversion chart for APU writes to notes?

It's a shame the pitch takes up 11 bits instead of 8, those extra 3 bits make the file size twice as large don't they? The pitch table is only ~150 bytes. Though, you could make it even smaller by only storing one octave and shifting it with rounding compensation... but the result would be slightly...