nesdev.org

This is a good example of how low-pass it would get: https://www.youtube.com/watch?v=gyS5ymEURJw

Misinterpreted documentation would make sense, there are similar cases for the APU, like in Ikari Warriors II, which plays RAW via $4011 but still sets up and starts the DPCM unit like during normal 1-bit delta playback. Or take some Capcom games that write $30 to $400C and then also a $07 to $4015,...

If I end up having enough space at the end of development, I do plan on adding a randomized "Endless mode" (á la Megaman 9 and 10) to my game, and it pretty much requires no RAM at all. But that's because the entire thing runs on a timer that spawns sets of enemies from data in ROM, all I ...

I've always wanted to know if it was possible to use the 5 FM-only channels of the YM2612 chip to output PCM. For most chips this works by setting the channel in question to the highest possible frequency, and then the attenuation/volume register can serve as the output for the data. I wonder if thi...

I've tested the effect of the OAM DMA distortion with my FME-7 test ROM before. This exemplifies the worst possible distortion though where the output is delayed, since the sample is fetched from ROM inside the IRQ handler. But this could be solved as well by manually adjusting the vector after each...

My method probably has the highest sample rate possible without mapper IRQs. Depending on what you're going for, it can even do music fairly decently, but your best bet is to play something more orchestral: (This is without OAM DMAs) https://www.youtube.com/watch?v=mddZUUcu_fU I would be happy to he...

I've recently found that passing arguments can prove to be somewhat troublesome depending on what you have in mind. Obviously, one might go for a route where each CPU register holds one of the arguments assuming there are up to 3 arguments. Some situations might call for a method that only uses 'A' ...

Sometimes I wonder if anyone else feels like that when finding a solution to a certain problem during development (be it NES or otherwise). Like this instance where I had a bunch of things to comment out, but no "block comments" in ASM6: .if 1 = 0 .db 0,3,6,9,12,16,19,22 .db 25,28,31,34,37...

14 914 CPU cycles 14 914 APU cycles. I did mean CPU cycles. Since the write immediately decrements the length counter of the channel in question, only 2 frame counter steps out of the 5 have to occur before the length counter gets clocked again, which amounts to 7456.5 APU cycles. I'm not exactly s...

Here's an idea that may or may not be useful, but I thought it would be worth sharing here. So the frame counter allows for clocking the length counters at a ~96Hz rate with the 5-step mode selected, and writing to $4017 clocks all the hardware timer units. By writing $18 to $400F and then $C0 to $4...

The effect of BIT is probably why I use it the most. The way I handle the math doesn't really need the V flag because most of the time I add signed 16-bit values to unsigned 16-bit values... so I still only ever need the carry for that (though I have to interpret the carry differently based on the s...

I've always tried to address this from both directions: My engines can either have a length counter-like timer in software to stop the sound, or a "stop the sound when less than X frames of duration are left for this note". It makes things as opened up as I need them to be.

In a game (provided that the sampling rate is not too high), any N163 channel could be easily used to play 4-bit PCM data with volume control by having the channel set to a 4-step wavetable, with all steps of that wavetable always being equal. To avoid potential noise coming from the little time del...

I've had this crazy idea of "could an NES game cartridge be removable without the game crashing?". I realize the space issue would be huge, since there would only be a bit above 1.5k of code that could be housed by the RAM, while still leaving some zero page and stack space for variables. ...

Great job, especially because now we can listen to the samples without any NMI or OAM DMA cutting into the sound like in-game.