I’ve been playing around with the concept of using the 2C02 PPU hum intentionally.
B00daW: So far I’ve created a flickering BG0 test ROM that yields no noise. I’ve also used NO CARRIER’s GlitchNES; then modified it so that the APU and all channels are turned on. All I get is a small pop when the APU turns on and a click when the NES is shut off.
Does anyone have any idea about which part of the PPU would be producing the hum and what would be done to purposefully make the hum? (Speaking strictly via software that is.)
Furthermore, what frequencies are achieved and are they consistent?
I’ll be messing about with this a bit furtherblargg: Haha, great idea. Hours later, here’s a demo that plays the first few notes of the SMB theme through the PPU. Run on a NES and plug your audio RCA cable into the VIDEO output to hear (turn down volume first, as the buzz is kind of loud).
ppu_tune.zip with NES ROM and ca65 source
I got side-tracked trying to play 6-bit PCM out of the PPU (couldn’t get the output levels to match what they should have). I did get 3-bit PCM working, but lack the RAM on my devcart to put any decent-length sample on it. Had to settle for a simple square wave. It just plays it by loading the palette with black and white, and toggling between the two entries by changing the PPU address (with rendering disabled). Connect NES normally to “see” the waveforms on screen.
|
|
||
|
TRACKLIST: b00DaW writes in with his new sequencer project: “The Fairchild Channel F (VES) was the first programmable ROM console geared toward  The Beast at rest. the consumer market. It was also originally designed with the ability to output three very out-of-tune tones on a single channel through its internal speaker. Sound obviously wasn’t a major priority; versus cost and playability. Saying this, people still generally had a good opinion of the games for the Fairchild Channel F. This was deemed the Channel F System II; which also failed in the US of A. However, Europe seemed to With a little bit of internet-aided archaeology, I was able to discover this console and also a pretty well-documented wiki focused on VES development. By disassembling and reverse-engineering the proprietary F8 assembly code for the game Pro Football, hackers were able to steal and optimize an effectively brilliant way to output all sorts of tones from the original three by essentially modulating one at different duty cycles. This is where my sequencer comes in. Currently, I am able to output a few octaves of notes with the little-modified Pro Football PlaySong routine. (I have other duty cycles and other effects in the making, but essentially am learning as I go.) Baron Knoxburry, Battle of the Bits father and brother, was able to create a very awesome tune using the first release of the sequencer. baron_knoxburry_-_fninja_channelf As you can see, the notes are in tune and even crude percussion is able to be Where is it now? The state of the sequencer:
So, what’s so cool about this single-channel sequencer for a 1976/1979 failed console? Well, you’re making it do something that it wasn’t originally designed to do for one. Also, this really helps in the aid of sound design. Every millisecond counts since you only have one channel to work with. It’s an intense challenge to produce quality music from a single channel, limited piece of hardware. This could practically aid in the design for new-age audio to any other chip you decide to “tune.” |
||
Comments