I made an Octave sc
ript to simulate and graph all the 2A03 sweep unit settings as they change pitch over time. It is based entirely on my understanding of some documentation I found online… no measurements have actually been done. Each staircase represents one iterated combination of bit shifting and clock dividing. Something about the various quantizations weaving in and out of each other is strangely hypnotic.
via Skrasoft
Lots of weekend news from skrasoft, developer of the 2a03 synth project. He writes
As has been well-documented all across the Internet, the NES 2A03 is not a sound chip. Though it contains all the Nintendo sound hardware, it is very much a processor that needs properly-formatted program data to run.
more “Sound Chip” Progress.
There are also posts about crude triangle volume control with audio, and another audio test. Project is looking good!
Via.
I put this together to tweak the 2A03 sound control system. It is essentially several processors and some buffering. Some parts are interconnected, and others are broken out into pin headers. It is powered by a standard 9-12V DC walwart, has two 1/4? output jacks (one for each set of channels), and includes MIDI input circuitry. It’s a little big at 6? by 6?, but the point is to make everything easily accessible by hand.
One of the features of the MIDI Pokey synth is the ability to have one MIDI channel control all the Pokey voices polyphonically. That allows it to play chords directly from a standard MIDI keyboard without any fancy processing in between. The Pokey has four voices, so it can play four note chords. It can also do three note chords plus a melody line, and any other permutation of four. Making it work was just a matter of deciding how to route multiple notes to multiple channels.
More info and audio on the Blog. I want this one pretty bad..
The first revision circuit board came back for the Pokey MIDI synth. It is up and running wonderfully. Audio examples are the same as in previous posts, and I’ll put more together as the MIDI engine expands. This was all on a series of breadboards before, so it is nice to have it condensed down to a single printed circuit board. It is 4? by 3?, with MIDI in, power in, and a 1/4? line out.
More info on the blog.
