Custom Synthesizer Adventures with the 6581 SID (Patreon)

How've you been doing? I've been quiet (sorry about the lack of posts), but busy. I'm preparing a sort of mega-update; I'd like to post an update every day or two with everything that's been going on, if possible. With travel coming up, I'm certain I'll have some free time... Oh! Speaking of which, I'll be up in Boston for @party in a little over a week, and I would love to see you there! Come out, hang out, support the US demoscene, and let's watch some spinning cubes kick ass. (I'll also be giving a presentation)

Anyway, let's talk about that video you see up top. It's only a minute long, but what a glorious minute it is!

You see, it's been at least a few months since I've talked about the synthesizer, though I did get to show it off at VCF East, which was a lot of fun. The progress has been slow for a variety of reasons, one of them being jobs have popped up here and there, but to jog your memory, we last left the synthesizer adventure with some hangups:

• The boards all booted, but only one board worked.
• Even then, only one board could be plugged in at once without hax.
• Even then, only one board could be used at once without hax.

There's actually a hint in how I solved the middle issue in my first synthesizer post, but the problem was that the driver would have to be hardcoded to a specific vendor:device ID, and it would only talk to that board. And furthermore, one of each type of board was all I'd get, so no dual-POKEY / dual-SID type setups. I am interested in something more flexible than this, so after a bit of conversation with Charles (who this would not even be possible without) we coded up some new functions that would search for all boards connected with a specific vendor ID, and then hold onto the device ID string so you can see which boards are plugged in, in which order, and send commands to specific boards.

With the new code, I should be able to support hotplug/unplug in my tracker without crashes (famous last words) and even implement A/B board testing so I can hear differences between two different boards with the same chip. 

Another thing that has been worked on is the I/O glue logic, which is to say, the part that shuffles all of the data I send to the board over to the sound chip itself. Even though this code was written and in theory worked out of the box, I never had a proof-of-concept keyboard + driver to diddle the SID's bits, only the POKEY. And I wasn't quite sure everything was right with my SID, either. Even once I got it working, it was not very stable.

I sat down about 30 hours ago with a goal of making the SID board happy before leaving to travel north. I'm happy to say I cleaned up some wiring, discovered a few mistakes, and generally overhauled everything I did. So here we are! You (and my youtube subscribers, but don't worry, my stats seem to think none of them have woken up yet) are the first to see the SID board beep with all the kinks worked out.

The video does not display multiple voice control which works fine nor that both POKEY and SID can coexist and notes can sound from both simultaneously. Sometime soon I'll get a video up of that for you. For now, I'm going to get my tracker supporting the boards better, and maybe I can write something for POKEY+SID.

Any requests? =]