An A-SID trip, part 1

[stefano]

I've been playing with the C64 ever since I have memory. I probably even learnt to read and write on it. Yet I haven't asked myself how it generated sound until a few years ago, when I accidentally stumbled upon the MIDIbox SID. Since I do the work that I do, I looked around for information on the SID chip as well as on classic game music composers (such as the genius named Tim Follin) and modern chiptune music acts (YMCK are amazing). As I found out that:

• the SID chip contains a digitally-controlled resonant analog filter which can take analog audio as input;
• analog audio input and output are actually accessible through the A/V port on the back of the C64;
• people went as far as decapping the chip and taking die shots using light microscopes at micrometer resolution, and then reverse engineering the schematics from such pics;

I knew that one day or another I had to do something about it. And here we are now. Let me tell you about the long journey towards the creation of A-SID and its release on 2022-06-04. (should we call it C64 day now?)

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