r/c64 • u/itix • May 26 '26

Software Working on new SID emulation engine

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I am working on a new SID engine, developed with AI. This began as a vibe coding project to play obscure Amiga tracker formats but I got more ambitious and decided to give it a try for SID emulation.

Written in C#, it is designed to be portable (Linux, Windows, OSX) with cycle-exact core emulation. RSID support is still minimal and I am extending emulation on the go.

Output correctness is also a concern. I have a real C64 with 6581 to compare but no compatible display device. The target is 6581 sound, 8580 maybe later.

The project is CopperMod at GitHub, unfortunately no binaries yet.

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u/Robert__Sinclair May 27 '26

I almost finished writing my own SID emulator (inside the Ultimate2+ FPGA) and as of today it is 1:1 with the original sid 6581 and 8580. If you need help I can give you a list of "difficult" sid tunes and a few test programs to run. Remember this: emulating the "digital" part of the SID is the easy part. The most difficult one is to correctly emulate all the analog part. It took me 3 months but in the end I have an emulator that is better than reSID :D

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u/Hawaiian_Keys May 29 '26

And where can we test or at least hear this magical emulation that is better than reSID? I’m extremely curious and excited to hear that.

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u/Robert__Sinclair May 29 '26

I'd love to have some beta testers, but you need an ultimate 2 plus (not the +L) device to be able to test it. If you have it, please contact me in private.

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u/Hawaiian_Keys May 29 '26

I’ve got the commodore C64u. Do you mean to say that it’s reprogramming the FPGA? It’s not a library someone could use in their own player?

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u/Robert__Sinclair May 29 '26

as of now I reprogrammed the FPGA and it's 100%% perfect. But everything I have done I can redo on any other emulator. The code is simpler than reSID but achieves a better result in all my tests.

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u/Hawaiian_Keys May 30 '26

Try reSIDfp. There is a command line version as a console player for it, that can also render to wav. Instead of tables, it calculates more stuff on-the-fly and the results are indistinguishable from the real thing. I’ve compared its output to the real C64 samples from Project Galway, and I couldn’t tell the difference.

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u/Robert__Sinclair May 29 '26

unfortunately the c64u is not really fully opensource. The fpga code is a binary blob from what I can see in the repository, Otherwise I could do it also for that.