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Comment by terlisimo | Hacker News Reader

> also the 6510 CPU and even some of the C64's CIA timers

yes, but also the VIC timers and the PLA. So basically you need all of the c64 chips emulated, at least in part :)

I wrote a simple SID player for fun and I feel like it's 20% shy of being a full c64 emulator, all it needs is video output and keyboard/joystick input.

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I have a physical SID chip and I was looking at implementations of players and ... was shocked at how complicated they are. I guess it makes sense though: SID files are tiny because they are in effect full C64 native programs that generate music. It would be hard to do otherwise on that platform.

I wrote a simple program that transformed basic (60hz, no PCM-style hacks) SID programs to like sequence of byte instructions for the SID chip so that I could replay without emulating and the file sizes are massive compared to the original!

Here is an awesome single file SID player written in C,

https://github.com/mlund/csid/blob/master/csid.c

Oh, wow! Such a compact cpu routine! Thanks for the link.

I wrote mine in C too and it's basically a 1k line switch statement for every 6510 instruction :) I went the extra mile and made it cycle-accurate though.

libsidplayfp is probably the best emulator out there. It actually emulates voltage levels at one stage. The wiki has a bunch of info on SID reverse engineered from die shots https://github.com/libsidplayfp/SID_schematics/wiki

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