The C64 then reads the frequency the 555s are oscillating at, and then converts these into pitch and volume data to be fed to the SID audio chip. [Linus Åkesson] demonstrates the build ably by ...

The VIC-II, the video chip for the C64, had sprites and scrolling, all stuffed into a single bit of silicon. The SID chip was a complete synthesizer on a chip. These bits of silicon made the C64 ...