The coolest thing about the SID chip (it was also in the
VIC20), at least to me, was that it had a
white noise generator. And you could read the wave level of the white noise generator.
The interaction of the white noise generator with the timing of the reads probably made the system complex past
uncertainty. This made it possible to generate
true random numbers.
It's fun to think that, at least. Please don't burst my bubble.