[sdiy] Analysis of the TB-303 CPU timing

[Colin f]

Hi Julian,

> Personally, I feel it would be cool to simulate the clock interplay to reproduce
> obseved experimental data and then explore the space in order to get it
> more tight or more loose. Would it have a big impact on sound and
> experience? Would people care or notice if they used a much tighter 303
> clock wise?
> While I'm at it and have all the hardware here I could set up some A/B testing
> audio files. Do you think it would be worth the hassle?

You can clearly demonstrate the effect of the clock interplay on a real 303, but not in the sort of circumstances you would actually use it.
The tempo clock input is clearly polled by the interrupt routine. It the interrupt period is set too long, it misses clock pulses.
If you really want to know what goes on in the 303 CPU, the original mask ROM seems to have been extracted, and there is code from the MAME base to emulate the CPU.

Cheers,
Colin f