5 ms·

Part of the problem with the SID particularly is its analogue components, such as the filter, which are very hard to simulate digitally. It's not just demos tha

Part of the problem with the SID particularly is its analogue components, such as the filter, which are very hard to simulate digitally. It's not just demos that depend on their behaviour. Even Commodore themselves weren't able to reproduce all of its subtleties (i.e., the 6581 vs 8580 differences). Bob Yannes did some amazing things with the chip, especially considering the limitations he had to work under: http://sid.kubarth.com/articles/interview_bob_yannes.html http://sid.kubarth.com/articles/interview_bob_yannes.html

tibbon 8y ago
I do wonder what it would take to emulate it more properly on a component level. It's definitely a "weird" filter and doesn't behave like one would assume it to.
- opencl 8y ago
  You could probably emulate the analog sections with a circuit simulator like SPICE.
  - 8bitsrule 8y ago
    Analog is hard to emulate well. At least, I've never heard of a decent emulation of the legendary Moog filter. 'Infinite' trumps 'many'
    - mrob 8y ago
      Analog is hard to emulate because real components have complicated non-linear and stateful behaviors, and because real circuits are full of parasitic components, not because of "infinite" anything. Analog circuits have finite SNR and bandwidth, and the "many" of digital can easily exceed them. Analog circuits also tend to have high variation between units. You might have a perfect simulation of the average hardware, but it won't necessarily sound like your specific hardware. You'll need to measure your hardware and tune the simulation to match. People have done this for SID chips: https://bel.fi/alankila/c64-sw/yourchip.html https://bel.fi/alankila/c64-sw/yourchip.html
      - deleted 8y ago
        [deleted]
      - 8bitsrule 8y ago
        In music 'high variation' is frequently a plus. For example the value of Stradivarius or Steinway (and countless other instrument brands) is dependent on 'hard to emulate'. Of course digital has its place ... but nature chose to go with analog.
- ZenPsycho 8y ago
  my understanding is that the first run had a hardware bug. i don’t totally understand it, but something about an impurity in the silicon creating circuit crosstalk that affected the filter in such a way as to accidentally create a lowpass filter—- or .. something, such that some games were able to do essentially PWM on first run SID chips, but not second run where the bug was fixed. reproducing this through emulation miiight be impossible.

tibbon 8y ago

I do wonder what it would take to emulate it more properly on a component level. It's definitely a "weird" filter and doesn't behave like one would assume it to.

opencl 8y ago
You could probably emulate the analog sections with a circuit simulator like SPICE.
- 8bitsrule 8y ago
  Analog is hard to emulate well. At least, I've never heard of a decent emulation of the legendary Moog filter. 'Infinite' trumps 'many'
  - mrob 8y ago
    Analog is hard to emulate because real components have complicated non-linear and stateful behaviors, and because real circuits are full of parasitic components, not because of "infinite" anything. Analog circuits have finite SNR and bandwidth, and the "many" of digital can easily exceed them. Analog circuits also tend to have high variation between units. You might have a perfect simulation of the average hardware, but it won't necessarily sound like your specific hardware. You'll need to measure your hardware and tune the simulation to match. People have done this for SID chips: https://bel.fi/alankila/c64-sw/yourchip.html https://bel.fi/alankila/c64-sw/yourchip.html
    - deleted 8y ago
      [deleted]
    - 8bitsrule 8y ago
      In music 'high variation' is frequently a plus. For example the value of Stradivarius or Steinway (and countless other instrument brands) is dependent on 'hard to emulate'. Of course digital has its place ... but nature chose to go with analog.
ZenPsycho 8y ago
my understanding is that the first run had a hardware bug. i don’t totally understand it, but something about an impurity in the silicon creating circuit crosstalk that affected the filter in such a way as to accidentally create a lowpass filter—- or .. something, such that some games were able to do essentially PWM on first run SID chips, but not second run where the bug was fixed. reproducing this through emulation miiight be impossible.