Subj : Old Geek Thoughts...
To   : McDoob
From : TALIADON
Date : Fri Jan 07 2022 11:15:55

 Mc> That's a problem for C64, from what I've heard...I think the SID chip
 Mc> hasn't been reverse-engineered...

TBH, even commodore had difficulty in maintaining the analogue nuances (filter
response in particular) between the 6581 & 8580 revisions. Like all analogue
designs; layout, substrate, masking, lithography, and manufacture, are all
components of signal fidelity & frequency response. With the 6581 in
particular, Bob Yannes decided to employ rather than mitigate these nuances;
as the silicon/process nuances changed, so did the signal. If you isolate
and play the 6581 & 8580 side-by-side, the differences are certainly
perceptible to the human ear.

Unlike most analogue engineers, Bob didn't seem too concerned about marginal
parasitics: why add more silicon when you can simply add more 'features'.
This unique (and rather clever IMHO) approach gave the original SID a very
unique timbre that's difficult to reproduce in its entirety.

As far as re-engineering goes, I think the SwinSID is as good as it gets, at
least for now.

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