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Repose
Registered: Oct 2010
Posts: 222 |
Ultimate reverse engineering
This person took 32 chips of every revision, connected them to a custom clock source and ran them independently, to read out the OSC3/ENV3 of every combination, plus analog recordings. He wrote an emulator which recreates every register setting and measures all the variations within and between chips. Its an amazing amount of work. He also reverse engineered CIA's as well, as those are needed for "real sid" type tunes, which require emulating the entire machine for music playback.
https://www.youtube.com/watch?v=pePq68HaI7M
Emulating the SID the HARD way.
plgDavid
Here is one of the "torture test" tunes which require very accurate emulation of a specific model, it sounds amazing:
https://www.youtube.com/watch?v=BVevORuyQ_8
Jammer - Club Stylier
Club Stylier
Forever 2010 - #1 |
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iAN CooG
Registered: May 2002
Posts: 3138 |
true dedication, very interesting |
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chatGPZ
Registered: Dec 2001
Posts: 11148 |
I wonder why you link to a video that plays the tune in a 10 year old VICE though :) I don't expect 8580 Tunes to benefit much from this research either - it's mostly relevant for the 6581 Filter distortion and the mixed Waveforms perhaps. We'll see when he posts the testrig :) |
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Repose
Registered: Oct 2010
Posts: 222 |
I agree it's not the best link, but its the one I could find. Please link a better if you find it :)
There are other videos where he plays some demos, and its true that he said the variations in the 6581 model of the SID are more dramatic. But, he did mention some tricky problems in ADSR bugs and combined waveforms and PCM techniques. |
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chatGPZ
Registered: Dec 2001
Posts: 11148 |
Yeah, most of it is old news though - he replicated a lot of what Alankila already did years ago - whats new is that he used analog recordings to get full 12 bit resolution for the combined waveforms.... however, given their totally unpredictable nature and variation on real chips, i really doubt it makes and audible difference :)
As said, we'll see when it's all posted - then we can run his stuff against reSID and fix it eventually :) |
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Repose
Registered: Oct 2010
Posts: 222 |
Not sure if you noticed, but it is posted here: https://plogue.com/products/chipsynth-c64.html |
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Repose
Registered: Oct 2010
Posts: 222 |
I've found the differences explained in the manual at https://s3.amazonaws.com/chipsynth/C64_manual.pdf
2092 Slightly more
resonant.
2792 Good average
8580.
4887 Has mellower
combined
waves. |
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acrouzet
Registered: May 2020
Posts: 80 |
There's some stuff emulated here that isn't in ReSID, such as oscillator leakage and the variation in combined waveforms between chips. Apparently the elusive R1 is emulated too. ReSID's 6581 filter also has a few bugs, so I'm wondering if this emulation is an improvement overall. |
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Repose
Registered: Oct 2010
Posts: 222 |
Here may be a better link to one of the test tunes that I mentioned.
https://deepsid.chordian.net/?file=/MUSICIANS/J/Jammer/Club_Sty.. |
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iAN CooG
Registered: May 2002
Posts: 3138 |
Quote: Here may be a better link to one of the test tunes that I mentioned.
https://deepsid.chordian.net/?file=/MUSICIANS/J/Jammer/Club_Sty..
You're just linking a site that emulates in the browser the sid tune contained in HVSC. Anyone is able to play a sid tune by himself with an emulator, which are knowingly "not exact".
A sound capture from an emulator has no example value exactly as one emitted directly by the emulator. We already know they're not sounding like the real thing, if we exclude 8580 chips which are more "digitally correct" than the mostly unpredictable 6581s.
What really counts as an example is an actual sound capture from a real C64 with a real SID chip. |
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Repose
Registered: Oct 2010
Posts: 222 |
I agree with you, however the complaint was that my first link was to a 10 year old copy of VICE, and the next link was improved by being a recent emulator.
I did say "may be better" :)
I still haven't found an authentic recording of this tune. |
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