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Keyboard is pretty amazing for C64 preservation efforts. Perhaps lessons learned could be applied to other same era systems. There's one part in C64 that's bec

Keyboard is pretty amazing for C64 preservation efforts. Perhaps lessons learned could be applied to other same era systems. There's one part in C64 that's becoming more and more rare — the amazing SID sound chip. I wonder whether it'd be possible to have production runs of truly new 6581 and/or 8580 SID chips. Does someone still have the old masks? Other chips you could emulate with an FPGA. But SID is partially analog, so it's special. Some say no two SIDs sound the same. Btw, recent C64 music demo playing off 1 MB Ocean style (= ROM) cartridge (not REU): https://www.youtube.com/watch?v=7qxxnJVU4jQ https://www.youtube.com/watch?v=7qxxnJVU4jQ https://www.youtube.com/watch?v=UYAf_awh5XA https://www.youtube.com/watch?v=UYAf_awh5XA Yes, it's real. Not particularly good example of SID though, but still impressive for 1982/83 technology. But this one does show off SID; C64 "Cubase", realtime DSP (timestretch, low/high pass filter, distortion, etc.) pretty amazing: https://www.youtube.com/watch?v=k4GWheE4Gkw https://www.youtube.com/watch?v=k4GWheE4Gkw

monocasa 9y ago
> Does someone still have the old masks? You can probably reverse the masks with a microscope with a little elbow grease. Not trivial by any means, but doable by someone in a garage as a hobby. The real question, does a fab that can work with that process still exist?
- jdswain 9y ago
  There’s an ongoing effort to understand the SID here http://forum.6502.org/viewtopic.php?f=8&t=4150 http://forum.6502.org/viewtopic.php?f=8&t=4150 Lots of interesting analog chip level stuff, it’s all new to me as I’ve only dealt with things at the digital level, but very interesting to see how the fabrication technology works in an analog way..
JKCalhoun 9y ago
Not an EE, but might an FPGA be created to mimic one?
- jammi 9y ago
  No, not for that. Its sound characteristics are from the physical layout of the chip and the individual differences from manufacturing is more notable on old revisions of 6581 than newer ones. 8580 models sound more or less identical to each other thanks to the improved manufacturing technology.
zaxomi 9y ago
Well, while the sound is coming from the SID-chip, it actually is samples. The really impressive thing is that they can play samples even tough the SID-chip was not designed to play samples. The author of "Cubase64" (Pex "Mahoney" Tufvesson) has written an interesting explanation of how it is made: https://livet.se/mahoney/c64-files/Cubase64_White_Paper_by_Pex_Mahoney_Tufvesson.pdf https://livet.se/mahoney/c64-files/Cubase64_White_Paper_by_P... The technique used in the two first links of parent comment, is, as I understand it, based on another work of Pex : https://livet.se/mahoney/c64-files/Musik_RunStop_Technical_Details_by_Pex_Mahoney_Tufvesson_v2.pdf https://livet.se/mahoney/c64-files/Musik_RunStop_Technical_D...
jammi 9y ago
None of those digitized things really are what the SID is about though, nor do they show it off for what it really is; a synthesizer for playing 3-channel tunes like these: https://www.youtube.com/watch?v=2wbwKdV89pE https://www.youtube.com/watch?v=2wbwKdV89pE For digitized sound, the SID isn't different from something like a PC beeper.
- vardump 9y ago
  > None of those digitized things really are what the SID is about though Fair enough. Although cubase64 does use SID features in an innovate way. > For digitized sound, the SID isn't different from something like a PC beeper. C64 is way superior for playing samples compared to PC beeper. Only commonality is that it takes high amount of CPU cycles, in the linked example all of it.
  - jammi 9y ago
    A PC beeper can sound just as good, when used on a fast enough PC and the beeper output is connected to something better than the built-in piezo speaker. Even on the original IBM PC, you could make it sound almost as good by very careful optimization and close to 100% of allocation of CPU cycles, like shown at the end of the 8088 MPH demo: https://youtu.be/hNRO7lno_DM?t=6m52s https://youtu.be/hNRO7lno_DM?t=6m52s
    - vardump 9y ago
      We can agree to disagree, I just don't think PC beeper can in any realistic circumstances sound as good as this: https://www.youtube.com/watch?v=U7PF5DSpjgM https://www.youtube.com/watch?v=U7PF5DSpjgM
      - jammi 9y ago
        How about this? There are also plenty of DOS PC-speaker-savvy demos from the 90s on pouet.net and scene.org, but there are apparently no recordings of them on youtube without sound card configurations. Some of the late DOS games also had awesome PC-speaker support. There was also a Windows sound driver for the PC speaker in Windows 3.1 times, maybe Windows 95 as well. Basically; the faster the PC, the higher the sampling rate you can go. The sound output on Raspberry Pis and some of the cheaper USB sound cards are also very similar to having stereo PC speakers, since that's also about just dumb bit-banged PWM. https://www.youtube.com/watch?v=dV1EMcH316s https://www.youtube.com/watch?v=dV1EMcH316s

monocasa 9y ago

> Does someone still have the old masks? You can probably reverse the masks with a microscope with a little elbow grease. Not trivial by any means, but doable by someone in a garage as a hobby. The real question, does a fab that can work with that process still exist?

jdswain 9y ago
There’s an ongoing effort to understand the SID here http://forum.6502.org/viewtopic.php?f=8&t=4150 http://forum.6502.org/viewtopic.php?f=8&t=4150 Lots of interesting analog chip level stuff, it’s all new to me as I’ve only dealt with things at the digital level, but very interesting to see how the fabrication technology works in an analog way..

JKCalhoun 9y ago

Not an EE, but might an FPGA be created to mimic one?

jammi 9y ago
No, not for that. Its sound characteristics are from the physical layout of the chip and the individual differences from manufacturing is more notable on old revisions of 6581 than newer ones. 8580 models sound more or less identical to each other thanks to the improved manufacturing technology.

zaxomi 9y ago

Well, while the sound is coming from the SID-chip, it actually is samples. The really impressive thing is that they can play samples even tough the SID-chip was not designed to play samples. The author of "Cubase64" (Pex "Mahoney" Tufvesson) has written an interesting explanation of how it is made: https://livet.se/mahoney/c64-files/Cubase64_White_Paper_by_Pex_Mahoney_Tufvesson.pdf https://livet.se/mahoney/c64-files/Cubase64_White_Paper_by_P... The technique used in the two first links of parent comment, is, as I understand it, based on another work of Pex : https://livet.se/mahoney/c64-files/Musik_RunStop_Technical_Details_by_Pex_Mahoney_Tufvesson_v2.pdf https://livet.se/mahoney/c64-files/Musik_RunStop_Technical_D...

jammi 9y ago

None of those digitized things really are what the SID is about though, nor do they show it off for what it really is; a synthesizer for playing 3-channel tunes like these: https://www.youtube.com/watch?v=2wbwKdV89pE https://www.youtube.com/watch?v=2wbwKdV89pE For digitized sound, the SID isn't different from something like a PC beeper.

vardump 9y ago
> None of those digitized things really are what the SID is about though Fair enough. Although cubase64 does use SID features in an innovate way. > For digitized sound, the SID isn't different from something like a PC beeper. C64 is way superior for playing samples compared to PC beeper. Only commonality is that it takes high amount of CPU cycles, in the linked example all of it.
- jammi 9y ago
  A PC beeper can sound just as good, when used on a fast enough PC and the beeper output is connected to something better than the built-in piezo speaker. Even on the original IBM PC, you could make it sound almost as good by very careful optimization and close to 100% of allocation of CPU cycles, like shown at the end of the 8088 MPH demo: https://youtu.be/hNRO7lno_DM?t=6m52s https://youtu.be/hNRO7lno_DM?t=6m52s
  - vardump 9y ago
    We can agree to disagree, I just don't think PC beeper can in any realistic circumstances sound as good as this: https://www.youtube.com/watch?v=U7PF5DSpjgM https://www.youtube.com/watch?v=U7PF5DSpjgM
    - jammi 9y ago
      How about this? There are also plenty of DOS PC-speaker-savvy demos from the 90s on pouet.net and scene.org, but there are apparently no recordings of them on youtube without sound card configurations. Some of the late DOS games also had awesome PC-speaker support. There was also a Windows sound driver for the PC speaker in Windows 3.1 times, maybe Windows 95 as well. Basically; the faster the PC, the higher the sampling rate you can go. The sound output on Raspberry Pis and some of the cheaper USB sound cards are also very similar to having stereo PC speakers, since that's also about just dumb bit-banged PWM. https://www.youtube.com/watch?v=dV1EMcH316s https://www.youtube.com/watch?v=dV1EMcH316s