C64 SID Phase Accumulator - Digital Sound Generation

Jeri explains the phase accumulators in the c64 SID sound chip. This technique was used in many early synthesizers and sound chips.

Category:

Music

Tags:

• Jeri Ellsworth
• SID
• 8bit Music
• sound
• c64
• synthesizer
• phase accumulator

[Textra1]

I did a couple of digi electronic units and a microprocessor fundamentals unit and I love this stuff. While I'm primarily a coder, understanding the digi concepts has helped me no end. Especially with the low-level coding.

Love your work Jeri.

5-stars

[jeriellsworth]

Thanks!  Glad you liked it. I love the SID and I plan on dissecting it more and sharing what I learned while making the C64 DTV

[frankbuss]

@ufo8mycat You'll find more information, if you search for Direct Digital Synthesizer (DDS). But the SID has some interesting tricks, like substituting the MSB of one accumulator with the MSB of another accumulator for ring modulation effects, or resetting one accumulator depending on the MSB of another accumulator for the synchronization effect.

[ufo8mycat]

I have virtually no comprehension of what you're talking about but I so desperately want to understand. Frustrating.

[SPFXsynthesisers]

There is just something incredibly sexy about a beautiful woman explaining digital electronics.

Great insite into this brilliant sound chip.

[epatto]

@FIXTREME No.

[sid6581]

So yeah, the "sampling rate" of the SID chip is really 1 MHz ! Bob Yannes did an amazing job with the SID ! The way the envelope (ADSR) works is pretty tricky ...

[stumpythumper]

From what I understand...some of the people who designed the C64 later created some nice Ensoniq synthesizers and samplers

[FIXTREME]

So with this information, you can convert an mp3 or wma audio file to a commodore 64 data?

[RobsElectroSoft]

delta phase = signal frequency / (sampling frequency * resolution phase accumulator)

[Intosia]

Wow very interesting!

[EricGus67]

Thanks for this video .. It's nice to know even after all this time the little C64 can still teach us something .. Looking forward to more videos.. Thanks for sharing your knowledge..