Re: Playing samples on both new and old SIDs

From: Richard Atkinson (
Date: 2000-08-06 20:32:56

On Sun, 6 Aug 2000, Marko Mäkelä wrote:

> I've looked at the combined waveforms by sampling the OSC3 register every
> 16 or 32 cycles (I don't remember; anyway, I wrote the sampling loop so
> that crossing 256-byte boundaries made no difference in the sampling
> frequency).  At double waveform frequency, the output changes at double
> speed; there are no irregularities.  The cycles of the waveforms were 512
> bytes, unless I remember wrong.  This information is for the 6581; I
> haven't tested the new SID.

I've only ever had silence out of 6581s for the combined waveforms.
Perhaps they are quiet.

> So, there's no need to have a REU to measure the waveforms.

Yeah, but it's a helluva lot easier ;)

By the way, I have also coded cycle-exact timing routines for sound
applications; I wrote a subroutine to generate NES-style stepped
triangular waveforms on the volume register and it was as tight as
possible as well as accurrate on 256-byte boundaries. I had to specify its
location within a page so as to generate a 1 cycle penalty on certain
branch instructions.

Do you still have your program?


Richard Atkinson
Software Engineer
Tenison Technology EDA Ltd

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