PET music (Was: hmm, don't remember what the thread was originally :)

From: Jim Battle <frustum_at_pacbell.net>
Date: Sat Jan 5 00:59:55 2002

At 03:03 PM 1/4/02 -0800, Ethan Dicks wrote:

>--- M H Stein <mhstein_at_usa.net> wrote:
> > Not sure what you're looking for here, hardware or software?
>
>Software. I can reconstruct the hardware I think.
>
> > Seems to me any S/W not using CB2 would require _some_ kind of special
> > hardware, however trivial.
>
>Yes. A connector, 8 resistors and a jack.

Nitpick alert --

Hmm, for your D/A converter to be monotonic, you biggest resistor needs to
be accurate to 1 part in 512*, or 0.20% tolerance, then the next one has to
be good to 1/256, the next good to 1/128, etc, otherwise the smallest one
isn't really doing much.

In reality, for this and other reasons, I'd expect you to only really get
6b or so of accuracy. It still beats silence, though.

*yes, 512, not 256, because you don't want to blow your entire error budget
on the first bit; so let the biggest one use up half the error margin, then
the next half of that, etc, such that the sum of each max error is equal to
your total error budget.

-----
Jim Battle == frustum_at_pacbell.net
Received on Sat Jan 05 2002 - 00:59:55 GMT