Re: PET user port programming

The wayback machine archived it over the years.

https://web.archive.org/web/*/http://petsynth.org/

On May 10, 2017 10:02 AM, "Mike Stein" <mhs.stein@gmail.com> wrote:

> Looks like he's let the site expire; any other links to PetSynth anywhere?
>
> m
>
> ----- Original Message -----
> From: "Leif Bloomquist" <leif@schemafactor.com>
> To: <cbm-hackers@musoftware.de>
> Sent: Wednesday, May 10, 2017 9:01 AM
> Subject: Re: PET user port programming
>
>
> MIDI on the PET, cool!
>
> You should check out PetSynth, I believe the source code is available:
>
> https://en.wikipedia.org/wiki/PetSynth
> http://www.petsynth.org/
>
> While it's a player not a sequencer, it also uses an Arduino on the
> user port and creative use of timers from what I recall.  Anyway,
> worth looking at.
>
>
> (I'd love to see a PET duet, your sequencer code on PET #1 and
> PetSynth on PET #2)  ;-)
>
> Cheers,
> -Leif
>
>
>
>
>
> --
> Leif Bloomquist | leif@schemafactor.com | +1 416-737-2328 | Check out
> my blog! http://www.jammingsignal.com
>
> "Every choice, no matter how small, begins a new story." - xkcd
>
>
> On Wed, May 10, 2017 at 6:25 AM, Chris Wareham <chris@chriswareham.net>
> wrote:
> > Hi,
> >
> > I've just signed up to the list as I'm currently writing a simple MIDI
> sequencer for my PET 4032. I'm using the cc65 compiler suite, but having
> difficulties finding information on user port programming and timing.
> >
> > At the moment I have a home made circuit on a breadboard with an LED for
> each of the data pins on the user port. When I write a byte to the data
> register for port A the corresponding LEDs light up. The missing pieces of
> the jigsaw are how to do the timing so that bytes get written at the
> correct intervals and the handshaking so I know when each byte has been
> read. I'm guessing I do the timing by setting a timer and handling
> interrupts, but neither of my two PET programming books cover this.
> >
> > MIDI messages consist of three bytes, but I've got my pseudo MIDI
> messages down to two bytes:
> >
> > mnnnnnnn ccccvvvv
> >
> > Where:
> >
> > m is 1 for note on or 0 for note off
> > nnnnnnn is the note number 0-127
> > cccc is channel 0-15
> > vvvv is velocity 0-15
> >
> > MIDI supports velocity values of 0-127, so I plan on shifting my 4 bit
> value to get a reasonable spread of velocities. I plan on using an Arduino
> to convert my pseudo MIDI messages into real ones. Hopefully I can then
> make an interface with a suitably programmed Atmega chip rather than a
> complete Arduino board.
> >
> > Any advice will be most gratefully appreciated!
> >
> > Regards,
> >
> > Chris
> >
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>
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>
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