[sdiy] trying to understand appregiators in late 70's synths

[Matthew Smith]

Quoth Dan Snazelle at 2009-01-04 08:29...
> i suppose the problem is made worse due to the face that without seeing what is PROGRAMMED on the CPU....well maybe this is a useless exercise.

One thing that will be programmed on the CPU would be the arpeggiator 
;-)  I suppose that it is possible to make an arpeggiator without the 
use of software but I certainly wouldn't want to try!

Writing the software for a hardware MIDI arpeggiator is a relatively 
trivial task.  You need to consider:

* Received notes on (and off).  I'd be inclined to ignore velocity as 
it's just something else to keep track of and I'd question its effect on 
an arpeggiated sequence.
* Polyphony - whether to ignore new notes when you exceed available 
polyphony or to work on a FIFO basis, dropping the oldest note. 
Probably a job for a ring buffer.
* Whether you are going to use just the notes received or whether to add 
  the same notes from higher/lower octaves.
* Duration of notes - you can derive this from the incoming MIDI clock 
where each clock message is 1/24th of a 1/4 note.

That's MIDI.  If your synth(s) has/have MIDI control, this could be a 
possible routing between your MIDI in and whatever you are using as an 
assigner.  If you're not using MIDI, maybe the principal can be adapted.

Cheers

M

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Matthew Smith
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