Analogue-sequencer

Chiel asked:

> >i have just one question to which i think i already know the answer 
> >but i'm finding it kinda hard to believe; are all the playlist- and 
> >pattern editing functions really going to be available while the 
> >sequencer is running? because that would make this the machine i've 
> >been looking for for years..

To which Paul answered:
 
> Forgive my impudence for answering in Colin's place but as a proud P3
> owner I'll say: you don't have to stop the music to do anything. 
> You can even edit the scales used in FTS, enabling and disabling notes
> as it plays. Very nice....

I thought I might add a little more detail so you know where I'm coming
from...

The P3 software is essentially divided into two main processes that run
on the same CPU and share the same data.
There's a third process that deals with LED refresh, and key and pot
scanning, but it's not as important.

The sequence playback engine is interrupt driven. It runs each time a
midi clock is received, or when the internal timer triggers it.
All it does is to read status information from memory, about pattern and
playlist positions, track status and so on, and use it to decide which
pattern data should be sent out the midi interface.

The main user interface process runs continuously (unless interrupted by
the playback or hardware scan process, but it is not 'aware' of this
happening).
It handles all the reading of keys and knobs, the changing of track
mute/unmute status, pattern and playlist editing, selection of parts and
so on.
Essentially all it is doing is reading and writing values into memory
areas that are shared with the playback process, writing information to
the LCD display, and updating status tables for the LEDs that are acted
upon by the hardware refresh process.
It reads the status of the keys and pots from tables updated by the
hardware process too.

It was a primary design requirement of the P3 that the pattern data be
organised in such a way that it is always consistent.
No single byte change of the pattern or part memory can cause a problem
to the playback engine. So there is no reason at all why the main
interface will operate differently whether or not the sequence engine is
running, unless there is an advantage in doing so (for example,
running/not running behaviour of the 'adv' function in playlist edit).

To me, having a sequencer that you have to stop to do something, and
then restart afterward, would be like a synth where the sound cuts out
while you are turning a knob, and only re-appears when you have stopped
the knob in its new position.

The only time you will need to stop the P3 is probably going to be when
doing a sysex dump of the whole memory.
You're not going to fit that down a midi cable along with note messages
and get anything like a musical performance out of an attached synth.

Cheers,
Colin f