A circular, 1-dimensional cellular automaton that creates minimalistic compositions in an odd time signature.

This is a retry of a ZOIA patch with a cellular automata principle (see AUTOCELL patch), but instead of a full grid I’ve simplified it into a 1-dimensional grid (so a line :) that is wrapped around in a loop (I’d say a circle if it weren’t for those square buttons, so it’s more a rectangle I guess?).
The name ‘Rule 90’ comes from a famous automata variant, which uses the following simple rules: any cell with ONE living neighbour becomes (or stays) alive, and any cell with TWO or ZERO living neighbours dies.
You can manually SEED any of the cells of the ‘circle’ to become alive, and at every LFO tick this calculation is repeated and the pattern evolves and grows/shrinks accordingly.
Pitches are calculated by summing living cells with a unique weighing factor and summing them into a quantizer.

Ok, and now things are getting interesting: any seeded ‘living’ cell migrates in both directions and bounces back at the opposite end, and because there are 18 cells in the circle, the resulting patterns are always exactly… uhm, 14 steps long?! Yeah, that surprised me as well, but apparently it checks out mathematically! If this sounds complicated; don’t worry, it just means the little lights move around in cool patterns and create pretty melodies in 7-step beat!
I built most of this patch before ever listening to it, but turns out it produces very musical, minimalistic melodic patterns (a bit reminiscent of Steve Reich / Philip Glass), so I’m very happy with how this turned out!

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[OVERVIEW]
-Input/Output: Stereo in, stereo out
-CPU load: Around 102%
-Build: Initial version built on ZEBU with firmware 2.80
-MIDI: No MIDI in this patch. If controls are set to CC’s I use CC channels 21/36 (see CONTROLS section for details).

-CV Inputs:
1) Clock Trig
2) Seed Trig
3) Spread CV
4) Transpose CV
-CV Outputs:
1) Pitch Mid (1V/Oct)
2) Pitch Left(1V/Oct)
3) Pitch Right (1V/Oct)
4) Envelope (only triggered from the middle TRIG buttons)

[REVISIONS]
1.0: Initial patch.

[CONTROLS]
Most controls are on the “UI” page and are labeled (see below for a “Picture Manual” in the comments).
The Stereo Output module with gain parameter is on the “IO” page.

CIRCLE OF CELLS (the cells of the automaton; press to ‘seed’ cells manually; purple = alive, blue = dead)
TRIGS L/R/M (toggle to trigger notes when the neighbouring cells are alive; the middle ones only fire when both their upper AND bottom cells are alive)
LEVEL (sets the level of the internal synth)
SPREAD (determines the spread and maximum height of notes)
TRANSPOSE (tuning offset; located before the quantizer)

Additional controls on IO page:
LFO (sets the internal clock rate; use the switch below the LFO to switch to external CV clock input)
DECAY (sets envelope decay for all voices)
LPF (filter for the internal synth)
There is also the Reverb module and an Aliaser for the middle internal voice.

ZEBU LEFT button = RESET (clears entire grid).
ZEBU RIGHT button = SEED (toggles one or more random cells on the grid).
ZOIA stompswitches = Unused.

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[PATCH STRUCTURE]
Oof, I made this over a year ago and I know it was a complex one…
I’ll say this: its 14 pages long and there are a lot of S&H modules and CV switches, but no-one reads this part anyway so I’m not bothering re-investigating the details. :)

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[TIPS/TRICKS]
>>> Start with a slow clock speed and just seed a few buttons, then watch the pattern migrate along the circle and evolve. It’s fun (well at least I think so) to see if you can understand the rules of this Game Of Life!

>>> If you seed the buttons on the left-centre or right-centre, the pattern will bounce back and forth in a symmetrical fashion. If you seed any other button, the pattern will be more complex.

>>> If you want it to continuously evolve, just keep pressing the SEED button every 4 or 8 bars or something (either manually, or clock it via CV).

[THOUGHTS/IDEAS/PLANS]
This patch is done, no future plans.

If there’s any bugs/questions/remarks/requests or suggestions for improvement, please let me know!
Enjoy!

(Image: Yoshimitsu Umekawa)