TBOSS: TheoryBoard Open Source Software

New life for your TheoryBoard

TBOSS is free, open-source firmware for the TheoryBoard THY333. Play chords and melodies by scale degree in any key, with strum, an arpeggiator, progressions, a step sequencer and full MIDI control. It installs from your browser in about a minute.

Chrome or Edge on Windows, macOS, Linux or ChromeOS · free under the GPL

A community project. TBOSS is not affiliated with, endorsed or supported by the makers of the TheoryBoard. It installs through the board's own update mode and never touches its start-up loader, so you can always reinstall it, or go back to the original firmware (how).

What it does

Out of the box it plays like a regular TheoryBoard. Everything extra is off until you turn it on, and the manual walks through each feature with an example.

Chords by scale degree

Pick a root and a mode: the left half plays the key's chords, the right half its scale. Chord names on the display.

86 scales, and your own

The modes of major and minor, pentatonics, blues, bebop, Messiaen's modes and more, plus 12 scales you make in the web editor.

Voicings and chord sets

Inversions, a real guitar voicing, spread and octaves; any 12 chords on the pads, or the original's full chord layout.

Strum, arpeggio, repeat

Strums with a human feel, an arpeggiator with Euclidean rhythms and tuplets, MPC-style note repeat, echo and harmony.

Progressions and steps

Record a song's chords and let the board play them in time, or build patterns in a four-lane step sequencer that follows your DAW.

Theory at your fingers

Hints light the chords that usually come next, pivot chords lead to a new key, chord capture finds the key you played in.

Expressive MIDI

Poly aftertouch, pitch bend or CCs from pressure, velocity curves, MIDI clock in and out, TRS MIDI out and a sustain pedal.

Installs from the browser

A USB cable and Chrome or Edge: no drivers, no tools. Updates keep your settings, presets and scales.

New in 2.0

Tested on a board (2.0.8). 2.0 also brings 1.9 and 1.8, not released on their own. Four things from the roadmap and two you asked for, then more:

More in the manual →

Get started

You need the TheoryBoard, its USB cable, and Chrome or Edge on a computer.

  1. Open the installer. Updating from an earlier TBOSS? Click Save settings first, and they come back after installing.
  2. Start the board in update mode: unplug the USB cable (and the power adapter), hold the top-left and bottom-left pads of the left half, plug the cable back in and keep holding for about 3 seconds.
  3. Click Connect, choose TheoryBoard, then Install TBOSS. It takes about a minute and the board restarts by itself.
  4. Play. Your computer sees a MIDI device called TheoryBoard MIDI; the center button below the screen opens the settings, and the manual explains everything.

Free, and it stays free. Every feature and every update costs nothing. If TBOSS has made your TheoryBoard more fun, you can help fund future development with a donation of any size. Entirely optional.