When in user mode, the two keyboards will be "connected to the circuit": for each keyboard, the button presses will generate a UI input signal and the (multiplexed) UI output signal will be shown as lights.

Internally, a UI signal is just a set of boolean values that tell if a key is pressed down (1) or not (0). In user mode, each keyboard generates an 8x8 UI signal from its keys and receives an 8x8 UI signal that it displays as lights.

There are also four user controls which are small (2x1) user interfaces that are accessed through the top row of the right keyboard. Unlike the two "main" user interfaces, these user controls can be accessed in user mode as well as in editor mode. The user controls are "input-only" interfaces.

For the moment, the main purpose of the 8x8 user interfaces is to provide notes to the synthesizers, while the user controls allow to increase and decrease numerical "parameters".