@Hawkeye Thanks :)
It's actually 8 tiny 7-segment display modules. It's controlled by an MAX 7221 and an Arduino (ssshh, don't tell anyone else on the forum) the keypad matrix is scanned by the same "microcontroller". It's not documented anywhere no. It has a MIDI In circuit, and the code just pass it on to the WAV trigger. The key presses send Note On and Program Changes.