Drawbar Strip

A tonewheel organ's registration control: N sliding bars with nine detents each, coloured in the classic brown/white/black families, and the registration printed underneath as the digit string players actually speak ("888000000"). The throw is inverted — out is loud, so the head travels down as the value rises — and the travel is detented rather than continuous, so a drag and a keypress cannot disagree about what "6" is. Press anywhere to jump a bar to that detent and keep dragging, wheel a notch at a time, or drive each bar from the keyboard. Layout, quantisation and key handling sit in a pure core beside it.