Knobs: drag up / down, the mouse wheel, or click the left / right half. Buttons: click (Shift-click holds one down, e.g. PLAY + PRESET for the tempo). Keys: click, or the computer keyboard A W S E D F T G Y H U J K (Z / X: octave).
Try: PRESET for the 33 factory patches · SEQ for the sequencer, PLAY to run it · SEL for the rack · HOME (on the module page) for the oscilloscope and the visuals · GLO, GLO, then K4: ENGLISH / ESPAÑOL.
This is the real FM-1 firmware's screens and controls compiled for the browser, with the editor's engine making the sound (the same engine, sample for sample). Patching on the rack page (EDIT) and saving work on the FM-1 itself; here, use the editor.