Abstract: A musical input device accepts user input and generates output data indicative of musical notes. Based on a selected musical scale, a first set of keys is configured, such that each key of the first set outputs a respective chord associated with the scale. A second set of keys may be configured to output individual notes from the scale, or chords that are associated with a different scale. The keys may be provided with visible indicia, such as a color indicating the root note of a chord. Visible indicia may indicate relationships between keys, such as a melody note that matches the root note of a chord. Control keys may be used to add notes to chords or modify notes in chords, such as by adding additional octaves to the output or modifying the voicing, inversion, or spread of a chord.