An input device accepts user input and generates data indicative of notes, such as MIDI data. The input device includes a set of chord keys and a set of melody keys. A desired scale is selected, and the chord keys and melody keys are configured to utilize notes associated with that scale. The chord keys may be representative of all non-inverted chords associated with that scale. Inverted chords may be accessed using other keys or key combinations. Upon activation of an individual chord key, MIDI data representative of the notes in that chord is generated. Upon activation of an individual melody key, MIDI data representative of a single note from the scale is generated. Conflicts between notes associated with activated and released keys are resolved. Keys illuminated with a color associated with a particular note facilitate user recognition of that note in the chord keys and melody keys.

Disclosed are a spiral curve type music sheet in which different notes are displayed at different positions on a spiral curve based on the pitches of notes, and an apparatus and method for providing a spiral curve type music sheet. The apparatus for providing a spiral curve type music sheet may include a memory configured to store a spiral curve type music sheet in which different notes are displayed at different positions on a spiral curve based on the pitch of the note and note data, and a processor configured to determine the note symbol position related to the note data on the spiral curve in the spiral curve type music sheet based on the frequency of the note data.