Abstract: An electronic musical chord calculator suitable for embodiment using integrated circuitry, has finger-actuatable devices for specifying notes (13) and chords (14). A display (11) has indicator devices (12) for each note of any chord to be specified. Logic circuitry (m21) serves to produce one chord automatically and immediately. Other logic circuitry (m21) serves to produce other chords by logic operations to add or substract notes relative to the basic chord. Other embodiments produce all required chords for one note automatically and immediately, then produce chords for other notes by shift operations (29) from the chords for the one note.