Key code data generator

Abstract

Key switches are connected in a matrix fashion between row lines making block lines for octaves and column lines making note lines for notes. The note lines are connected to a note detection circuit which converts the note line outputs of the actuated switches into key codes in a time shared fashion and to a chord detection circuit which includes a chord type detecting logic and a shift register connected thereto and storing the note line outputs in its respective stages. During a chord detecting period, the note detection circuit is loaded with signals '1' as if all the key switches were actuated and delivers key codes of all notes one after another, whereas the shift register is circulatingly shifted synchronously with the note code change. When the logic detects an establishment of a chord, the note code of that moment is extracted to be a code identifying the root note of the chord. The root note code is then processed for automatic bass and chord performance.