Abstract: A tone pattern generating system for use with an electronic musical instrument, such as an electronic organ, responds to depression of a pedalboard key and a preselected rhythm and chordal pattern in an ROM memory to produce a "walking bass" automatically in response to continued depression of the selected pedal key. The ROM memory may be programmed to produce different tonal and rhythm effects in accordance with the wishes of the musician. In addition, provision is made for starting each rhythm and tonal pattern controlled by the ROM memory at the beginning of the pattern each time a new pedal key is played or released and replaying of the same pedal key is effected by the musician. The system also operates to immediately play the note selected by depression of the pedal key and prevents the production of tones under control of the ROM memory for a predetermined time interval following initial depression or operation of a pedal key.