Integrated harmony generating circuit for electronic organ

Abstract

A harmony signal generating system for an electronic organ comprises a plurality of integrated circuit chips which each receive upper and lower manual keying signals for two consecutive organ notes. A first read only memory (ROM) generates octave identify signals to designate the octave of an active upper manual note. A second ROM generates octave select signals which are combined with the octave identify signals in a third ROM to generate the harmony signals which comprise the lower manual chording signals played through the upper manual within a twelve note range above an active upper manual note and an upper manual note which is one octave above the active upper manual note. The octave identify signals are provided in parallel among the chips from the chip having the lowest active upper manual letter note. Upper manual active signals generated in response to the upper manual keying signals are connected in series among the chips to select the appropriate chip. Internally generated octave identify signals are used on each chip which receives an active upper manual keying signal to accurately generate upper manual notes one octave above active upper manual notes when more than one upper manual key is depressed.