Programmable tone generator

A digital electronic tone signal generating circuit for an electronic musical instrument comprising:

• a clock, digital counter means having an input connected to said clock and having a plurality of outputs, a plurality of like tone signal branches each comprising a digital signal processing circuit including buffer means connected to selected ones of said counter outputs, adder means connected to said buffer, programmable variable number source means connected to said adder, comparator means connected to said adder and also to said selected counter outputs, and flip-flop means connected to said comparator and controlled thereby to produce either a logic 1 or logic 0 output, said selected counter outputs and said programmable variable number source means cooperating for controlling the state of said flip-flop means to construct a rectangular wave output of selected pulse width and pulse spacing in each tone signal branch, thereby comprising a composite tone signal of selected fundamental frequency and harmonic content for each tone signal branch, wherein said programmable variable number source means comprises means providing programmed fixed numbers, programmable means for generating further numbers and means for selectively adding said further numbers with said fixed numbers.