Abstract: A digital tone generator includes a modulo adder, an increment number register, two latches and a master clock. The adder continuously adds one of a plurality of predefined increment numbers with the adder's previously generated sums to create further sums and a carry output corresponding to one of a plurality of predetermined output tone frequencies. The system characteristics and increment numbers are selected to correspond to the predetermined frequencies and generate exact tonal frequency signals. The system characteristics and increment numbers are defined using a formula which accounts for the least common multiple of the rational number representation of the predetermined frequencies. In the preferred embodiment, the digital tone generator is used to select and generate one of a plurality of time code tones.