image courtesy of Kevin Lightner
"In 1974 RMI introduced it's first, and only synthesizer. Although it was housed in the familiar RMI case, it was a totally different design than any previous instrument. To my knowledge, it was the first digital designed synthesizer available on the consumer market. The instrument was probably years ahead in design, and not understood, except by the professional musician.
"The instrument was monophonic, with two independent digital harmonic generators. Each generator's waveform could be modified independently, effectively like having two synthesizers by depressing one key. The unit had AM and FM control, and voltage controlled filters. Its own expression pedal controlled each audio output.
"The instrument listed for $2995, and was manufactured through 1976." ---Tom Emerick, Allen Organ Company
"The Harmonic Synthesizer - a precise approach to synthesis. You are given accurate control of waveforms by Digital harmonic Generators [2 digital oscillators with 16 sliders for producing frequencies 1x to 16x]. At your command are relative intensities of all overtones to beyond audibility! Each of the two digital harmonic generators produce an independent audio output for exotic contrasts in stereo. Preset waveforms can be selected or mixed with the generators for instant changes. Dynamic effects are created by voltage-controlled filters with low-pass, band-pass, and high-pass mixable outputs. [The envelope generator for the VCF is very strange on the Harmonic Synthesizer. It has a knob to select "Sweep Up", Sweep Down" and another knob for time.] Intricate melodic and rhythmic "sequencer" patterns are created by holding chords. Digital circuitry insures tuning stability and "drift-free" performance. The controls are rugged. The case is tough. RMI enjoys a history of building trouble-free instruments."----[from the RMI Harmonic Synthesizer's promotional brochure]