In October 1964 Robert Moog demonstrated the prototype Moog Synthesizer at the Audio Engineering Society convention held in New York City. It was the first substractive synthesizer to utilize a keyboard as a controller. Moog discussed his innovations in a paper that he presented at the conference: "Voltage-Controlled Electronic Music Modules". This paper was published in Journal of the Audio Engineering Society, Vol. 13, No. 3 (July 1965) 200–206.
Moog began his career in 1954, manufacturing Theremins. In the video below he demonstrated both his Synthesizer and the latest Theremin offered by his company.
"There were two key features in Moog's new system: he analyzed and systematized the production of electronically generated sounds, breaking down the process into a number of basic functional blocks, which could be carried out by standardized modules. He proposed the use of a standardized scale of voltages for the electrical signals that controlled the various functions of these modules—the Moog oscillators and keyboard, for example, used a standard progression of 1 volt per octave for pitch control."
"The Moog synthesizer gained wider attention in the music industry after it was demonstrated at the Monterey International Pop Festival in 1967. The commercial breakthrough of a Moog recording was made by Wendy Carlos in the 1968 record Switched-On Bach, which became one of the highest-selling classical music recordings of its era" (Wikipedia article on Robert Moog, accessed 12-01-2013).