Unlike a piano or an organ, early synthesizers like Moog and ARP could only produce one note at a time. In order to shape a certain tone, several knobs, switches or controls had to be adjusted, and trying to reproduce that tone afterwards meant writing down all the settings and hoping to get similar results next time.
The Prophet-5 that Mr. Smith designed with John Bowen and introduced in 1978 overcame both deficiencies. By controlling the synthesizer functions with microprocessors, he was able to play five notes at once, allowing for harmonies. (The company also made a 10-note Prophet 10.) The Prophet also used microprocessors to store settings in memory, providing reliable yet personalized sounds, and it was portable enough to be used on stage will.
Mr. Smith’s little firm was inundated with orders; At times, the Prophet-5 was two years behind.
But Mr. Smith’s innovations went much further. “Once you have a microprocessor in an instrument, you realize how easy it is to communicate digitally with another instrument that has a microprocessor,” explained Mr. Smith in 2014. Other keyboard manufacturers began incorporating microprocessors, but every company used one different, incompatible interface, a situation Mr. Smith said he thought was “kinda stupid”.
In 1981, Mr. Smith and Chet Wood, a sequential circuit engineer, presented a paper at the Audio Engineering Society convention to make a proposal “The ‘USI’ or Universal Synthesizer Interface.” The point he recalled in a 2014 interview with Waveshaper Media, was “Here is an interface. It doesn’t have to be like that, but we really have to all get together and do something.” Otherwise, he said, “This market is going nowhere.”
Four Japanese companies—Roland, Korg, Yamaha, and Kawai—were willing to collaborate with Sequential Circuits on a common standard, and Roland’s Mr. Smith and Mr. Kakehashi worked out the details of what would become MIDI. “If we did MIDI the usual way, it would take years and years and years to develop a standard,” Mr. Smith told Waveshaper. “They have committees and documents and da-da-da. We got around all of that by just doing it and then throwing it out.”
In 2013, Mr. Smith narrated The St. Helena Star: “We made it cost-effective so it would be easy for companies to integrate it into their products. It was given away royalty-free because we wanted everyone to use it.”