[2] When no instrument emerged, in early 1977, Smith quit his job to work full-time on a design for the Prophet-5, the first fully programmable polyphonic synthesizer.

He demonstrated it at the NAMM International Music & Sound Expo in January 1978 and shipped the first models later that year.

[4]: 385  The Prophet-5 became a market leader and industry standard,[6] used by musicians such as Michael Jackson, Madonna, and Dr Dre, and by film composers such as John Carpenter.

[9] Smith and the Sequential engineer Chet Wood designed an interface using Roland's Digital Control Bus (DCB) as a basis.

[11][12]: 20  The protocol was named Musical Instrument Digital Interface (MIDI)[13]: 4  and unveiled by Kakehashi and Smith, who received Technical Grammy Awards in 2013 for their work.

[2] In 2008, Dave Smith Instruments launched the Prophet '08, conceived as an affordable eight-voice analog synthesizer.

[2] In January 2015, Yamaha returned the Sequential Circuits brands to Smith in a goodwill gesture.

Kakehashi said: "I feel that it's important to get rid of unnecessary conflict among electronic musical instrument companies.

For this reason, I personally recommended that the President of Yamaha, Mr. Nakata, return the rights to the Sequential name to Dave Smith.