Sequential Circuits Prophet 5
Sequential Circuits introduced the Prophet 5, which was the first analog 5-voice polyphonic synthesizers to provide onboard memory storage of all patch settings for instant recall. The great-sounding Prophet 5 revolutionized the synthesizer world and, in spite of its rather expensive price tag, became one of the most successful synths of all time. Designed by Dave Smith and J owen, the Prophet 5 was the keyboard of choice by a very long list of performers that includes Peter Gabriel, Philip Glass, Journey, The Cars, Thomas Dolby, Duran Duran, Gary Numan, Pink Floyd, and countless others.
Image attribution: original uploader was Felix2036 at Dutch Wikipedia derivative work: Clusternote (Sequential_Circuits_Prophet_5.jpg) [Public domain], via Wikimedia Commons
Which brings us to 1977...