This design is an instant divining rod, separating the synth neophytes from electronic music gurus!
Back in the 60s, the Mellotron was a revolutionary new way to orchestrate multiple voices and tones. While the original models were intended to be used in the home with built in accompaniment--popular with Princess Margaret, Peter Sellers and L. Ron Hubbard--they became a portable and versatile tool for ambitious musicians.
They skyrocketed in popularity Mike Pinder chose it over keyboards and Hammond organs for The Moody Blues(featured prominently on Days of Future Passed and Octave)--Pinder introduced the polyphonic electro-mechanical, tape replay device to John Lennon and Paul McCartney who used it in The Beetles to write and record "Strawberry Fields Forever," Magical Mystery Tour and the White Album. King Crimson pioneered the keyboard in Prog Rock but they slipped out of favor after true synthesizers and samplers were introduced in the 80s.
Tron was a groundbreaking sci-fi film in 1982, nominated for multiple special effects and sound awards. While the story may have underwhelmed critics, the revolutionary computer animation techniques and set and costume designs by French Comic book artist Jean Giraud(aka Moebius), Syd Mead of Blade Runner and a commercial artist, Peter Lloyd opened new doors of possibility.
It was the daring soundtrack by Wendy Carlos that earns this films place in synth history though. Carlos utilized a Moog analog synth and Crumar's GDS digital synthesizer which was blended into traditional recordings of the London Philharmonic. Carlos had already achieved amazing results with her Switched-On Bach album and scores for Stanley Kubrick's A Clockwork Orange and The Shining.