The Yamaha VP-1 is one of the rarest production synthesizers, with somewhere between 8 and 15 still in existence, it was Yamaha's top tier synth design project - kind of like Formula 1.
Pro Synth Network recently devoted a couple of hours to the details, sounds and stories surrounding this unicorn of an instrument - it was an early foray into physical modeling and required a vast amount of on aboard computing power at a time when that was pretty expensive.
Dr. Manny Fernandez:, Reinhold Heil , Scott Kinsey, Ben Simpson, Kent Spong and Rob Puricelli
There's also since been a sounds only demo:
From Earmonkey Music
Hold on, there's more
Matths gives it a workout