amazing video here - most of the instruments are pre-synth, but there's some cool old-skool synthage to be had. Cool to see 360 Systems and RMI represented. :D
In case you're curious, the RMI featured a sort of card reader; you either filled in little squares or punched holes (don't remember which) to "draw" the waveform you wanted, and the RMI would read the waveform and create it.
Its 2 most famous users were Rick Wakeman (on his 2nd go-round with Yes) and Roger Powell, who used one both with David Bowie and with Utopia.