Ural 650
The Ural 650 is an electric guitar that was manufactured in the Soviet Union in the 1970s. Only around 25,000 were produced (according to this article from Premier Guitar), so they can be quite hard to find. Most are not very playable, but with a bit of love and work, they can be made to be very playable. The original output jack on the Ural 650 is a multi-pin jack (similar to a MIDI output) that may have been used to allow the control of multiple amps and/or channels with the buttons on the guitar. While it's strange, the Ural 650 is a unique piece of history, and you should try one out if you ever get the chance.