It’s amazing that this computer that I had never heard about was being sold until just recently (2004). You would sure feel like a computer programmer when you were working on one of these, pushing buttons, turning knobs, plugging patch cables from one port to the next… I don’t think many other systems could ever have a life as long as this unit had.

"Each GP-6 is a self-contained unit capable of simulating linear and non-linear systems of up to four state variables. Over 2000 GP-6 analog computers have been installed in over 400 university, government and commercial research laboratories."

Via: RetroThing