Automated Lighting, by Richard Cadena. Focal Press, 2006, does a very good job of documenting the history of moving lights.
I'm moving this thread to from "Off-topic" to "Lighting," as I feel it deserves a more prominent place.
Van, that sounds like you are describing the controller for the MAC ACR, not the PanCan (as the PanCan didn't have a dedicated controller). Was the "fixture" base round and red, about 18" in diameter?
It could have also been a Moto-Yoke, by Dyna-Might Sound and Light--I never saw a controller for one of those.
Our beloved Strand Lighting had, in the 1980s, the ParScan, a moving PARcan, which most people nicknamed the ParScam, due to the fixture's lack of reliability.
Oh and for what it's worth.... I was talking to Gordon one day about the "History of moving lights" he told me one of the funniest things about Vari-Lites was that when they first demonstrated the things to Genesis, they were intended to only be a fixture capable of "refocusing" in the middle of a show. It was purely an accident when someone left the shutters open on a bank of them, and then moved them to their next position. Apparently everyone went nuts, "Do it again Do it again" and the rest is history