Comment by kjs3
13 hours ago
I ran a lab of Apollo 3500/4500 era machine in college (thanks for poking that memory). None of them had RCA phono connectors for token ring, but they did have a really weird connector that looked like it had 2 coax(ish) connections, along with some pins, in a D shell. Think something that looks like a 13w3 video connector, but only 2 signals and fewer pins. Are you thinking of an earlier generation of Apollo machines?
We had some early models which had two ordinary coax lines going in. Unplug either and the ring went down. They probably converted to something with one connector, and maybe a mechanism to close the loop if unplugged. That's a basic problem with token ring - anything removed must be jumpered out.
We just had two loaners for a demo, so we might have been given an old model. We were evaluating workstations, and had various devices for a few months at a time.
I saw quite a bit of rare early hardware over my career. Much of it was rare for a good reason.