So honestly I don't quite remember if I encountered this with the Wangs, or if I'm recalling my Dad telling me about it from his experiences.

If the latter then odds are that it was either a machine from Wang and in that case most likely the 2200, or otherwise it will have most probably been equipment associated with the Gamma 10 from De La Rue Bull, or possibly the Ferranti Pegasus - both of which I know he worked with.

Of course, he might have been telling me a third-party anecdote in which case it's possible the IBM Display Station was the machine in question.

That all said, last time I was discussing this with someone they mentioned that the 2200's terminal had a "solenoid" trace on its PCB so it's quite possible that this really was the relevant device. Last time I personally had hands on a live 2200 was about 1993 though, so I really can't be sure.

There's a chap in the Netherlands with a Wang 2200 museum - perhaps I should just write to him and ask :D