What was the deal with the dual round CRT displays? Something on the left was displayed different than on the right? Code / data?
Back in those days, CRT displays were extremely rare. Teletypes of various kinds were the norm. The dual display shown is an operator's console. The programmers typically submitted jobs on decks of punched cards and got their results from a line printer.
At the University of Colorado, the main operator's console (similar to that shown) was visible through a window in a viewing area. One of the two screens showed which "jobs" the computer was working on at the time and their status. The other screen was probably for operator commands and the associated system responses.
Our system had one "real" graphics display in another part of the comp center that could be used by programmers, which also had a large round CRT. I think it was used only by a couple of specialists and the Colorado highway department, who used it to plan mountain highways.
What was the deal with the dual round CRT displays? Something on the left was displayed different than on the right? Code / data?
They were vector scopes, not raster. Usually one showed the Dayfile or the Control Points (kinda like Task Nanager on a PC). The other scope was for running console programs like the O20 editor.
One of the PPUs directly controlled the electron gun behind the cathrode ray tube. It was like an Etch-A-Sketch, where each character on the screen was drawn in software one letter at a time.
Since it was vector drawn it could update far faster than any modern screen. Because of that it had some pretty cool games. Oops, I mean demos :-) The original Asteroids arcade game was one of them. There was also a two player Spacewar.
Like today - one monitor for work, one to surf the net on...just kidding.