I took a closer look at that CDC setup and the box on the viewer's
right side appears to have a glass inset on the top, which would
probably make it not a controller but a 501 line printer (an 800 lpm
drum printer). The other cabinet on the left may also be a 501--this
would not be an atypical setup of the time. Still doesn't answer the
question of what the CPU is, but I don't think that can be answered,
unless someone recognizes the room itself.
Those 3000-series green glass enclosures were used for everything, it
seems in retrospect.
Cheers,
Chuck