In a comment on yesterday’s photograph Judith mentioned “the computer people in the basement”. Well, this is he. Jon the wizard in the basement about to make the mainframe jump through another hoop (or perhaps “loop”). It was a tricky task, the pen had to be held in the mouth “just so”.
Trivia: A DEC VT100 terminal on the left, and a Lear Siegler ADM-3A, or ADM-5 on the right.
lookANDsee 
Wasn’t it wonderful to be able to type commands on a keyboard and see the results on the screen. The VT-100 had the ability to create screens allowing text entry in fields. The VT-100 probably has less processing power than a current washing machine and the mainframe would have less than a cars engine management system.