Great pictures. In one picture there is some flowchart on chalkboard. I'm always curious on how did flowchart symbols came to be. For example I'm pleasantly sur

Great pictures. In one picture there is some flowchart on chalkboard. I'm always curious on how did flowchart symbols came to be. For example I'm pleasantly surprised that the disk plate/drum symbol (used to signify databases) that is drawn on chalkboard, which is prevalent nowadays is also used in 60s.