[doogieboo]

Vacuum tubes are his specialty area. He's building a much larger vacuum tube computer and this is supposed to be a more mobile display version he can demo at events.

He's also done quite a few videos restoring old vacuum tube based test equipment from like HP. He does some really cool work.

[II2II]

Well, he described the single board version as a trainer: a way to demonstrate how the larger model works. That's likely why the address/data lines are toggle switches and the close is a button. People can setup the state then execute when ready. The much larger version is the thing you see behind him on the wall (it is a work in progress). It is also intended to go to events, but it is much harder to understand ... thus the trainer.