[msarnoff]

Storage tubes are amazing. I once had a Tektronix 464 scope. Unlike the ubiquitous 465, the 464 was an analog storage oscilloscope! The persistence of the storage tube let you capture pulses, visualize signal jitter, etc. And there was a very satisfying erase button that cleared the tube with the characteristic green flash.

You could also just mess with the horizontal/vertical position knobs and use it as a very expensive Etch-a-Sketch.

[pragma_x]

It's been a while, so I went to Wikipedia for a refresher. These things really are amazing.

https://en.wikipedia.org/wiki/Storage_tube#Storage

Unlike a television CRT, the storage tube will "remember" everywhere the electron beam struck the screen as long as the voltage is below the erase threshold.

What's wild is that this information can be read back out of the device. So, it's not just a display but also memory. It's a destructive reading process (not unlike core memory) where detection is also erasure, but it really is RAM... of a sort.