That puts Linux right up there with my AMIGA OS. Don't get me wrong..I am a Linux fan, but a 1% penetration is not worth writing about.

The navigation system on early missile boats had no hard drive. The used a rotating drum. The drum was slightly conical so that an adjustment screw could raise it up/down slightly to change the distance between the drum an the surrounding read heads. If you went to far (we did) the drum would wipe out against the read heads. Then you spent a day disposing of a drum with secret data on it. Fun days !

Literally, in the bilge of a nuclear submarine. Basic and machine code for a Varian computer circa 1974.

The Feynman lectures. The MIT video physics courses (free on the internet)are very good.