It's interesting that with the very old stuff like that rectifier tube, you can actually see it working. Think of the old reel to reel computer tape drives and a solid state drive of today. You really can't call it a hard drive because it has no moving parts and you can't see it working. I remember being able to see the movement of the stepper motor moving the heads on an old MFM hard drive I had in an IBM PC. I'm not going to live long enough to see automobiles without wheels. The darn things will probably fly or be magnetically levitated. The movement of technology is making things faster and smaller but if there is some calamity that knocks out the supporting infrastructure, it's the old clunky stuff that will be the only things that will work. ^_^
TDD