Replying to
@nixCraft@mastodon.social in the early '70-ies I used disks like those, but a little smaller in diameter - 19". 4 platters in a removable stack for 30MB. The drive was the size of a washing machine and used 3 phase 400v at 16amps. We had instructions not to turn it on if the temperature was below 19° centigrade as the coating risked flaking off.
Now I have 2TB on a usb-stick 🤔