Last week I was at a conference at the Computer History Museum in Mountain View and saw one of this in real life for the first time in, easily, 38 years, and it brought tears to my eyes.
If you're ever near this place, I recommend a visit to this museum. It was my first time, but it won't be the last. I hope I can go back and take my kids there once. I left with a punched card with my login name punched into it, using the keypunch of the (working) 1401 that's on display.
In the mid-to-late 80s, my school still had a lab of 10 or so PETs. All connected to the same dual floppy unit. I remember the teacher would tell half the class to save their work, then flip the floppy over for the rest of the class.