[Kludge]

Depending on It's condition, some Commodore 64's have sold for a decent amount of cash. I should've kept mine.

In terms of DOS prompts, I absolutely agree- I used quite a lot back then, but have forgotten the majority. I still have Windows 3.1, converted to a bootable ISO, with a capacity of only "8.5 MB".

I challenged my girl to figure out the Linux terminal just for shits and giggles one day, and she, having earned her CompSci degree THAT long ago, managed to remember 'dir' to display the current file tree.
I was a proud, proud man that day. Especially because she hates computers after getting that degree, so remembering one DOS command was heart warming.

It's hard to forget the DIR command.

"CD" was also commonly used.

Both being replaced in usefulness by 'ls'