See also the evil interview question, "how does a keyboard type characters into an Emacs buffer?"

You could spend 8 hours describing it from power, to USB descriptors, to debouncing, to keymapping, to matrix scanning, to ptys, to editor string management algorithms to Lisp. And passing by this article as well!

Do you have a link? I can't find anything under that title.

Nah it's just an interesting interview question if you are looking for a generalist. There's also "what happens when you type into the address bar of your browser and hit return?" Can cover DNS, wifi, BGP, servers, DOM layout, TLS, etc.