Everything. He would sit behind me and dictate keystrokes (mostly driving emacs, of course) to do email, edit code, and generally operate the computer. I don't want to talk about someone else's medical situation, but I think it's well-enough-known that rms had a period of RSI so severe that he was barred from using a keyboard to let his wrists/hands recover.

A few hours in a row of hearing and typing C-Space C-u 2 4 M-w C-x C-b <RET> C-y C-x C-s is exhausting. It was also amusing (in retrospect) to get a polite-enough admonishment to "don't think about what the keystrokes are doing; please just type what I say" when he could tell that I was slowing down because I was paying too much attention to what the intent behind the keystrokes was.

Wow that must have been fascinating. Did you end up learning a ton of emacs-fu along the way, or did it sorta start to just flow through you?

If I were in either of your shoes (sandals?) in that situation, I’m sure I would be super frustrated all the time. Impressive on both your parts.

I learned a lot, but I wish I could have gutted it out for longer in order to learn more about emacs and gcc internals. (I knew "we" were doing some maintenance on gcc because I remember asking questions about a comment that said "this is a win" and asking rms if we were working on gnu chess and him telling me that it was a compiler optimization. [Yeah, that's how amazingly skilled I was at the time.])

I ended up doing 4 sessions totaling about 10 hours and when I told him I was quitting, I was apologetic that I felt like I'd wasted his time quitting so soon after starting. His response I can remember to this day and it was something like "Don't worry about it; most people quit after the first session. You helped me out and we'll make sure you get your check."

That's amazing, it feels similar to people playing chess in movies (not sure if it happens in real life) without the board, just remembering the positions.