Amusingly, there was an early "scientific" word processor for the IBM PC, that simulated the Selectric math ball. You pressed one of the extra keys (maybe "alt" but I don't remember) and got the alternative ball. You could also move up and down by half lines. It was very quick to type math.
I used it for my dissertation. The page numbering feature could not be adapted to my university's requirements, so I printed out my manuscript without page numbers, and pasted them in by hand, then had the whole thing photocopied.
