Re: Ah, memories.
"One use that I *do* remember was printing off grids of greyish, round-edged squares to represent an enlarged line screen of a print job, then overlaying them and gradually rotating them until they produced a moiré."
I used that trick to show animated data flow paths by moving one slide over another. Then we got one of the monochrome LCD panels mentioned up-thread. As mentioned, you had to be careful with animations due to the rather slow refresh rates in those days.
Biting the hand that feeds IT
