Not sure about Tron but here are a few details [1] about the Foonly F1 used on that film and how it was later used for Flight of the Navigator:
> They had pushed for Triple-I to build the DFP, the first (that I know of) high-resolution digital film printer for motion pictures. This was the next generation PFR, using an 8" CRT which had fast-decaying phosphors so that it could be used for scanning in film (using photomultiplier tubes built into a special camera) as well as printing. The imagery was amazing
> Since the Foonly only had enough disk storage to hold the frame being computed and the frame being printed, the numbers worked out like this: 30 seconds of film at 24 frames per second works out to 720 images each computed and printed at 6000 x 4000 pixels.
Tron was a mix of CGI and not-CGI. The not-CGI stuff, w/ all the photographic technique, was pretty wild. The CGI, in contrast, was not as wild.
I believe this was the documentary I watched a couple of years ago re: the making of Tron that went into a lot of detail about the effects: https://www.youtube.com/watch?v=sbgHMrLPQrE
Similarly, with early CGI like Tron, what was the render/target resolution for film?