Flynn said MICRO cycles.
I just read an interview with the writers. they specifically said micro cycles.
Found here: http://blog.moviefone.com/2010/12/21/tron-legacy-screenwriters-interview/?a_dgi=aolshare_facebook
Specifically this quote: "In terms of the time cycles, is the passing of time, for lack of a better reference, like 'Inception' where like one minute in the real world is like 10 minutes in the computer world?
Horowitz: Yes. There is a very complicated mathematical formula that we worked on to make it work. And we went back and forth because we had versions where Eddie and I, math is not necessarily our strong suit, where we would have Kevin Flynn was in there for 28,000 years.
Kitsis: It sounded great in the script - it's like one cycle equals eight hours, but we were like, oh, so he's been in there for a million years?
Horowitz: We worked it out with Joe and we call them microcycles and there are divisions. And I think it's something like, a microcycle is like eight hours or we sort of basically we figured it out. But the concept is when you're in the grid, your time is working at a different rate than it is out here."