The movie name "Tron" came from a keyword implemented in
BASIC, especially the
Microsoft flavor included with
IBM PCs in the original 1980
ROMs.
TRON stands for TRACE ON, and sets the BASIC interpreter into a debugging mode. Every time a new line of the BASIC code would execute, the line number would get PRINTed. Presumably, the programmer would be able to see whether all of the lines in a subroutine were being executed as expected.
In the movie, Tron was a program that was designed to audit the other programs running in the mainframe computer. Metaphorically the same sort of idea.
The command to turn off BASIC Trace mode was TROFF, not to be confused with the Unix command troff(1) (table run-off formatter).