The original Apple Macintosh (like most other early computers) ran all the time in "supervisor mode". The processor could do whatever it wanted to—or rather, whatever the machine-language instructions told it to do—and so any program could run amok, overwrite another program's data, and crash the entire computer if a programmer made a single fatal mistake.
Modern operating systems, in contrast, run ordinary programs in "user mode". The processor is limited in what it can do, crashes are much less frequent, and when a program fails it can't take down other programs. Supervisor mode is reserved for the operating system, the master controller. It monitors what's going on, and can if necessary force individual programs to take turns and play nicely with one another. In extreme circumstances it can interrupt and shut down a user-mode program that goes astray.
Speculation: perhaps higher-level self-awareness—such as that cultivated by mindfulness meditation—sets up something like a modern computer operating system? A part of the mind stands apart and quietly watches the rest. It need not judge or interfere; it just observes. Maybe that's enlightenment?
(cf. EngineeringEnlightenment (1999-10-09), Wherever You Go, There You Are (2008-10-26), Coming to Our Senses (2009-01-01), Bind the Monkey (2009-11-21), Finding the Quiet (2009-12-05), Being with Your Breath (2010-02-20), ...) - ^z - 2010-04-13