While preparing to write this chapter, I remembered a real-time systems course in college. Not the whole course, of course, but one of the tasks we were given --one of the most interesting ones, if not the most interesting. We had to write a small program that would display a text string that should move from left to right and back again on the screen until a certain key was pressed on the keyboard. Two additional keys would make it possible to control the speed of the string's movement. It was 2001 or 2002, we were still using DOS for Assembly-related exercises and the task appeared to be quite simple.

I personally found it extremely boring to use DOS interrupts for this purpose (I had no idea of Occam's Razor principle at the time, besides, I wanted to look smart), so I decided not to use any OS at all. My laptop had a floppy drive, so the...