Elevators aren't computers (unless they have a part that is a computer), but my question is related. From experience, I made what I call "the elevator riddle." How do you make an elevator unlight a button without going to that floor? The elevator works properly, and you can't break it or push an Emergency button. The answer is to push buttons in opposite directions. Where I work, when the elevator gets to the bottom, it unlights all the buttons even if there are higher floors it hadn't gone to. I would think there would be a way of programming elevators to leave the buttons lit and go to those floors when it reaches the bottom (or top). This was true for two elevators, so I'm assuming it's how elevators are normally programmed.