Today a friend tried to explain the concept of circuit emulation to me. It's like this: a program can be debugged by inserting break-points selectively within it, but a circuit board is a tiny hardcoded program chip with no break-points (to put it in layman terms). To trouble-shoot an erroneous circuit board, a larger emulator is used to simulate the circuitry and yet allow for break-points to occur. So I learnt something new today. How nice. :)