I remember playing Digger on my IBM PC clone sold by AT&T (6300) back in 1987 or 1988. I also remember that the game speed was set to some factor of the comput

I remember playing Digger on my IBM PC clone sold by AT&T (6300) back in 1987 or 1988. I also remember that the game speed was set to some factor of the computer's clock speed. When I later tried to run the same game after I upgraded my hardware, the game went so fast, you could not even play it.