An error condition that changes the normal flow of control in a program. An exception may Be generated ("raised") By hardware or software. Hardware exceptions include reset, interrupt or a signal from a {memory management unit}. Exceptions may Be generated By the {arithmetic logic unit} or {floating-point unit} for numerical errors such as divide By zero, overflow or underflow or {instruction decoding} errors such as privileged, reserved, {trap} or undefined instructions. Software exceptions are even more varied and the term could Be applied to any kind of error checking which alters the normal Behaviour of the program. (1994-10-31)