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 managementunit. Exceptions may be generated by the arithmetic logicunit or floating-point unit for numerical errors such as

divide by zero, overflow or underflow or instructiondecoding 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.