“When any CPU includes hardware that decides to redirect the CPU’s attention to a new program regardless of the nature of the current program we have an interrupt. […] A program comes to a presumably rare situation where the CPU cannot obey the program given the unusual state of the computation. This is a situation that is either unanticipated by the programmer, or anticipated but inefficient to explicitly program for. An example of the latter is division by zero where the application author has not yet decided what to do in such an unlikely event. I call these traps here and say that the program has been trapped.”

- “History of interrupts”