Consider a real-time weapons control system aboard a fighter aircraft. Discuss which of the following events would be considered synchronous and which would be considered asynchronous to the computing system.

(a) A 10-millisecond, externally generated clock interrupt.

(b) A divide-by-zero trap.

(c) A built-in-test software failure.

(d) A discrete signal generated by the pilot pushing a button to fire a rocket.

(e) A discrete signal indicating “low on fuel.”