Usually, the time required for the execution of one simple processor operation such as an addition; this time is normally the reciprocal of the clock rate. The term has been used formerly for the time required for the fetching and execution of one simple (e.g. add or subtract) machine instruction; this use however is inappropriate now when most processors exploit pipelining. The CPU cycle time is one of many figures-of-merit for a computer system. See also computer power, cycle.