基本內容
又稱機器周期，機器內部各種操作大致可歸屬為對CPU內部的操作和對主存的操作兩大類，由於CPU內部操作速度較快，CPU訪問一次記憶體所花的時間較長，因此用從記憶體讀取一條指令字的最短時間來定義，這個基準時間就是CPU周期(機器周期)。一個指令周期常由若干CPU周期構成。
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.
CPU周期