Instruction cycle

wikipedia Instruction cycle

The instruction cycle (also known as the fetch–decode–execute cycle or simply the fetch-execute cycle) is the cycle which the central processing unit (CPU) follows from boot-up until the computer has shut down in order to process instructions. It is composed of three main stages: the fetch stage, the decode stage, and the execute stage.

This is a simple diagram illustrating the individual stages of the fetch-decode-execute cycle.

In simpler CPUs, the instruction cycle is executed sequentially, each instruction being processed before the next one is started. In most modern CPUs, the instruction cycles are instead executed concurrently, and often in parallel, through an instruction pipeline: the next instruction starts being processed before the previous instruction has finished, which is possible because the cycle is broken up into separate steps.[1]