Instruction cycle

<p>The instruction cycle (also known as the fetch–decode–execute cycle, or simply the fetch–execute cycle) is the cycle that the <a href="/facts/Central_processing_unit/Jxp1bqMV">central processing unit</a> (CPU) follows from <a href="/facts/Booting/j6N1kRpc">boot-up</a> 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. 
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<p>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 <a href="/facts/Concurrent_computing/yVzQBPr9">concurrently</a>, and often in <a href="/facts/Parallel_computing/nQzcpzQt">parallel</a>, through an <a href="/facts/Instruction_pipeline/3zy6CcX1">instruction pipeline</a>: the next instruction starts being processed before the previous instruction has finished, which is possible because the cycle is broken up into separate steps.
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Instruction cycle open-in-new

Instruction cycle