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2 years ago in Hardware and Architecture By Shobha

How do you calculate CPU cycles for an instruction in a given datapath?

What are the steps involved in calculating the CPU cycles consumed by an instruction as it moves through a datapath's stages?

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By Rani Answered 1 year ago

To calculate the total CPU cycles for an instruction, you must analyze the sequence of operations within the datapath's pipeline or multi-cycle structure. Taking a 'word add' instruction as an example, it sequentially proceeds through the stages of Instruction Fetch, Decode/Register Read, Execute (where the ALU performs the addition), Memory Access (often skipped for ADD), and Write Back. In a standard pipelined design, each of these stages typically consumes one clock cycle. However, a definitive count requires examining the specific datapath diagram to account for its design, potential data hazards, and control logic, ultimately summing the cycles needed for all necessary data transfers and computations.

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