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Hedy

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What is pipelining in microprocessor?

Pipelining is a technique used in microprocessors(what is microprocessor?) to increase instruction throughput — the number of instructions that can be executed in a given amount of time — by overlapping the execution of multiple instructions.

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Analogy: Assembly Line
Think of it like a car factory:

  • Instead of building one car at a time from start to finish,
  • Different stations (like engine fitting, painting, testing) work simultaneously on different cars.

Likewise, in pipelining:

Different stages of instruction execution are processed in parallel.

Basic Pipeline Stages
Most instruction pipelines have these basic stages (names can vary):

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Example: Without vs With Pipelining

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In pipelining, a new instruction enters the pipeline every clock cycle, so multiple instructions are being processed at once — each in a different stage.

Advantages of Pipelining

  • Higher throughput
  • Better CPU performance
  • Efficient use of CPU resources

Limitations / Hazards

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Solutions include:

Forwarding, stalling, and branch prediction techniques.

Used In:

  • 8086 (basic pipelining: Fetch + Execute)
  • Modern processors (ARM, x86) with deep pipelines (10+ stages)
  • Super-scalar and out-of-order execution

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