Lukas' Notes

computer-architecture

Definition

Pipelined Functional Unit

A pipelined functional unit is a functional unit whose internal operation is divided into multiple independent stages. Each stage can process a different operation simultaneously, so the unit accepts a new input every clock cycle — even though a single operation takes several cycles to complete.

A pipelined unit has latency cycles but throughput of one operation per cycle. Only dependent operations pay the latency; independent operations benefit from full throughput.

Example

Pipelined multiplier

A floating-point multiplier is typically pipelined across 3–5 stages (mantissa multiply, exponent add, normalise/round). It accepts a new multiply every cycle while earlier multiplications flow through later stages. The pipeline registers between stages isolate each partial computation.