Reusing the ALU in a Datapath

Hierarchy lets a larger design reuse a tested block instead of rewriting it. An ALU instance exposes a small interface: operand inputs, an operation select, and a result output. The surrounding datapath connects those ports to its own wires.

Named port mapping makes the connection roles clear. It shows which wires are operand values, which wire is the operation control, and where the resulting value continues. The ALU stays focused on computation; the surrounding design owns routing and storage.

That boundary is valuable during debugging too. If a result is wrong, inspect the ALU behavior separately from the signals that fed it and the destination that received it.