datapath

A datapath is the collection of hardware resources in a computer system that perform data processing. It encompasses the components that move data and apply operations to it, while the control unit determines which operations to perform and when. The datapath is typically contrasted with the control path, which sequences operations and manages instruction flow.

Core elements of a datapath usually include registers to hold operands and results, an arithmetic logic unit (ALU) or floating-point unit (FPU) for calculations, and supporting logic such as adders, shifters, multipliers, and comparators. It also includes the data interconnects that move data between components, such as buses, multiplexers, and decoders, and interfaces to memory and I/O. The width of the datapath, for example 8, 16, 32, or 64 bits, determines how much data can be processed in a single operation.

In operation, the datapath carries out the execute phase of instructions, reading operands from registers or memory, applying the requested operation, and writing results back to registers or memory. The same datapath may support multiple operations, with the control unit providing the specific control signals.

CPU designs vary in how they organize the datapath. A simple single-cycle processor implements all required operations in one clock cycle via a single datapath. A multi-cycle design splits the datapath into stages, allowing different operations to occur in sequence over several cycles. A pipelined processor adds registers between stages to improve throughput by overlapping instruction execution.

Design considerations for datapaths include timing, data hazards, and routing efficiency. Techniques such as forwarding, stalls, and careful control signaling help maintain correct and efficient data processing. Datapath concepts also apply to broader digital systems and signal processing architectures.