Coprocessors

A coprocessor is a separate processor or processing unit that augments a computer’s main CPU by handling specialized tasks, thereby improving overall performance and efficiency. Coprocessors can operate independently or in close coordination with the primary processor, typically communicating through a shared bus or dedicated interfaces.

Historically, coprocessors were used to accelerate functions that were slow when performed by the general-purpose CPU. A notable example is the floating-point coprocessor, such as the 8087 for the 8086/8088 family and the 80387 for the 80386, which provided hardware support for mathematical operations. Over time, many of these functions were integrated into the main CPUs, but the concept persisted for workloads that benefit from specialization.

Common types of coprocessors include numeric coprocessors (floating-point units), graphics and video processors (GPUs or graphics coprocessors) for rendering and parallel computations, digital signal processors (DSPs) for audio and signal processing, cryptographic accelerators for encryption tasks, and AI or machine learning accelerators for neural network workloads. In modern systems, GPUs frequently act as coprocessors to the CPU, performing massively parallel tasks beyond traditional graphics rendering. Dedicated accelerators such as TPUs and NPUs exemplify specialized coprocessors designed for specific domains.

Implementation varies: some coprocessors are external devices connected via interfaces such as PCIe or memory buses, while others are integrated on the same chip as the CPU or within system-on-a-chip designs. Programming models and compiler support are crucial, since data transfer and synchronization between the main processor and the coprocessor can become bottlenecks. As workloads evolve, the role of coprocessors remains to provide targeted performance improvements while keeping the general-purpose CPU uncluttered.