microprocessor

A microprocessor is the central processing unit (CPU) of a computer implemented on a single integrated circuit. It contains the core CPU components—an arithmetic logic unit, control unit, and registers—and executes instructions fetched from memory. In a typical system, the microprocessor works with separate memory and input/output circuitry, forming a microcomputer system. By contrast, microcontrollers integrate memory and I/O on the same chip, combining processing with control functions for embedded applications.

The first commercial microprocessors appeared in the early 1970s, led by Intel's 4004. Subsequent generations expanded from 8-bit designs such as the 8080 and Z80 to 16-bit and 32-bit families, culminating in 64-bit processors that power modern desktops, servers, and mobile devices. Today, major instruction set architectures include x86 (Intel, AMD), ARM, MIPS, PowerPC, and the increasingly influential RISC-V.

Architectural design centers on the instruction set architecture (ISA), which defines supported operations, and the microarchitecture, which implements the ISA in hardware. Designs are associated with CISC or RISC philosophies, though modern CPUs blend aspects of both. Techniques such as pipelining, out-of-order execution, caches, and branch prediction improve instruction throughput. Many contemporary processors are multicore and may include specialized accelerators for graphics, vector processing, or artificial intelligence workloads. Most CPUs adhere to a von Neumann or modified von Neumann model with hierarchical memory systems, while some architectural concepts draw on Harvard-style separations within caches or on-chip components.

Manufacturing advances using CMOS technology have driven growth in transistor counts and performance, while power and heat dissipation constrain progress. The microprocessor remains central to computing, enabling general-purpose computation, embedded control, and a wide range of consumer and industrial applications.