A single-board computer (SBC) is a complete computer built on a single printed circuit board, integrating the processor, memory, storage interfaces, and input/output onto one piece of hardware rather than spreading them across a backplane of plug-in cards. Where a traditional computer might use a motherboard plus separate expansion cards for memory and peripherals, an SBC puts everything needed to boot and run an operating system in one compact unit. The Raspberry Pi documentation captures the modern flavor of the idea when it describes the machine as “a compact computer” usable either as a desktop or as a headless system.
The concept dates to the 1970s, when microprocessors made it possible to fit a usable computer onto a small board. Early single-board computers were often microprocessor trainer and evaluation boards: spartan machines with a hex keypad, a few digits of LED display, and a small amount of memory, sold so that engineers and students could learn to program a particular processor. These boards were complete computers in the strict sense, even if they had no operating system and were programmed at a very low level, and they established the basic SBC pattern of CPU, memory, and I/O on one board.
It is useful to distinguish single-board computers from microcontroller boards, because the line is often blurred. A microcontroller board such as an Arduino centers on a microcontroller, a chip with CPU, memory, and peripherals integrated for embedded control, and typically runs a single program directly on the hardware with no operating system. A single-board computer in the fuller modern sense, by contrast, runs a general-purpose operating system, supports a desktop or multitasking environment, and is meant for general computing. The Raspberry Pi sits clearly on the SBC side: it boots a Linux operating system and behaves like a real computer, while also exposing a GPIO header for hardware projects.
The Raspberry Pi made the modern single-board computer a household idea by combining the form factor with a very low price and a full Linux software stack. Its documentation describes a family that spans “single-board computers, Zero variants, keyboard computers, Compute Modules, and Pico microcontrollers,” illustrating how one product line can straddle both the SBC and microcontroller categories. The 40-pin GPIO header lets these boards interface directly with sensors and actuators, blending the general-purpose computer with the embedded-hardware role.
The single-board computer’s importance is that it packages an entire computer into something small, cheap, and easy to embed, which is exactly what is needed for teaching, prototyping, robotics, media devices, servers, and the Internet of Things. From 1970s trainer boards to the Raspberry Pi and its many competitors, the SBC has been the bridge between full desktop computers and tiny embedded microcontrollers, offering real operating systems and general-purpose power in a form factor small enough to build into almost anything.