Single-board computer

A single-board computer (SBC) is a complete computer built on a single circuit board, with microprocessor(s), memory, input/output (I/O) and other features required of a functional computer. Single-board computers are commonly made as demonstration or development systems, for educational systems, or for use as embedded computer controllers. Many types of home computers or portable computers integrate all their functions onto a single printed circuit board.

Unlike a desktop personal computer, single-board computers often do not rely on expansion slots for peripheral functions or expansion. Single-board computers have been built using a wide range of microprocessors. Simple designs, such as those built by computer hobbyists, often use static RAM and low-cost 32- or 64-bit processors like ARM. Other types, such as blade servers, would perform similar to a server computer, only in a more compact format.

A computer-on-module is a type of single-board computer made to plug into a carrier board, baseboard, or backplane for system expansion.

The first true single-board computer was based on the Intel C8080A, also using Intel's first EPROM, the C1702A. Schematics for the machine, called the "dyna-micro" were published in Radio-Electronics magazine in May 1976. Later that year, production of the system began by E&L Instruments, a Derby, Connecticut-based computer manufacturer, which branded the system as the "Mini Micro Designer 1", intending it for use as a programmable microcontroller for prototyping electronic products. The MMD-1 was made famous as an example microcomputer in popular 8080 instruction series of the time.

Early SBCs figured heavily in the early history of home computers, such as the Acorn Electron and the BBC Micro, also developed by Acorn. Other typical early single-board computers like the KIM-1 were often shipped without enclosure, which had to be added by the owner. Other early examples are the Ferguson Big Board, the Ampro Little Board, and the Nascom. Many home computers in the 1980s were single-board computers, with some even encouraging owners to solder upgraded components directly to pre-marked points on the board.

As the PC became more prevalent, SBCs decreased in market share due to their low extensibility. The rapid adoption of IBM's standards for peripherals and the standardization of the PCI bus in the 1990s made motherboards and compatible components and peripherals cheap and ubiquitous, while the development of multimedia platforms such as the CD-ROM and Sound Blaster cards had begun to fast outpace the rate at which users needed to replace their personal computers. These two trends disincentivized single-board computers, and instead encouraged the proliferation of motherboards, which typically housed the CPU and other core components, with peripheral components such as hard disk drive controllers and graphics processors, and even some core components such as RAM modules, located on daughterboards.

Computers began to move back towards fewer boards in the 2000s. As new standards like USB dramatically reduced the variety of peripheral standards motherboards were expected to support, advances in integrated circuit manufacturing provided new chipsets which could provide the functionality of many daughterboards, particularly I/O, in a single chip. By the end of the decade, PC motherboards offered on-board support for disk drives including IDE, SATA, NVMe, RAID, integrated GPU, Ethernet, and traditional I/O such as serial port and parallel port, USB, and keyboard/mouse support. Plug-in "cards" retained their importance as high performance components, such as physically large and complex graphics coprocessors, high-end RAID controllers, and specialized I/O cards such as data acquisition and DSP boards.

The 2010s were defined by rapid and sustained growth in single-board computers, enabled largely by advances in integrated circuit production techniques that made it possible for the first time to include most or all of the core components of a motherboard on a single integrated circuit die. One of the more well known single-board-computers of the decade was the Raspberry Pi, which was built around a custom Broadcom SoC with open-source drivers. Originally intended for education, the Raspberry Pi contained a number of features, such as optimized Linux support and programmable GPIO pins, that were also greatly appealing to hobbyists, who used the Pi, and other comparable SBCs, for projects such as home automation, video game emulation, media streaming, and other experimentation. In industry, the rapid growth of smartphones and other small-scale devices encouraged hardware manufacturers to move towards more frequent use of SoCs and the reduction of motherboards in size, extensibility and complexity, while the proliferation of the Internet of Things increased demand for small, cheap components that would allow unconventional devices to access the Internet. Both of these factors dramatically increased production of single-board computers throughout the decade.