A single-board computer (SBC) is a complete computer built on a single

circuit board A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a laminated sandwich struc ...

, with

microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circ ...

(s),

memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered ...

input/output In computing, input/output (I/O, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, possibly a human or another information processing system. Inputs are the signals ...

(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 computer A portable computer is a computer designed to be easily moved from one place to another and included a display and keyboard together, with a single plug, much like later desktop computers called '' all-in-ones'' (AIO), that integrate the s ...

s integrate all their functions onto a single printed circuit board. Unlike a desktop

personal computer A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...

, single board computers often do not rely on

expansion slot Expansion may refer to: Arts, entertainment and media * '' L'Expansion'', a French monthly business magazine * ''Expansion'' (album), by American jazz pianist Dave Burrell, released in 2004 * ''Expansions'' (McCoy Tyner album), 1970 * ''Expansi ...

s for peripheral functions or expansion. Single board computers have been built using a wide range of

s. Simple designs, such as those built by computer hobbyists, often use static RAM and low-cost 32- or 64-bit processors like

ARM In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between th ...

. Other types, such as blade servers, would perform similar to a

server Server may refer to: Computing *Server (computing), a computer program or a device that provides functionality for other programs or devices, called clients Role * Waiting staff, those who work at a restaurant or a bar attending customers and su ...

computer, only in a more compact format. A

computer-on-module A computer-on-module (COM) is a type of single-board computer (SBC), a subtype of an embedded computer system. An extension of the concept of system on chip (SoC) and system in package (SiP), COM lies between a full-up computer and a microcontro ...

is a type of single-board computer made to plug into a carrier board, baseboard, or

backplane A backplane (or "backplane system") is a group of electrical connectors in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. It is used as a back ...

for system expansion.

History

The first true single-board computer (see the May 1976 issue of ''

Radio-Electronics ''Radio-Electronics'' was an American electronics magazine that was published under various titles from 1929 to 2003. Hugo Gernsback, sometimes called the father of science fiction, started it as ''Radio-Craft'' in July 1929. The title was changed ...

'') called the "dyna-micro" was based on the Intel C

8080 The Intel 8080 (''"eighty-eighty"'') is the second 8-bit microprocessor designed and manufactured by Intel. It first appeared in April 1974 and is an extended and enhanced variant of the earlier 8008 design, although without binary compatibil ...

A, and also used Intel's first

EPROM An EPROM (rarely EROM), or erasable programmable read-only memory, is a type of programmable read-only memory (PROM) chip that retains its data when its power supply is switched off. Computer memory that can retrieve stored data after a power s ...

, the C1702A. The dyna-micro was re-branded b
E&L Instruments
of Derby, Connecticut, in 1976 as the

(Mini-Micro Designer 1) and was made famous as the example microcomputer in the very popular 8080

series of the time. SBCs also figured heavily in the early history of home computers, for example in the

Acorn Electron The Acorn Electron (nicknamed the Elk inside Acorn and beyond) was a lower-cost alternative to the BBC Micro educational/ home computer, also developed by Acorn Computers Ltd, to provide many of the features of that more expensive machine at a ...

and the

BBC Micro The British Broadcasting Corporation Microcomputer System, or BBC Micro, is a series of microcomputers and associated peripherals designed and built by Acorn Computers in the 1980s for the BBC Computer Literacy Project. Designed with an emphas ...

. Other typical early single board computers like the

KIM-1 The KIM-1, short for ''Keyboard Input Monitor'', is a small 6502-based single-board computer developed and produced by MOS Technology, Inc. and launched in 1976. It was very successful in that period, due to its low price (thanks to the inexp ...

were often shipped without

enclosure Enclosure or Inclosure is a term, used in English landownership, that refers to the appropriation of "waste" or " common land" enclosing it and by doing so depriving commoners of their rights of access and privilege. Agreements to enclose land ...

, which had to be added by the owner. Other early examples are the

Ferguson Big Board The Big Board (1980) and Big Board II (1982) were Z80 based single-board computers designed by Jim Ferguson. They provided a complete CP/M compatible computer system on a single printed circuit board, including CPU, memory, disk drive interface, ...

, the Ampro Little Board, and the

Nascom The Nascom 1 and 2 were single-board computer kits issued in the United Kingdom in 1977 and 1979, respectively, based on the Zilog Z80 and including a keyboard and video interface, a serial port that could be used to store data on a tape cassette ...

. As the PC market became more prevalent, fewer SBCs were being used in computers. The main components were assembled on a motherboard, and peripheral components such as hard disk drive controllers and graphics processors were located on

daughterboard In computing, an expansion card (also called an expansion board, adapter card, peripheral card or accessory card) is a printed circuit board that can be inserted into an electrical connector, or expansion slot (also referred to as a bus s ...

s. The recent availability of advanced chipsets providing most of the I/O features as embedded components allows motherboard manufacturers to offer motherboards with I/O traditionally provided by daughterboards. Most PC motherboards now offer on-board support for disk drives including IDE,

SATA SATA (Serial AT Attachment) is a computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives, optical drives, and solid-state drives. Serial ATA succeeded the earlier Parallel ATA (PATA) standard t ...

NVMe NVM Express (NVMe) or Non-Volatile Memory Host Controller Interface Specification (NVMHCIS) is an open, logical-device interface specification for accessing a computer's non-volatile storage media usually attached via PCI Express (PCIe) bus. The ...

RAID Raid, RAID or Raids may refer to: Attack * Raid (military), a sudden attack behind the enemy's lines without the intention of holding ground * Corporate raid, a type of hostile takeover in business * Panty raid, a prankish raid by male college ...

, integrated

GPU A graphics processing unit (GPU) is a specialized electronic circuit designed to manipulate and alter memory to accelerate the creation of images in a frame buffer intended for output to a display device. GPUs are used in embedded systems, mobi ...

Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1 ...

, and traditional I/O such as

serial port In computing, a serial port is a serial communication interface through which information transfers in or out sequentially one bit at a time. This is in contrast to a parallel port, which communicates multiple bits simultaneously in parallel. ...

and parallel port,

USB Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...

, and keyboard/mouse support. Plug-in cards are now more commonly high performance graphics cards (really graphics co-processors), high-end

RAID controller A disk array controller is a device that manages the physical disk drives and presents them to the computer as logical units. It almost always implements hardware RAID, thus it is sometimes referred to as RAID controller. It also often provides a ...

s, and specialized I/O cards such as

data acquisition Data acquisition is the process of sampling signals that measure real-world physical conditions and converting the resulting samples into digital numeric values that can be manipulated by a computer. Data acquisition systems, abbreviated by the acro ...

and DSP (Digital Signal Processor) boards.

Applications

Single board computers were made possible by increasing the density of integrated circuits. A single-board configuration reduces a system's overall cost, by reducing the number of circuit boards required, and by eliminating connectors and bus driver circuits that would otherwise be used. By putting all the functions on one board, a smaller overall system can be obtained, for example, as in notebook computers. Connectors are a frequent source of reliability problems, so a single-board system eliminates these problems. Single board computers are now commonly defined across two distinct architectures: no slots and slot support. Embedded SBCs are units providing all the required I/O with no provision for plug-in cards. Applications are typically gaming (slot machines, video poker), kiosk, and machine control

automation Automation describes a wide range of technologies that reduce human intervention in processes, namely by predetermining decision criteria, subprocess relationships, and related actions, as well as embodying those predeterminations in machines ...

. Embedded SBCs are much smaller than the ATX-type motherboard found in PCs, and provide an I/O mix more targeted to an industrial application, such as on-board digital and analog I/O, on-board bootable flash memory (eliminating the need for a

disk drive Disk storage (also sometimes called drive storage) is a general category of storage mechanisms where data is recorded by various electronic, magnetic, optical, or mechanical changes to a surface layer of one or more rotating disks. A disk drive is ...

), no video, etc. The term "Single Board Computer" now generally applies to an architecture where the single board computer is plugged into a

to provide for I/O cards. In the case of

PC104 PC/104 (or PC104) is a family of embedded computer standards which define both form factors and computer buses by the PC/104 Consortium. Its name derives from the 104 pins on the interboard connector ( ISA) in the original PC/104 specificatio ...

, the bus is not a backplane in the traditional sense but is a series of pin connectors allowing I/O boards to be stacked. Single board computers are most commonly used in industrial situations where they are used in

rackmount A 19-inch rack is a standardized frame or enclosure for mounting multiple electronic equipment modules. Each module has a front panel that is wide. The 19 inch dimension includes the edges or "ears" that protrude from each side of the equ ...

format for process control or embedded within other devices to provide control and interfacing. They are used in deep-sea exploration on the ALICE deep sea probes and in outer space, on the Ariane and Pegasus rockets and

Space Shuttle The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program ...

. Because of the very high levels of integration, reduced component counts and reduced connector counts, SBCs are often smaller, lighter, more power efficient and more reliable than comparable multi-board computers. The primary advantage of an ATX motherboard as compared to an SBC is cost. Motherboards are manufactured by the millions for the consumer and office markets allowing tremendous

economies of scale In microeconomics, economies of scale are the cost advantages that enterprises obtain due to their scale of operation, and are typically measured by the amount of output produced per unit of time. A decrease in cost per unit of output enables ...

. Single-board computers are a market niche and are manufactured less often and at a higher cost. Motherboards and SBCs now offer similar levels of feature integration meaning that a motherboard failure in either standard will require equivalent replacement.

Types, standards

One common variety of single board computer uses standardized

computer form factor Form factor is a hardware design aspect that defines and prescribes the size, shape, and other physical specifications of components, particularly in electronics. A form factor may represent a broad class of similarly sized components, or it may ...

s intended for use in a

enclosure. Some of these types are

CompactPCI CompactPCI is a computer bus interconnect for industrial computers, combining a Eurocard-type connector and PCI signaling and protocols. Boards are standardized to 3 U or 6U sizes, and are typically interconnected via a passive backplane. The ...

, PXI,

VMEbus VMEbus (Versa Module Europa or Versa Module Eurocard bus) is a computer bus standard, originally developed for the Motorola 68000 line of CPUs, but later widely used for many applications and standardized by the IEC as ANSI/IEEE 1014-1987. ...

, VXI, and

PICMG PICMG, or PCI Industrial Computer Manufacturers Group, is a consortium of over 140 companies. Founded in 1994, the group was originally formed to adapt Conventional PCI, PCI technology for use in high-performance telecommunications, military, an ...

. SBCs have been built around various internal processing structures including the Intel architecture, multiprocessing architectures, and lower power processing systems like RISC and SPARC. In the Intel PC world, the intelligence and interface/control circuitry is placed on a plug-in board that is then inserted into a passive (or active) backplane. The result is similar to having a system built with a motherboard, except that the backplane determines the slot configuration. Backplanes are available with a mix of slots (ISA, PCI, PCI-X, PCI-Express, etc.), usually totaling 20 or fewer, meaning it will fit in a 19" rackmount enclosure (17" wide chassis). Some single-board computers have connectors that allow a stack of circuit boards, each containing expansion hardware, to be assembled without a traditional backplane. Examples of stacking SBC form factors include PC/104, PC/104-''Plus'',

PCI-104 PC/104 (or PC104) is a family of embedded computer standards which define both form factors and computer buses by the PC/104 Consortium. Its name derives from the 104 pins on the interboard connector ( ISA) in the original PC/104 specificati ...

, EPIC, and EBX; these systems are commonly available for use in embedded control systems. Stack-type SBCs often have memory provided on plug-cards such as

SIMM A SIMM (single in-line memory module) is a type of memory module containing random-access memory used in computers from the early 1980s to the early 2000s. It differs from a dual in-line memory module (DIMM), the most predominant form of memory ...

s and

DIMM A DIMM () (Dual In-line Memory Module), commonly called a RAM stick, comprises a series of dynamic random-access memory integrated circuits. These memory modules are mounted on a printed circuit board and designed for use in personal computers ...

Hard drive A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magne ...

circuit boards are also not counted for determining if a computer is an SBC or not for two reasons, firstly because the HDD is regarded as a single block storage unit, and secondly because the SBC may not require a hard drive at all as most can be booted from their network connections.

Form factors

* AdvancedTCA *

* Embedded Compact Extended (ECX) *

Mini-ITX Mini-ITX is a motherboard form-factor, developed by VIA Technologies in 2001. They are commonly used in small-configured computer systems. Originally, they were a niche product, designed for fan-less cooling with a low power consumption archi ...

Multibus Multibus is a computer bus standard used in industrial systems. It was developed by Intel Corporation and was adopted as the IEEE 796 bus. The Multibus specification was important because it was a robust, well-thought out industry standard with ...

* PC/104 *

Pico-ITX In computer design, Pico-ITX is a PC motherboard form factor announced by VIA Technologies in January 2007 and demonstrated later the same year at CeBIT. The formfactor was transferred over to SFF-SIG in 2008. The Pico-ITX form factor specificatio ...

* PXI *

Qseven Qseven, a computer-on-module (COM) form factor, is a small, highly integrated computer module that can be used in a design application much like an integrated circuit component. It is smaller than other computer-on-module standards such as COM E ...

VPX VPX (Virtual Path Cross-Connect), also known as VITA 46, refers to a set of standards for connecting components of a computer (known as a computer bus), commonly used by defense contractors. Some are ANSI standards such as ANSI/VITA 46.0–2019. ...

* VXI *

96Boards Linaro is an engineering organization that works on free and open-source software such as the Linux kernel, the GNU Compiler Collection (GCC), QEMU, power management, graphics and multimedia interfaces for the ARM family of instruction sets and ...

(CE, EE, EETV and IE)

References

{{Authority control Microcomputers

History

Applications

Types, standards

Form factors

See also

References