
An embedded system is a
computer system—a combination of a
computer processor,
computer memory
In computing, memory is a device or system that is used to store information for immediate use in a computer or related computer hardware and digital electronic devices. The term ''memory'' is often synonymous with the term '' primary storage ...
, and
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 ...
peripheral devices—that has a dedicated function within a larger mechanical or
electronic system.
It is ''embedded'' as part of a complete device often including electrical or electronic hardware and mechanical parts.
Because an embedded system typically controls physical operations of the machine that it is embedded within, it often has
real-time computing constraints. Embedded systems control many devices in common use today.
, it was estimated that ninety-eight percent of all microprocessors manufactured were used in embedded systems.
Modern embedded systems are often based on
microcontrollers (i.e. microprocessors with integrated memory and peripheral interfaces), but ordinary microprocessors (using external chips for memory and peripheral interface circuits) are also common, especially in more complex systems. In either case, the processor(s) used may be types ranging from general purpose to those specialized in a certain class of computations, or even custom designed for the application at hand. A common standard class of dedicated processors is the
digital signal processor (DSP).
Since the embedded system is dedicated to specific tasks,
design engineers can optimize it to reduce the size and cost of the product and increase its reliability and performance. Some embedded systems are mass-produced, benefiting from
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 a ...
.
Embedded systems range in size from portable personal devices such as
digital watches and
MP3 players to bigger machines like
home appliances, industrial
assembly lines
An assembly line is a manufacturing process (often called a ''progressive assembly'') in which parts (usually interchangeable parts) are added as the semi-finished assembly moves from workstation to workstation where the parts are added in seq ...
,
robots, transport vehicles,
traffic light controllers, and
medical imaging systems. Often they constitute subsystems of other machines like
avionics in
aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines. ...
and
astrionics in
spacecraft
A spacecraft is a vehicle or machine designed to spaceflight, fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including Telecommunications, communications, Earth observation satellite, Earth ...
. Large installations like
factories,
pipelines and
electrical grids rely on multiple embedded systems networked together. Generalized through software customization, embedded systems such as
programmable logic controllers frequently comprise their functional units.
Embedded systems range from those low in complexity, with a single microcontroller chip, to very high with multiple units,
peripherals and networks, which may reside in
equipment racks or across large geographical areas connected via long-distance communications lines.
History
Background
The origins of the microprocessor and the microcontroller can be traced back to the
MOS integrated circuit, which is an
integrated circuit chip
fabricated from
MOSFETs (metal-oxide-semiconductor
field-effect transistors) and was developed in the early 1960s. By 1964, MOS chips had reached higher
transistor density
The transistor count is the number of transistors in an electronic device (typically on a single substrate or "chip"). It is the most common measure of integrated circuit complexity (although the majority of transistors in modern microprocessors ...
and lower manufacturing costs than
bipolar
Bipolar may refer to:
Astronomy
* Bipolar nebula, a distinctive nebular formation
* Bipolar outflow, two continuous flows of gas from the poles of a star
Mathematics
* Bipolar coordinates, a two-dimensional orthogonal coordinate system
* Bipolar ...
chips. MOS chips further increased in complexity at a rate predicted by
Moore's law, leading to
large-scale integration (LSI) with hundreds of
transistors on a single MOS chip by the late 1960s. The application of MOS LSI chips to
computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...
was the basis for the first microprocessors, as engineers began recognizing that a complete
computer processor system could be contained on several MOS LSI chips.
The first multi-chip microprocessors, the
Four-Phase Systems AL1 in 1969 and the
Garrett AiResearch MP944 in 1970, were developed with multiple MOS LSI chips. The first single-chip microprocessor was the
Intel 4004, released in 1971. It was developed by
Federico Faggin, using his
silicon-gate MOS technology, along with
Intel
Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California, Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the devel ...
engineers
Marcian Hoff and
Stan Mazor
Stanley Mazor is an American microelectronics engineer who was born on 22 October 1941 in Chicago, Illinois. He is one of the co-inventors of the world's first microprocessor architecture, the Intel 4004, together with Ted Hoff, Masatoshi Shima ...
, and
Busicom engineer
Masatoshi Shima.
Development
One of the first recognizably modern embedded systems was the
Apollo Guidance Computer, developed ca. 1965 by
Charles Stark Draper
Charles Stark "Doc" Draper (October 2, 1901 – July 25, 1987) was an American scientist and engineer, known as the "father of inertial navigation". He was the founder and director of the Massachusetts Institute of Technology's Instrumen ...
at the
MIT Instrumentation Laboratory. At the project's inception, the Apollo guidance computer was considered the riskiest item in the Apollo project as it employed the then newly developed
monolithic integrated circuits to reduce the computer's size and weight.
An early mass-produced embedded system was the
Autonetics D-17 guidance computer for the
Minuteman missile, released in 1961. When the Minuteman II went into production in 1966, the D-17 was replaced with a new computer that represented the first high-volume use of integrated circuits.
Since these early applications in the 1960s, embedded systems have come down in price and there has been a dramatic rise in processing power and functionality. An early microprocessor, the
Intel 4004 (released in 1971), was designed for
calculators and other small systems but still required external memory and support chips. By the early 1980s, memory, input and output system components had been integrated into the same chip as the processor forming a microcontroller. Microcontrollers find applications where a general-purpose computer would be too costly. As the cost of microprocessors and microcontrollers fell, the prevalence of embedded systems increased.
Today, a comparatively low-cost microcontroller may be programmed to fulfill the same role as a large number of separate components. With microcontrollers, it became feasible to replace, even in consumer products, expensive knob-based
analog
Analog or analogue may refer to:
Computing and electronics
* Analog signal, in which information is encoded in a continuous variable
** Analog device, an apparatus that operates on analog signals
*** Analog electronics, circuits which use analo ...
components such as
potentiometers and
variable capacitors with up/down buttons or knobs read out by a microprocessor. Although in this context an embedded system is usually more complex than a traditional solution, most of the complexity is contained within the microcontroller itself. Very few additional components may be needed and most of the design effort is in the software. Software prototype and test can be quicker compared with the design and construction of a new circuit not using an embedded processor.
Applications

Embedded systems are commonly found in consumer, industrial,
automotive,
home appliances, medical, telecommunication, commercial, aerospace and military applications.
Telecommunication
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than tha ...
s systems employ numerous embedded systems from
telephone switches for the network to
cell phones at the
end user. Computer networking uses dedicated
routers and
network bridges to route data.
Consumer electronics
Consumer electronics or home electronics are Electronics, electronic (Analogue electronics, analog or digital electronics, digital) equipment intended for everyday use, typically in private homes. Consumer electronics include devices used for ...
include
MP3 players,
television set
A television set or television receiver, more commonly called the television, TV, TV set, telly, tele, or tube, is a device that combines a tuner, display, and loudspeakers, for the purpose of viewing and hearing television broadcasts, or using ...
s,
mobile phone
A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive telephone call, calls over a radio freq ...
s,
video game consoles,
digital camera
A digital camera is a camera that captures photographs in digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film. Digital cameras are now widely incorporated into mobile devic ...
s,
GPS receivers, and
printers. Household appliances, such as