Definition: embedded system

Any electronic system that uses a computer chip but is not a general-purpose desktop or laptop computer, tablet or smartphone. Embedded systems use microcontrollers (MCUs), microprocessors (MPUs) or custom-designed chips as their processing component (see ASIC). Also called an "embedded device," billions are used every year in home and industrial products. See microprocessor and microcontroller.

Embedded systems are employed in cars, planes, trains, space vehicles, machine tools, cameras, consumer electronics, office appliances, network appliances, GPS navigation as well as robots and toys. Low-cost consumer products can use microcontroller chips that cost less than a dollar.

The First Embedded Systems
Although not general-purpose processors, the first embedded systems used discrete electronic components for missle guidance and space missions in the mid-1960s. Volkswagen designed the first electronic fuel injection system in the late-1960s.

Embedded Devices Are Special Purpose
A major difference between embedded systems and general-purpose computing is that the embedded processor performs only one or a handful of related functions such as controlling the cycles in a washing machine or the cruise control in a vehicle. A microcontroller's task can be as simple as turning a light on and off.

All Operating Systems or None
There are embedded versions of Linux, Windows and Mac, as well as other specialized operating systems. Embedded systems typically have limited storage, and an embedded OS often works with much less memory (RAM) than a desktop OS. They also typically work in real time.

Small embedded systems may not even require an operating system because there is often no need to multitask or manage simultaneous inputs and outputs, the primary tasks of an OS.

Programs Are in Firmware
The software in embedded systems resides permanently in firmware, such as flash memory or read-only memory in contrast to a general-purpose computer that loads its instructions into random access memory (RAM) to run a program.

Sometimes, single board and rack mounted general-purpose computers are called "embedded computers" if used to control a single printer, drill press or other such device. See embedded market, smart car, Windows CE, Windows XP Embedded, Embedded Linux and embedded language.

Embedded Systems in a Volvo

By the turn of the century, the Volvo S80 used chips to control 17 functions. Today's cars are electronic systems on wheels that use a thousand or more chips. See microcontroller.

Embedded in a Shoe!

The microprocessor in this sneaker calculates the foot-to-ground pressure and continuously adjusts the comfort level by moving a cushion. (Image courtesy of adidas-Salomon AG.)