Any electronic system that uses a computer chip, but that is not a general-purpose workstation, desktop or laptop computer. Such systems use microcontrollers (MCUs) or microprocessors (MPUs), or they may use custom-designed chips. Deployed by the billions each year in myriad applications, the embedded systems market uses the lion's share of all the electronic components in the world.
Embedded systems are employed in automobiles, planes, trains, space vehicles, machine tools, cameras, consumer electronics, office appliances, network appliances, video games, cellphones, PDAs, GPS navigation as well as robots and toys. Low-cost consumer products can use microcontroller chips that cost less than a dollar. See microprocessor and microcontroller.
All Kinds of Operating Systems
There are embedded versions of Linux, Windows and Mac, as well as other commercial and proprietary operating systems specialized for embedded systems. Embedded systems typically have limited storage, and an embedded OS is often designed to work in much less memory than desktop operating systems. They also typically work in real time. Small embedded systems may run an application that contains its own input/output routines and not require a separate operating system.
Programs Are in Firmware
In embedded systems, the software typically resides in firmware, such as a flash memory or read-only memory (ROM) chip, in contrast to a general-purpose computer that loads its programs into random access memory (RAM) each time.
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.
These are the systems in a 1998 Volvo S80, all of which were linked via two networks and controlled by a central module. Thirty years earlier, the Volkswagen 1600 used a microprocessor to control its fuel injection, making it the first embedded system in the auto industry. Today, a car's electronics cost more than the steel used to build it, and high-end cars can have more than 100 CPUs.
The microprocessor embedded in this adidas running shoe calculates the pressure between the runner's foot and the ground five million times per second and continuously changes the cushioning to match an adjustable comfort level. The computer controls a motor that lengthens and shortens a cable attached to a plastic cushioning element. (Image courtesy of adidas-Salomon AG.)
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