Note: Many topics at this site are reduced versions of the text in "The Encyclopedia of Networking and Telecommunications." Search results will not be as extensive as a search of the book's CD-ROM.

An embedded system is a system within a larger system. It is often implemented on a single integrated circuit or as scaled-down software code. An embedded system typically has a specialized function with programs stored on ROM. Examples of embedded systems are chips that monitor automobile functions, including engine controls, antilock brakes, air bags, active suspension systems, environmental systems, security systems, and entertainment systems. Everything needed for those functions is custom designed into specific chips. No external operating system is required.

Another example is a chip for a microwave oven. It is specifically designed to run the front-panel controls and all the timing and electronics of the oven.

Network managers will need to manage more and more embedded systems devices, ranging from printers to scanners, to handheld computing devices, to cell phones. All of these have a need to connect with other devices, either directly or through a wireless or direct-connect network. Most will have custom operating systems or variations of existing operating systems (e.g., Microsoft Windows CE).

It's easy to picture nearly every electronic device as having an embedded system. For example, refrigerators, washing machines, and even coffee brewers will benefit in some way from embedded systems. A critical feature of an embedded system is its ability to communicate, so embedded systems support Ethernet, Bluetooth (wireless), infrared, or other technologies.

A weather station on top of a building may employ an embedded system that gathers information from external sensors. This information can be pushed or pulled. In the push scenario, the data is automatically sent to devices that have requested it. In the pull scenario, users or network devices access the weather station to read the latest information.

If the weather station is connected to the Internet, it may have its own IP address and, ideally, will provide information to anyone that accesses the IP address. In this sense, the weather station is acting as a mini-Web server. In fact, many embedded systems are basically Web servers on a chip. The chips contain HTTP and HTML functions, and custom applications appropriate for the environment in which the chip will be used.

An interesting 3Com paper called "Massively Distributed Systems" by Dan Nessett discusses the growth of distributed computer networks with billions of new nodes, many of which will be embedded systems. While these embedded systems handle some computing and communication tasks on their own, many will need to off-load heavy computations to more capable systems. The paper discusses the potential architecture of distributed systems that include such embedded system devices. The paper is at the Web site listed on the related entries page.

Another useful Web site is eg3.com, which is the oldest and largest Web resource devoted to electronic design, specifically embedded systems, real time, and DSP. The Web site is at http://www.eg3.com/.