An embedded system is
|“||[a] system that performs or controls a function, either in whole or in part, as an integral element of a larger system or subsystem.||”|
An embedded system may be thought of as a special-purpose computer system, which is completely encapsulated by the device it controls. It is often designed to perform dedicated functions and subject to resource-limitation constraints as part of a mechanical device.
Often embedded system programs are implemented in read-only memory and are not intended to be generally reprogrammable. (In contrast, general-purpose computing systems, such as PCs, execute a wide variety of functions and are easily reprogrammed.) Most embedded systems use a mix of various firmware items that supplement the software running on the volatile memory portion of the system.
- Technology Assessment: Cybersecurity for Critical Infrastructure Protection, at 141.
- Department of Defense, National Computer Security Center, Glossary of Computer Security Terms (NCSC-TG-004, Ver. 1) (Oct. 21, 1988).