An embedded system is some combination of computer hardware and software, either fixed in capability or programmable, that is specifically designed for a particular function.
Embedded systems are commonly found in consumer, cooking, industrial, automotive, medical, commercial and military applications.
Embedded systems serve a single purpose and utilise a microcontroller or DSP chip to carry out instructions – Often they are hidden in devices where it might not be apparent that any computing is taking place. Microcontrollers are programmed and where the programming may need to be flexible, the code may reside on a removable chip or memory card. Every microcontroller has its own instruction set.
Modern embedded systems are often based on microcontrollers but ordinary microprocessors 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 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).(Wikipedia, 2016)
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 the reliability and performance. Some embedded systems are mass-produced, benefiting from economies of scale.
Embedded systems are not always standalone devices. Many embedded systems consist of small parts within a larger device that serves a more general purpose.
The program instructions written for embedded systems are referred to as firmware, and are stored in read-only memory or Flash memory chips. They run with limited computer hardware resources: little memory, small or non-existent keyboard or screen. (Barr, Massa and Barr, 2006)
Barr, M., Massa, A. and Barr, M. (2006). Programming embedded systems. Sebastopol, Calif.: O’Reilly.
Wikipedia. (2016). Embedded system. [online] Available at: https://en.wikipedia.org/wiki/Embedded_system.