Computer systems that cannot be programmed by the user because they are preprogrammed for a specific task and are buried within the equipment they serve. The term derives from the military, where computer systems are generally activated by the flip of a switch or the push of a button. The continual increase in the densities of ever-smaller microprocessors, on silicon chips that fit on a thumbnail, and the attendant decreases in their costs, has pushed the concept of embedded systems well beyond the original military applications. Embedded systems are also used in industrial, automotive, consumer, and medical applications.
Most embedded microprocessors are of the CISC (complex-instruction-set computer) type, and most of these are used in applications where low cost is paramount and performance is secondary, such as consumer products. The later-generation microprocessors have wider bus widths, up to 64 bits, and thus can do more computations.
Since about 1990, microprocessors of the RISC (reduced-instruction-set computer) type have appeared, with much greater computational capability and at greater cost. RISC processors are used mostly in those embedded applications where performance is primary and low cost is secondary. They are used in engineering workstations, where the computational burdens of high-resolution graphics require such processors. See Computer-aided engineering, Computer graphics, Computer systems architecture