Embedded System:
An embedded system is an engineering artifact involving computation that is subject to physical constraints arising through interactions of computational processes with the physical world. Reaction constraints originate from the behavioral requirements & specify deadlines, throughput and jitter whereas execution constraints originate from the implementation requirements & put bounds on available processor speeds, power, memory and hardware failure rates. The key to embedded systems design is to obtain desired functionality under both kinds of constraints.
Characteristics of Embedded System:
1. Embedded systems are application specific & single functioned, applications is known prior, the programs are executed repeatedly.
2. Efficiency is of paramount importance for embedded system. They are optimized for energy, code size, execution time, weight & dimensions and cost.
3. Embedded systems are typically designed to meet real-time constraints. A real-time system reacts to stimuli from the controlled object/operator within the time interval dictated by the environment. For real-time systems, right answers arriving too late are wrong.
4. It often interact with external world through sensors and actuators and hence are typically reactive systems. A reactive system is in continual interaction with the environment and executes at a pace determined by that environment.
5. They generally have minimal or no user interface.