- Embedded computers are the most prevalent form of computers in existence. These devices are found everywhere, from car engines and manufacturing robots to VCRs and microwave ovens. They tend to have very specific tasks.
- The systems they run on are usually primitive, and so the OSs provide limited features. Usually, they have little or no user interface, preferring to spend their time monitoring and managing hardware devices, such as
automobile engines and robotic arms.
- Embedded systems almost always run real-time OSs. A real-time system is used when rigid time requirements (time critical) have been placed on the operation of a processor or the flow of data; thus, it is often used as a control device in a dedicated application.
- A real-time system has well-defined, fixed time constraints. Processing must be done within the defined constraints, or the system will fail. Real-Time systems may be either;
- hard (must react in time), the real-time system absolutely must complete critical tasks within a guaranteed time.
- Contrast this system with a time-sharing system, where it is desirable (but not mandatory) to respond quickly, or a batch system, which may have no time constraints at all.
- soft real-time (deal with failure to react in time), the real-time system can satisfy its performance criteria by running any critical task at a higher priority (of CPU access).
- Useful in applications (multimedia, virtual reality) requiring advanced operating-system features.
Cem Ozdogan
2011-02-14
