We read in newspapers that a doctor had successfully transplanted a cardiac pacemaker in his patient’s chest by sitting around 200kilometres away. Also we know about driverless cars that could take us to the destiny by using its inbuilt navigation systems. Embedded microprocessors or micro controllers are the brain behind these.
An embedded system is any device controlled by instructions stored on a chip. These devices are usually controlled by a micro processor that executes the instructions stored on a read only memory(ROM) chip.
The software for the embedded system is called firmware. The firmware will be written in assembly language for time or resource critical operations or using higher level languages like C or embedded C. The software will be simulated using micro code simulators for the target processor. Since they are supposed to perform only specific tasks, these programs are stored in read only memories(ROMs).Moreover they may need no or minimal inputs from the user, hence the user interface like monitor, mouse and large keyboard etc,may be absent.
Embedded systems are computer systems that monitor, respond to, or control an external environment. This environment is connected to the computer system through sensors, actuators, and other input-output interfaces. It may consist of physical or biological objects of any form and structure. Often humans are part of the connected external world, but a wide range of other natural and artificial objects, as well as animals are also possible.
Embedded systems are also known as real time systems since they respond to an input or event and produce the result within a guaranteed time period. This time period can be few microseconds to days or months. The computer system must meet various timing and other constraints that are imposed on it by the real-time behavior of the external world to which it is interfaced. Hence comes the name real time. Another Name for many of these systems is reactive systems, because their primary purpose is to respond to or react to signals from their environment. A real time computer system may be a component of a larger system in which it is embedded; reasonably such a computer component is called an embedded system.