An embedded system is a combination of two distinct words i.e. embedded+ system. The meaning of embedded is assemble or attached various components into a single unit while a system is an arrangement of predefined set of rules in which all assembled units work together to organizing one or two specific tasks.
There are various definitions to define embedded system but the best way to understand the real meaning or to define it is to describe it in terms of what it is not and with examples of how it is used.
An embedded system is a microprocessor-based system that is built to control a function or range of functions and is not designed to be programmed by the end user in the same way that a personal computer (PC) or General Purpose Computer is. Yes, a user of the system can make choices concerning preinstalled functionality but cannot change the functionality of the system by adding/replacing software. In addition embedded system is any device that includes computer system to perform a specific task, but is not itself a general purpose computer. With a personal computer, this is exactly what a user can do: one minute the personal computer is a word processor, in another minute it’s a audio/video operator and the next it’s a games machine simply by changing the software.
An embedded system is designed to complete one specific task albeit with choices and different options. The last point is important because it differentiates itself from the world of the PC where the end user does reprogram it whenever a different software package is bought and run. However, PCs have offered an easily accessible source of hardware and software for embedded systems and it should be no surprise that they form the root of many embedded systems.
In short an embedded system has hardware as well as software and it is a division of a larger system and is expected to function without human involvement. An embedded system is expected to, expected to respond, monitor as well as control external environment using sensors and actuators. So, basically embedding a computer into an appliance and the computer is not expected to be used as general purpose computing becomes an embedded system.
Examples of embedded system:
Personal digital assistance: It is also called handhelds or palmtops device. It is an embedded system that designed to manage user personal information, such as contents, appointments, and to-do lists, today’s devices can also connect to the internet, act as global positioning system (GPS) devices and run multimedia software.
Printers: A printer an embedded system designed for a specific task that accepts text and graphics output from a compute and transfers the information on to paper.
Cell phone: A cell phone is a portable telephone embedded system which uses cellular network technology to make and receive calls.
Television: It is a system for converting visual images (with sound) into electrical signals, spreading them by radio or other means, and displaying them electronically on a screen.
Geyser: Geyser is a hot spring in which water intermittently boils, sending a tall column of water and steam into the air.
Biometric systems: A biometric system is an embedded system technology that uses uniquely identified information about a person (or other biological organism) to identify that person.
Surveillance system: A surveillance system is one another embedded system which is capable of capturing images and videos that can be compressed, stored or sent over communication networks.
Microwave oven: A microwave oven is an embedded system that uses as a kitchen appliance. It is used to heats and cooks food by exposing it to microwave radiation in the electromagnetic spectrum.