Embedded Systems

    An Embedded System is a computer system designed to do one or a few dedicated and/or specific functions. often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. By contrast, a general-purpose computer, such as a personal computer (PC), is designed to be flexible and to meet a wide range of end-user needs. Embedded systems control many devices in common use today.

• Never meant to be traditional, general purpose computers.
• Examples: mobile phones, home multimedia, network appliances, transportation or industrial control..
• Use a general purpose processor (most popular ones: arm, x86, ppc) or even a much simpler microcontroller. 

    Physically, embedded systems range from portable devices such as digital watches and MP3 players, to large stationary installations like traffic lights, factory controllers, or the systems controlling nuclear power plants. Complexity varies from low, with a single microcontroller chip, to very high with multiple units, peripherals and networks mounted inside a large chassis or enclosure.
 

Architecture: A general purpose computer has four main sections: The arithmetic and logic unit (ALU), the control unit, the  memory and the input and output devices (I/O). These parts are interconnected by busses. The control unit, ALU, registers, basic I/O and often other hardware closely linked with these are known as a central processing unit. Early CPUs were comprised of many separate components but since the mid-1970s CPUs have typically been constructed on a single integrated circuit called a microprocessor.

Architecture