Embedded System is: specified purpose controller  which is embedded as part of larger system.

For example, let’s see simple embedded system such as digital clock. Digital clock has microcontroller (the controller) which is embedded to clock system (the larger system). The controller has specific task, to do all necessary  to make the digital clock works.

Microcontroller and Computer:
The Brain of Embedded System

Embedded system usually found as compact, portable and mass produced electronic devices. These condition require small, reliable and non-expensive processor. For this specification, we use microcontroller as processor. Microcontroller is relatively small, has on-chip  memory, I/O controller and other supported  modules to do processing and controlling tasks. Compactness and relatively low priced nature of a microcontroller, make is suitable for mass production.

Popular microcontroller architecture:

• 8051 family
• PIC
• AVR
• Motorola
• Zilog
• ARM
• MIPS
• etc..

For larger systems, we can use a PC as controller. Yes, PC is more expensive than microcontroller. It is also bigger. But sometimes we need the power of a PC to make our system  works. PC is faster, has larger storage, easier to program and do not need circuit design and manufacturing process. PC also has ready to use user interface such as monitor and keyboard. Those are some reasons why someone  put PC as controller of  ATM machine or Photo-booth, for example.

Now, imagine to use a PC (personal computer) as controller of our digital clock!

If someone talk about  embedded system, he usually talk about Microcontroller Based system not Computer Based system.

Embedded system which use computer as controller is usually called Embedded Computer (some guys also call it Embedded-PC). There are many kind of  computers can be use as in embedded computer system:

• Regular PC
• Industrial PC
• SBC (Single Board Computer)
• Modern PDA / Pocket PC / Handheld PC

Embedded systems is everywhere

If we understand the definition of embedded system, it is clear to see that embedded system has very large scope of applications. In fact, almost all modern electronic devices use some sort of embedded system technology inside them. To be clear, I give some examples:  DVD players, air conditioners, printers, time attendance machines, handphone, digital camera, GPS, ATM machines, photo-booths, avionic control system, …and thousands more..

Note:  PC, Modern PDA, Pocket PC, Handheld PC are NOT embedded systems in nature, because they are designed to be a multipurpose tools.

Other examples of electronic devices which are not embedded system:  simple radio receivers, simple electric fans, lamps, simple head phones, etc..