>1. what is embedded system? what is the difference
>between a normal electronic system with a uC, with an
> embedded system?

The distinction that I make is embedded <-> open

- uC is embedded when the device performs a specific function, that could -
maybe in theory - also be performed by hard-wired digital or even analog
electronics, or by some mechanical, hydrolical etc. equivalent. In most
cases the user interaface is limited or even absent. The interaction with
the hardware is often important and takes a lot of the programming effort.
The hardware is often carefully cost-tuned for the specific purpose. Typical
examples: microwave oven, TV, car electronics, avoinics, watch, mouse.

- a uC is open (general purpose) when it is possible and often done to run a
customer-determined program on the uC. The user interface is often
important, and (consequently) the interaction with the user is often a large
part of the programming effort. The hardware is often design as a compromise
between widely varying ways of use. Typical examples: PC, mainframe, laptop.

There are of course examples that blurr the distinction:
- a Lego mindstorm brik that runs LegOS
- a mobile telephone that runs a game that has been downloaded from the
internet
- a playstation that runs Linux
- a PC without monitor and with a keyboard-simulator working as IP router

Wouter van Ooijen
van Ooijen Technische Informatica: http://www.xs4all.nl/~wf/index.html

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