EI & Embedded Scope

[mreccentric]

Hello Everybody,
I am learning about the concepts of railway signaling, and haven't been perfect though. I came to know that the latest technology/designs used are using embedded systems in practice. I agree that every other electronic system nowadays rely on embedded systems, but can i know what are the basics that need to be known?
I read one of the Green Books which dealt with Electronic Interlocking, but there was little information on embedded systems and it's related information.

Let me also know that how these electronic/embedded circuits are designed, and the scope.