I'm not sure if I like introducing computer science with a physical "computer". A physical "computer" is an application of computer science. I rather start with an abstract idea of computation, but my view point is very skewed towards academia. I'd love to hear what others have to say about this approach.
Hi Highwind. I start with the physical computer because that's what most people think of when you say "computer". If you read through to part five, I make exactly the point you do - the computer is the software (more accurately an implementation of a Universal Turing Machine) not the hardware at all.