Predictability and Determinism

I was listening as usual to some of my audio books while driving from and to work and one sentence was blowing my mind. It was something like “Determinism is not the same with Predictability”.
This is quite mind boggling, since after working some years now with embedded and real-time systems my idea about those real-time systems is in the meantime, that the more real-time they are, the more predictable they are.

Now what does this mean?
One of my fundamental design rules is: The more interrupts there are, the more unpredictable the system becomes.
Mr. Laplante puts it even worse. If you just have one interrupt you cannot predict anymore what will happen.

There seem to be two different kinds of animals when we are talking about real-time stuff. What is real-time stuff anyhow? We are going to talk about this in some other blog.

… this is incomplete and more will follow…