One of my University lecturers help at the London Science Museum to build the Babbage difference engine around twenty years ago.  Engines like this which is very mechanical based are obviously simple ways to implement functions of modern cpus in nano technology.  It was a a nice surprise to see the article "Antique engines inspire nano chip" where we see that this is progressing.

“The blueprint for a tiny, ultra-robust mechanical computer has been outlined by US researchers. ”What we are proposing is a new type of computing architecture that is only based on nano-mechanical elements,” said Professor Robert Blick of the University of Wisconsin-Madison and one of the authors of the journal paper. “We are not going to compete with high-speed silicon, but where we are competitive is for all of those mundane applications where you need microprocessors which can be slow and cheap as well.”

ttfn

David