Many thanks for that. Could you also comment on what the examiner says on page 30 with respect to independent clock signals and asynchronism?

My 2 cents. Using the reference book, examiner first states independent clock signals are part of asynchronous system. (and fails to mention anything else). Then goes on to say independent clock signals are simply different clock frequencies. (I wonder if the book actually says that?). Then concludes that different clock frequencies means Kato is asynchronous. At least I think that is what he is trying to say.

As I understand it, we are not able to provide any new material to aid in our defense. But I really wonder if the Computational Structures reference really provides anything to back up the examiner. I ran across another reference book called Low-Power CMOS Circuits by Christian Piguet and it says the following:

<Globally asynchronous and locally synchronous systems contain several independent synchronous blocks that operate with their own local clock and communicate asynchronously with each other. The main features of these systems is the abscense of a global timing reference and the use of several distinct clocks, or clock domains, possibly running at different frequencies. >

Seems they don't think different frequencies are necessary. I hope Computational Structures has some similar wording somewhere. Opty

http://books.google.com/books?id=xnz...