Digital circuit notation conventions

I figure this is at least somewhat on topic. I've been reading through _The Art of Digital Design_ by Prosser and Winkel [1] to with the intention of building the PDP-8/I clone project outlined in the book. I skipped ahead to the meaty chapters outlining the design of the system; I found myself pleasantly surprised. I can say that I've a reasonable understanding of how it all works. I can certainly understand the fascination people have with the "8"; it's not that hard at all to wrap one's brain around it. Having satisified myself that I'm up to the task, I've now moved to reading the initial chapters so I'll understand the basics. There are a few rough spots where I feel the authors impatiently gloss over some of the topics. And then there's one section in the second chapter where they basically deride "postive logic" and "negative logic" notation conventions as evil while promoting what they claim to be their own "mixed logic" convention. Methought they protested /a bit/ too much, and not being familiar with what it proper or put into practive, I pulled out Horowitz and Hill [2] to see what they had to say. From what I can tell, they seem to be advocates of "assertion-level logic" notation--which looks to be the same as Prosser and Winkel's mixed logic. What I'm wondering is whether mixed logic and assertion-level logic notations are in fact the same, and then which notation convention(s) are most commonly found in practice. It was only a decade ago that I had my intro to digital logic design lectures and labs, but I don't remember there being any discussion of different notation conventions. Then again, it's possible that ten years worth of software knowledge has squeezed out what hardware bits we covered. -brian. [1] The Art of Digital Electronics: An Introduction to Top-Down Design, 2nd Ed, Franklin P. Prosser and David E. Winkel, Prentice Hall, 1987. [2] The Art of Electronics, 2nd Ed., Paul Horowitz and Winfield Hill, Cambridge University Press, 1989.