Daniel Seagraves wrote, in his classic style of leaving the body of the message devoid of any any actual context as to what he's asking about and requiring a reference to the Subject line: A *very* popular book for introducing this subject to students these days is _Computer Arithmetic: Algorithms and Hardware Designs_, by Behrooz Parhami. It's a pedantic, general purpose introduction, with an emphasis on conveying a true understanding of the subject through how the bits are actually banged about. An even more pedantic introduction is Donald Knuth's _The Art of Computer Programming, Vol 1: Fundamental Algorithms_. It's probably not so good as a introduction if you're really unfamiliar with the subject already, but it's a true classic in the field, and anyone who has worked in the field goes back to it every so often for some deep insight. For example, I just browsed through it a couple days ago for some grokking of how negative number base arithmetic works. Neat feature: no sign bit necessary! Another good reference, if you've already got some experience with computer architecture books and want to leverage this knowledge, is the IEEE Tutorial titled simply _Computer Arithmetic_ and edited by Earl E. Swartzlander. There's also Kai Hwang's _Computer Arithmetic: Principles, Architecture, and Design_ and Israel Koren's _Computer Arithmetic Algorithms_. I suspect that you just want a cheat-sheet for a few specific applications, in which case there's probably a Schaum's outline paperback that will get you by but without conveying any real understanding about how it works or why it works the way it does. I'm sure your local library has some similar workbook-style textbooks. Perhaps intermediate between the dumbed-down level of Schaum's Outlines and the high-and-lofty ivory tower view of Knuth would be a good numerical analysis text intended for scientists who have to learn the basics of how computers do arithmetic, and how this differs from traditional school-book arithmetic. _Numerical Recipes_ doesn't quite fit the bill, but when I was an undergrad I took several numerical analysis courses and all the textbooks had good, but terse, introductions to computer arithmetic, both fixed and floating-point. Again, I'm sure your local library has some good books. -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology WWW: http://www.trailing-edge.com/ 7328 Bradley Blvd Voice: 301-767-5917 Bethesda, MD, USA 20817 Fax: 301-767-5927