I found this article to be exceptionally useful when using OpenBSD as a
primary development platform:
http://www.phiral.net/openbsdasm.htm
Hope that helps, the first few paragraphs of it anyway... :)
P.S: Both Intel and AMD have documentation available, they might be a
better start:
http://developer.amd.com/documentation/guides/Pages/default.aspx#manuals
http://www.intel.com/products/processor/manuals/
If you follow the "Order a printed copy" link on the Intel page, you can
get them free.. no shipping fees.
-Brynet.
