This Web site is a great reference for any assembly language programmers of the 32- or 64-bit x86 architectures. It has complete information about register locations and contents, instruction operation codes, and data representations. Details about interrupt and exception handling, as well as reset states, are also given. Aside from the architecture descriptions, profiles about specific implementations are offered. All major processor manufacturers are represented here, with facts about physical and electrical characteristics, clock frequencies, and more. The documents section is not accessible to the public.