Intel, Intel® 64 and IA-32 Architectures Software Developer Manuals, here.
These manuals describe the architecture and programming environment of the Intel® 64 and IA-32 architectures.
Electronic versions of these documents allow you to quickly get to the information you need and print only the pages you want. The Intel® 64 and IA-32 Architectures Software Developer’s Manuals are now available for download via a three volume set or a seven volume set. All content is identical in each set; see details below.
At present, downloadable PDFs of all volumes are at version 048. The downloadable PDF of the Intel® 64 and IA-32 Architectures Optimization Reference Manual is at version 028. Additional related specifications, application notes and white papers are also available for download.