Looking for the free book? Worry not! It has moved home to the following location on GitHub:https://github.com/NormanDunbar/QLAssemblyLanguageBook/releases/tag/June_2015.
There you will find the pdf that you seek, and all the LaTeX source code that went in to making the book look how it does. You don't need this of course, unless you want to edit then text and fix any bugs in the book.