The following is not meant to be a comprehensive Unix bibliography. For that, see the Unix book list posted periodically to misc.books.technical and to several comp.unix newsgroups. Comments not in quotes below are mine.
Comments sent in by others are in quotes, and have the name of the commentor in square brackets.
This is a book I bought when I was struggling with an AT-clone. Still, there is a wealth of information common to all models. EISA and VESA are mentioned only in the glossary. Pin connections, timing, waveforms, block diagrams, voltages, all that kind of stuff. Part I. Applications Programming, data types, memory model, instruction set.