Intel. Intel Architecture Software Developer's Manual, vol. 3: System Programming Guide. 2005. Describes the Intel Pentium microprocessor architecture. It can be downloaded from: http://developer.intel.com/design/processors/pentium4/manuals/25366816.pdf.
Intel. MultiProcessor Specification, Version 1.4. 1997. Describes the Intel multiprocessor architecture specifications. It can be downloaded from http://www.intel.com/design/pentium/datashts/24201606.pdf.
Messmer, H. P. The Indispensable PC Hardware Book (4th ed.). Addison Wesley Professional, 2001. A valuable reference that exhaustively describes the many components of a PC.