Bigelow explains, in great detail, how each subsystem of an IBM-compatible PC works. In the BIOS section, for example, he details the actions, in sequence, taken by various popular BIOS routines at boot up. The CD-ROM section describes exactly how to make a bootable CD-ROM that takes advantage of the El Torito standard. In other chapters, he takes on video monitors, processors from all three major vendors, DVD drives, diagnostic beep and power-on self test (POST) codes, modems, and tons more. Throughout, he combines excellent how it works text with bountiful reference material. Bigelow also has paid considerable attention to troubleshooting, concluding each chapter with statements of common problems and their solutions.A Symptoms at a Glance section lists common problems, along with references to the pages that describe what to do about them. This is a useful feature, but it would be easier to find a particular problem if the list were broken up by subsystem.