PC Hardware in a Nutshell, 3rd Edition

Firmware Components and the PC BIOS

Firmware is a special class of software, so called because it is more or less permanently stored on chips. Firmware is often referred to generically as a BIOS (Basic Input/Output System) because the only firmware contained in early PCs was the main system ROM-BIOS (Read-Only Memory BIOS). That’s no longer true. Nearly every component in a modern PC contains its own firmware. Disk drives, SCSI host adapters, video cards, sound cards, keyboards, and most other devices contain firmware, and nowadays that firmware is seldom read-only.

Tip

Although few people do so, installing firmware updates is an important part of keeping a modern PC functioning at its best. For example, firmware for most CD writers is frequently updated to add support for new types of blank media. The most important firmware to keep updated is the main system BIOS. Good motherboard makers frequently release updated BIOS versions that add functionality, fix bugs, support faster processor speeds, and so on.

The two most important pieces of firmware in a PC are the chipset—which technically is intermediate between hardware and firmware—and the main system BIOS. The chipset is the heart of the PC. Its capabilities determine such fundamental issues as which processors the motherboard supports, how data is communicated between processor and memory, and so on. The BIOS manages the basic configuration information stored in nonvolatile CMOS memory, such as the list of installed devices, ...