What is the BIOS actually doing when I turn on my computer?
When you turn on your computer, several events occur automatically: • The CPU “wakes up” (has power) and reads the x86 code in the BIOS chip. • The code in the BIOS chip runs a series of tests, called the POST for Power On Self Test, to make sure the system devices are working correctly. In general, the BIOS: • Initializes system hardware and chipset registers • Initializes power management • Tests RAM (Random Access Memory) • Enables the keyboard • Tests serial and parallel ports • Initializes floppy disk drives and hard disk drive controllers • Displays system summary information • During POST, the BIOS compares the system configuration data obtained from POST with the system information stored on a CMOS – Complementary Metal-Oxide Semiconductor – memory chip located on the motherboard. (This CMOS chip, which is updated whenever new system components are added, contains the latest information about system components.) • After the POST tasks are completed, the BIOS looks for the boot
