3.9 Booting the System for the First Time
3.9.2 Entering the BIOS configuration
When setting up the computer for the first time, it is necessary to run the CMOS Configuration Setup utility. As mentioned in the previous section, the computer checks the CMOS to determine what types of options are installed in the system. The system BIOS allows access to this configuration information through its CMOS Setup utility (recall that the CMOS refers to the type of integrated circuit that is used to store the BIOS configuration). Simply pressing the delete key during the opening boot sequence provides access to the BIOS on some computers. In general, early in the startup process the BIOS places a prompt on the display to tell the user that the CMOS Setup utility can be accessed by pressing a special key or a given key combination. Typical keys and key combinations include the ESC key, the DEL key, the F2 function key, and the CTRL-ALT-ESC key combination. Note that the keys or key combinations used to access the setup menus may vary from one BIOS manufacturer to another and sometimes from one BIOS version to another.

Press the proper key or key combinations within a predetermined amount of time in order to access the setup utility. If the keys are not pressed within that time, the BIOS program will continue with the boot-up process. The key commands stop the boot-up routine and display the main menu screen of the setup utility. The main menu on any given computer may be different from the one shown in the figure to the left, depending on which BIOS and version is being used. The values input through the BIOS setup are stored in the system CMOS configuration registers. These registers are examined each time the system is booted up in the future to tell the computer what types of devices are installed.