2.2 The Boot Process
2.2.3 The boot sequence
The PC boot sequence defines the set of actions as well as the sequence of the actions that take place when the computer is started from a power-off status or when the PC is restarted with the power already on. The number of events that happen in the boot process depends on whether the user is doing a cold boot or a warm boot. The following is a description of each type of boot:
  • A cold boot begins whenever the PC power switch is turned on. The cold boot involves many more events and bootstrap (BIOS) activities than the warm boot. The cold boot causes the BIOS to guide the computer boot sequence through a series of steps that verify the integrity of the system.
  • A warm boot is performed whenever the PC is restarted or reset with the power still on. The warm boot is usually started using the Ctrl + Alt + Delete key sequence. It is a subset of the cold boot.

The exact steps in the boot process may vary depending on a number of factors that affect the computer. These include the BIOS manufacturer, BIOS version, and the system hardware configuration. The steps listed in Figure represent what generally happens when a user performs a cold boot on a PC. The order of the boot can be changed in setup.