You may need to boot from a CD if installing a new operating system such as Linux or Windows, or to fix problems with your operating system. While your computer system is likely set up to automatically boot from the hard drive of your computer, you can reconfigure it to boot from a CD by changing the boot sequence setting in the BIOS menu.
Enter the Computer's BIOS Menu
A computer's BIOS is the "Basic Input/Output System" software that starts the PC before the operating system takes over. You need to access the BIOS to boot from your CD drive. As your computer boots, the logo screen that displays should list options for entering the BIOS. If your computer has a "Setup" option with an F key beside it, pressing this key should take you into the BIOS menu. Some computers will not have this feature, however, and the keyboard command that takes you into the BIOS menu differs from model to model. If you have the manual for your computer, look up the key or key sequence. For Compaq PCs, press "F10" while the cursor blinks in the upper-right corner. On Dell computers, the command to enter the BIOS will be either "Ctrl+Alt+Enter," "F1" and "Delete," or simply "Reset" twice. For Sony computers, press "F3" as the computer boots and then either "F1" or "F2." A list of other key codes can be found at Cyberwalker.com.
Edit the Computer's BIOS Menu
When you enter the BIOS menu, a gray and blue BIOS screen will display. The top entry in the menu will be blue. Scroll down to highlight "Boot Sequence" and press the "Enter" key. The "Boot Device Priority" menu will appear. Select "First Boot Device" and press "Enter." Scroll down to the option that contains the words "CD-ROM Device" and press "Enter" to choose this device as your default boot device. The system will now boot from the CD drive first. If you haven't placed a CD in the drive, the computer will instead boot from the hard drive.