Every computer user should know the basic computer troubleshooting and setup techniques. One of the most important tasks that you need to know about is the installation of a computer operating system. This requires that you know how booting from optical disks is done.
How it Works
Booting from a disk is actually loading an operating system, whose contents are burned on it. One of the most common reasons for booting this way is the installation of a new OS, while another reason might be to repair an existing installation.
When a computer is started, it first goes through the POST (Power-on Self Test) schedule to ensure that all the basic systems are working; after which its control is passed over to BIOS (Basic Input Output System), which handles the OS booting. The BIOS is a set of basic software programs stored in a memory chip on the computer motherboard and it controls all the hardware-level functions of all input and output systems. If you need to make any hardware-level changes, you need to edit BIOS settings.
The process is handled by BIOS, via the boot loader program that is pre-installed in it. This program has a specific boot order of storage media, from which it loads an OS. If the order has the hard drive listed at the top, your computer won't be able to do it from an optical disc, but it will directly load the OS from the hard drive. Most computers are configured by default to have the DVD-ROM as the first device in boot order, to facilitate booting from it. However, if it is not so, you will have to change the order settings.
Setting up BIOS
To set the BIOS order to boot from any disk, switch on your computer. As soon as the POST message disappears and its diagnostic tests are over, you will see a message which will mostly say 'Press Del to Enter BIOS Setup'. It will either be the Delete key or F2 key which may have to be pressed to enter the BIOS setup. Once the setup screen shows itself, locate the boot order settings, and follow the instructions provided to set the DVD or CD drive to be the top choice. Once you have changed the order, save the settings and exit.
To be able to boot from any optical disc, your computer needs to be equipped with a DVD-ROM, to be able to load the operating system.
To boot from any CD or DVD on a Windows machine, you will obviously need the Windows XP, Vista or Windows 7 installation or recovery disc. Just insert the DVD or CD in the drive and restart the computer. Again, if the boot order is set right, your computer's BIOS will automatically load Windows and its set up screen will appear. For installation or repair, you must then follow on-screen instructions.