Why do you need booting your computer from CD or DVD?
Booting from a CD is sometimes necessary to run advanced tools like memory testing programs and password recovery tools. You'll also need to boot to a CD or DVD if you're planning to install an operating system like Windows XP or run diagnostic tools like the Windows XP Recovery Console. When you boot from a CD, what you're actually doing is running your computer with a small operating system that's installed on the CD. When you start your computer normally, you're running with the operating system installed on your hard drive - Windows, Linux, etc.
When do you need booting your computer from CD or DVD?
- Your Hard Drive is corrupted and you cannot boot up through the conventional options. You usually try first more simple options of recovery like Safe Mode or Last Working Bootup Configuration. The sample of error message you might get is as follows: "Boot sector corrupt. Config.sys missing. Disk cannot be read."
- You forgot your administrative password, and you cannot login to your locked computer a regular way.
- Your computer is infected with virus, and you need to perform a deep Hard Drive cleaning, including the basic drivers, through external operational features.
- You need to manipulate the Operating System drivers that constitute the core of the system, and are used by it even in the light Safe Mode. For example, you need to perform manual rebase of the basic Windows drivers to increase virtual memory interval for the high memory resources consuming software utility.
- You need to perform Hard Drive imaging for backup purposes. Many utilities require booting up from the DOS or Linux external environment.
Time Required: Booting from a CD or DVD usually takes less than 10 to 20 minutes.
- Change the BIOS boot order so the CD or DVD drive is listed first. Some computers are already configured this way but many are not. Usually, the key required to press, to enter BIOS, is shown on the first page. However, you need to click fast (sometimes, repeating multiple times) to ensure that your request has been processed. The key or keys combination depends on the computer model and manufacturer.
If the CD or DVD drive is not first in the boot order, your PC will start "normally" (i.e. boot from your hard drive) without even looking at what might be in your disc drive.
Note: After setting your optical drive as the first boot device in BIOS, your computer will check that drive for a bootable CD or DVD each time your computer starts. Leaving your PC configured this way shouldn't cause problems unless you plan on leaving a disc in the drive all the time.
- Insert your bootable CD or bootable DVD in your disc drive.
How do you know if a CD or DVD is bootable? The easiest way to find out if a disc is bootable is to insert it in your drive and follow the remainder of these instructions. Most operating system setup CDs and DVDs are bootable, as are many advanced diagnostic tools.
Note: Programs downloadable from the Internet that are intended to be bootable discs are usually made available in ISO format.
3. Restart your computer.
4. Watch for a Press any key to boot from CD... message.
When booting to a Windows setup CD/DVD and many other bootable discs, you may be prompted with a message to press a key to boot to the disc. To boot to the CD or DVD, you'll need to press any key on your keyboard (like the space bar) within the few seconds that the message is on the screen.
If you do nothing, your computer will check for boot information on the next boot device in the list in BIOS which will probably be your hard drive.
Some bootable CDs and DVDs do not prompt for a key press and will start immediately.
5. Your computer should now boot from the CD or DVD disc.
Note: What happens now depends on what the bootable disc was for. If you're booting to a Windows Vista DVD, the Windows Vista setup program will begin. If you're booting to a Slackware Live CD, the version of the Slackware Linux operating system you've included on the CD will run.
If you tried the above steps but your computer did not boot from the CD or DVD properly, check out some of the tips below.
- Recheck the boot order in BIOS. The number one reason a bootable disc won't boot is because BIOS is not configured to check the CD/DVD drive first.
- Do you have more than one CD or DVD drive? Your computer probably only allows for one of your disc drives to be booted from. Insert the bootable CD or DVD in the other drive and restart your computer.
- Clean the CD or DVD. If the disc is old, as are many Windows Setup CDs and DVDs by the time they're needed, clean it. A clean disc could make all the difference.
- Burn a new CD/DVD. If the DVD or CD is one you created yourself, like from an ISO file, then burn it again. The disc may have errors on it that re-burning could correct. I've had this happen to me more than once.
- Check CD-ROM jumpers. Not all CD-ROM drives will boot properly if the jumpers are not set properly; verify that the CD-ROM drive has the jumpers set properly. We generally recommend that you have the CD-ROM set as master on the secondary controller. This rule also applies to portable computers.
- Check if your CD-ROM is operational. Verify other CD discs work in the CD drive. If the drive is a bad drive it will be unable to boot from the CD disc because it cannot read from the disc.
Types of Bootable CDs and DVDs:
There are multiple bootable CDs and DVDs, starting from the Operation System CD you received with the computer purchase. Aftermarket offers multiple disks configurations, as legal, based on the free operating systems, as not very legal, like portable Windows compilations. We will review some of the options in the following articles of this chapter.