10.8. DVDs: An Introduction
Depending on who you ask, DVD stands for either "Digital Video Disc" or "Digital Versatile Disc." The dozen corporations on the DVD creation committee never agreed upon an official name . Whatever they're called, DVDs hold either 4.7 GB or 8.5 GB of information, making them especially suited for digital video and other whopper files.
CD drives and DVD drives look almost identical in a PC. But DVD drives are always stamped with the letters "DVD" on the front. For a sure-fire test, insert a DVD into the drive, and see if you can see any files on it. Open My Computer (Start My Computer), right-click your DVD drive, and from the shortcut menu, choose Explore. A DVD drive lets you see the discs files; a CD drive won't even be able to tell you've inserted a disc.
Unfortunately, DVDs somehow slipped in under Microsoft's radar. Windows XP doesn't contain any built-in tools for saving files to DVDs, or even for watching the movies stored on them. The following sections explain how to do both on your PC with a little help from some additional programs.
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Burning an ISO Image
An ISO image is a single file containing an exact copy of an entire CD: its files, folder structure, and even any hidden files the CD may need to function properly. Burning the ISO image file onto a blank CD recreates the original CD and is a handy way to store an entire CD's contents as a backup or for downloading from the Internet.
Most ISO images contain "bootable" CDsCDs that contain an operating system. For instance, when you stick a bootable CD into your CD drive and restart your PC, the PC loads the operating system from the CD, not the hard drive, neatly bypassing Windows XP. That comes in handy for several reasons.
Testing . Some hard drive testing programs (Section 9.7) need full control of the hard drive, something they'll never have when Windows XP's already running. To bypass Windows XP, troubleshooters download an ISO image of the testing program, burn it to a CD, and restart their PC from that CD. That lets them check the drive's mechanics without interference from Windows XP.
Updating BIOS and other firmware . If your PC's BIOSthe tiny software living inside its chips that hands control over to Windowsneeds a new version, most PCs boot off a floppy. But since notebooks (and many PCs) no longer have floppy drives, owners can download an ISO image, burn a CD, and boot their computer from that CD to update the firmware. Sometimes the CD or DVD drive in a home stereo needs a firmware update to fix a problem; the manufacturer places an ISO image on their Web site for customers to download, burn, and play in their afflicted player.
Distributing operating systems . The retail version of Windows XP comes on a "bootable" CD; so do other operating systems. The Knoppix CD (www.knoppix.org), a version of the Linux operating system, also comes as a downloadable ISO image. Start your PC with the Knoppix CD in the drive, and your PC wakes up running Linux instead of Windows XP, which is handy should you want to see what Linux looks like. (Or use it to salvage your data should Windows XP crash.)
Storing software . The hard drives of some new PCs contain ISO images of the PC's original installation CDs. If a PC owner wants to erase Windows XP and start over from scratch, she can burn CDs from those ISO images, recreate her PC's installation CDs, and use them to restore her PC to its "as purchased" condition.
Granted, very few people burn ISO images on a typical day. That's what Microsoft figured, so it didn't add ISO creation to Windows XP's small bag of CD burning tools. To burn an ISO image, you need third-party software like Nero (www.nero.com) or the free ISO Recorder (http://isorecorder.alexfeinman.com/isorecorder.htm).