CDs and DVDs | PC Users Bible

Compact discs (CDs) have replaced floppies as the universal medium for distributing programs and sharing data on personal computers. A CD drive (or a DVD drive that can also read and write CDs) is a standard part of every new personal computer. DVDs (Digital Video Discs or Digital Versatile Discs) are a newer type of optical storage media that are becoming common in new systems.

Both CDs and DVDs were originally designed as media for distributing commercially recorded entertainment. CDs began as media for music and other audio recordings, and DVDs for movies and other video programs. But they're both digital media, so it's just as easy to use them to carry computer programs and data files instead of rap singers or old sitcoms. As a side benefit, you can also use your computer's CD or DVD drive to play entertainment disks. The data formats are different for audio, video, and data, but the basic principles are similar.

The first CD drives for computers were CD-ROM drives-Compact Disc, Read-Only Memory-that could read CDs but couldn't create new ones. Today, almost all CD drives can also store data on recordable discs. Recordable discs come in two forms: CD-Rs (Compact Disc, Recordable) that can write data just once, and CD-RWs (Compact Disc, ReWritable) that can be erased and rewritten.

Data (or music or digital video) is stored on CDs and DVDs as pits in the surface of the disc, arranged in a spiral. The presence or absence of each pit corresponds to a digital data bit. The drive shines a very tightly focused light beam (a laser) at the disc and uses a photosensor to detect each pit. Because they use light to read the discs, both CDs and DVDs are known as optical media.

DVDs use a more advanced laser technology than CDs. The design and performance of the laser, the construction of the discs, and the format of the data are all more complex than the older CD technology. For most of us, the practical difference between CDs and DVDs is the amount of data that each disc can hold. Most data CDs have a capacity of about 700MB (or about 80 minutes of audio); DVDs can hold about 4.7GB today, but as the design evolves, the capacity of a single disc will continue to increase.

The original audio CDs were designed to spin at a speed that was adequate to convert the digital data on the discs to analog sound. There was no reason to increase the speed, because the music wouldn't sound any better if you moved it from the disc to a buffer more quickly. But when you're making your own recordings, and when you're reading and writing computer data, spinning the drive more quickly can reduce the time needed to complete the job. So CD drives for computers (and stand-alone audio CD recorders) use faster motors than audio CD players.

A faster CD drive can make a dramatic difference: at 1X (audio speed), it takes over an hour to fill a 700MB disc. At 8X (eight times faster), you can fill the same disc in nine minutes. And at 48X, the time to fill the disc is just 90 seconds. However, it's essential to use CD media designed for high-speed recording; look on the disc packaging to find the range of speeds that the discs can support, and use the options settings menu in your CD burning program to set a speed at or below the drive's maximum speed.

Tip

If you have a choice, don't try to record CDs at the highest possible speed your drive and media allows. Dropping the speed by about 10–20 percent often provides much more reliable performance, and reduces or eliminates the number of ruined CDs.

CD and DVD drives use the same data interfaces as hard disk drives: IDE, SATA, and SCSI. To install a new drive, follow these steps:

Turn off the computer.
Remove the cover from the case. If you have an anti-static wrist strap, put it on and ground yourself to the case.
Remove the faceplate from an unused external drive bay.
Set the jumper on the drive to either Master or Slave (if it's an IDE drive).
Mount the drive in the bay. Line up the face of the drive with the front of the computer case and use the screws supplied with the drive to secure the drive to the frame.
Connect the power and data cables to the new drive. If it's not already connected, plug the other end of the data cable into the motherboard. For best performance, connect the new drive to the Secondary IDE socket (the one that is not connected to the Primary hard drive).
Turn on the computer and immediately press the key that starts the BIOS Settings utility.
Move to the BIOS Settings Utility's screen that lists the IDE and SATA drives and find the listing for the new drive.
Choose the Auto-Detect option. The utility should identify the drive as a CD or DVD drive.
Use the Esc key or the F10 key to close the BIOS utility and save your new settings. Windows restarts.
Windows should automatically detect the new drive.
If a software CD was supplied with the drive, insert the disk in the drive and run the Setup program.