CD-ROM, CD-RW, and DVD Drives

CD-ROM, CD-RW, and DVD Drives

Optical drives fall into two major categories:

• Those based on CD technology, including CD - ROM , CD -R (recordable CD ) , and CD -RW (rewritable CD )

• Those based on DVD technology, including DVD- ROM , DVD- RAM , DVD-R/RW , DVD+R/RW and DVD ±R/RW

tip

You should understand both read-only and recordable/rewritable CD and DVD standards to be prepared for the A+ Certification Exam and for your day-to-day work because these drives are found in virtually all recent computers.

How CD-ROM and DVD Drives Store Data

The data are stored in a continuous spiral of indentations called pits and lands on the nonlabel side of the media from the middle of the media outward to the edge. All drives use a laser to read data; DVD stores more data because it uses a laser on a shorter wavelength than CD-ROM and CD-RW drives do, allowing for smaller pits and lands and more data in the same space. CD-R and CD-RW drives use special media types and a more powerful laser to write data to the media. CD-R media is a write-once media ”the media can be written to during multiple sessions, but older data cannot be deleted. CD-RW media can be rewritten up to 1,000 times.

Similarly, DVD-R and DVD+R media is recordable, but not erasable, whereas DVD-RW and DVD+RW media uses a phase-change medium similar to CD-RW and can be rewritten up to 1,000 times. DVD-RAM can be rewritten up to 100,000 times, but DVD-RAM drives and media are less compatible with other types of DVD drives and media than the other rewritable DVD types, making DVD-RAM the least popular DVD format.

DVD Formats

A number of manufacturers now make various types of writeable DVD drives. There are actually five types of writeable DVD media, and because most drives can use only one or two types, it's essential that you buy the correct type.

• DVD-RAM ” A rewriteable/erasable media similar to CD-RW but more durable; it can be single or double sided. DVD-RAM is usually kept in a closed disc caddy to protect its surfaces.

• DVD-R ” A writeable/nonerasable media similar to CD-R; some DVD-RAM and all DVD-RW drives can use DVD-R media.

• DVD-RW ” A single-sided rewriteable/erasable media similar to CD-RW. DVD-RW drives can also write to DVD-R media.

• DVD+RW ” A rewriteable/erasable media. Also similar to CD-RW, but not interchangeable with DVD-RW or DVD-RAM.

• DVD+R ” A writeable/nonerasable media. Also similar to CD-R, but not interchangeable with DVD-R.

caution

Before using 4x or faster media in older DVD-R/RW drives, make sure you install the firmware update provided by the drive vendor. Otherwise, you will damage your drive if you attempt to use the faster media in the slower drive.

DVD-R/RW and DVD+R/RW media is now speed rated because the latest drives can write and rewrite data at faster rates than older drives.

Most DVD+RW and DVD-RW drives, along with some DVD-RAM drives, can also use CD-RW and CD-R media.

All rewritable media (CD-RW, DVD-RAM, DVD-RW, and DVD+RW) must be formatted before it can be used for drag-and-drop file copying. DVD+RW, second-generation and newer DVD-RW, and DVD-RAM drives support quick formatting, which takes less than a minute. Early DVD-RW and all CD-RW drives require up to an hour to format the media.

Although CD-mastering programs can also use rewriteable media, you should not use such media with these programs, as the media might not be erasable after being mastered. Use CD-R, DVD-R, or DVD+R media for CD- or DVD-mastering tasks .

Multiformat Drives

Many rewritable DVD drives now on the market are referred to as DVD ±R/RW, meaning that they can use either DVD-R/RW or DVD+R/RW media. Because DVD-ROM drives and DVD-Video players vary in their compatibility with recordable and rewritable DVD formats, multiformat drives like these ensure compatibility with a wide range of DVD devices.

Some recent DVD-RAM drives have also added write/rewrite compatibility with CD-R/RW and DVD-R/RW media to improve their compatibility with the more popular recordable and rewritable CD and DVD formats.

CD and DVD Capacities

The standard capacity of older CD-ROM drives is 650MB “74 minutes of music. Newer drives and CD-R/CD-RW media support 700MB “80 minutes of music; almost all media on the market today is the 700MB/80 minute media. Standard DVD drives support the DVD-5 standard, which stores 4.7GB on a single-sided, single-layer disk that is the same size as a CD-ROM but holds much more data and must be read by a different type of laser. DVD-RAM media can be single sided (4.7GB) or double sided (9.4GB).

These drives are most commonly connected through the ATA/IDE interface, where they are referred to as ATAPI devices , but some older models also connect through SCSI interfaces. Portable drives can use parallel, USB 1.1, USB 2.0 (Hi-Speed USB), IEEE-1394a, or PC Card interfaces ”USB 2.0 or IEEE-1394a are the most common interfaces on recent models. Optical drives are installed the same way as other drives using the same interfaces.

CD and DVD Speed Ratings

Drive speeds are measured by an X-rating :

• On CD-based drives, 1X equals 150KBps, the data transfer rate used for reading music CDs. Multiply the X-rating by 150 to determine the drive's data rate for reading, writing, or rewriting CD media.

• On DVD-based drives, 1X equals 1.385MBps when working with DVD media; this is the data transfer rate used for playing DVD-Video (DVD movies) content. Multiply the X-rating by 1.385 to determine the drive's data rate for reading, writing, or rewriting DVD media. When DVD drives read, write, or rewrite CD media, they do so at speeds comparable to CD drives.

Most drives run at variable speeds to hold down costs; therefore, a so-called 52X drive produces its maximum 7,500KBps transfer rate only when it is reading the outer edges of the media on a full CD. For drives that work with different types of media, each media type is listed for the drive. For example, a drive that reads CD-ROMs at 50X (maximum), writes CD-R media at 40X, and rewrites CD-RW media at 24X would be said to have a speed rating of 40X/24X/50X; the usual speed order is CD-R/CD-RW/CD-ROM. A DVD drive that can read DVD media at 10X and CD-ROMs at 40X would be referred to as a 10X DVD (40X CD-ROM) drive.

Rewritable DVD drives usually list their speeds in this order:

• DVD write

• DVD rewrite

• DVD read

• CD write

• CD rewrite

• CD read

Installing Optical Drives

The installation of these drives follows the standard procedure used for each interface type. For example, ATAPI/IDE CD-ROM drives are set as master, slave, or cable select (depending upon the cable type); SCSI CD-ROM drives must be set to a unique device ID; and so on. If you want to play music CDs through your sound card's speakers , especially with older versions of Windows, make sure you run the CD audio patch cable supplied with the drive to the CD audio jack on the sound card. Older drives support a four-wire analog cable, whereas newer drives support both the four-wire analog and newer two-wire digital cable. The digital cable provides for faster speed when ripping music CDs ( ripping is the process of converting music CD tracks into compressed digital music files such as MP3 and WMA). Figure 14.22 shows a typical optical drive before and after connecting power, data, and music cables.

Figure 14.22. A typical optical drive before (top) and after (bottom) data, power, and CD music cables have been attached.

You might still be able to play CDs on your system provided you don't use an analog or digital patch cable if the installed media player software converts the CD audio into digital audio first. However, this can delay playback and the results might not be as good if you use the analog or digital cable connection to the optical drive.

Enabling CD and DVD Recording Features

All optical drives except for DVD-RAM drives are treated as CD-ROM or DVD-ROM drives by all versions of Windows; DVD-RAM drives are recognized as rewritable drives by all versions of Windows.

Windows XP provides rudimentary CD-R/RW recording capabilities with both CD-R/RW and rewritable DVD drives. However, commercial software such as Nero, Roxio Easy CD and DVD Creator, and others is highly recommended with Windows XP and is required with other versions of Windows in order to use the rewritable/recordable features of CD and DVD drives. Most rewritable drives sold at stores are equipped with some version of one or more of these programs. However, some computer vendors rely on the Windows XP recording feature to support their bundled CD-RW drives.

Windows XP's CD-writing capability is automatically activated for any CD or DVD rewritable drive (although only CD-R/RW media is supported). To write files to the drive, insert a blank disc, drag files to the CD/DVD drive icon using Windows Explorer/My Computer, and click the CD/DVD drive icon. When the drive icon opens, files waiting to be written are listed. Click the task menu option Write These Files to CD. The files are written, albeit much more slowly than if you use a commercial CD-mastering or packet-writing program.

Because Windows XP doesn't format a CD-RW disc the same way a packet-writing program such as DirectCD, InCD, or DLA does, you cannot use a third-party program to erase files from a CD-RW disc written by Windows XP. You must use Windows XP to erase unwanted files. You can then reformat the media as desired with a different program.

To erase files from a CD-RW disc, place the disc in the drive, open its icon in Windows Explorer/My Computer, select the file(s) to erase, and erase them.

IDE/ATAPI Installation Issues

Generally, because data frequently is copied from a CD-ROM drive to the hard drive or from a hard drive to a CD-RW drive, ATAPI CD-ROM drives should be connected to the secondary IDE interface, and hard drives should be connected to the primary IDE interface.

On newer systems with CD-ROM as an available drive type in the system BIOS setup, be sure to set the BIOS drive type as CD-ROM for any optical drive. If you want to use the optical drive as a bootable device for use with Windows 2000/XP or vendor-supplied system recovery CDs, be sure that the optical drive (CD-ROM) is specified as the first device in the boot order.