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The minimum you need to know about CD-R and CD-RW

February 16, 1999
Web posted at: 4:29 p.m. EST (2129 GMT)

by Carla Catalano

Does your computer have a CD-R or CD-RW drive?

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(IDG) -- You may remember when CD-ROM really meant "read only." Today's writable compact disc technology allows end users to read and write reports, photos and presentations.

There are two types of writable CDs: CD-Recordable (CD-R) and CD-Rewritable (CD-RW).

Both allow CD-ROM-compatible discs to be created on the desktop.

These CDs are individually produced with an optical drive connected to the computer and require pregrooved CDs. Once recorded, the discs are like other CDs.

CD-R uses media that can be written to once at any location on the disc. You can add information to the disc, but you have to put it in a different place.

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"Think of CD-R as writing with a ballpoint pen. You can't erase or write over where you've already written," says Bob Katzive, vice president of Disk/Trend Inc. in Mountain View, Calif.

Archives, music and more

Mainly used for archival and distribution purposes, CD-R is for "folks who need to distribute information or back up from their hard drive," Katzive says. And because of its write-once, nonerasable format, CD-R safeguards against deleting or overwriting files.

A popular use for CD-R is making custom music CDs. Users also use CD-R to download files, such as screen savers and search results, from the Internet to prevent hard drives from corruption.

In contrast, CD-RW allows you to rewrite to the disc up to 1,000 times. Stored data on this type of disc isn't permanent because it can be erased and written over. CD-RW is like "writing with paper and pencil," Katzive says.

CD-RW allows you to reuse the media, so instead of having a large number of discs on hand, you can use the same disc again and again. CD-RW also is the "media of choice" -- it costs less than CD-R over time because you buy fewer discs. But more CD-R is sold because each disc is less expensive, according to Katzive.

There are some drawbacks to CD-R and CD-RW technology. Both are used to record audio, video and data, but "formatting is long and cumbersome," says Wolfgang Schlichting, an analyst at International Data Corp. in Framingham, Mass. The media is blank when you buy it, and it can take up to an hour to format a disc.

A major difference between the media is compatibility.

CD-R is read-compatible with CD-ROM drives, which adds to its popularity; however, CD-RW can be read only in multiread CD-ROM drives.

For example, if you record an audio CD and want to play it back on your CD player, you would use CD-R because the audio player can't read CD-RW.

If you want to play it back on your PC and the PC CD-ROM drive is multiread, then you would use CD-RW media.

Carla Catalano is a freelance writer in Holliston, Mass.

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