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Recordable CD (CD-R)

While CD-ROMs are an amazingly useful medium, and have revolutionized how the average person uses his or her PC, the sticking point with them has always been that they were a read-only medium. Not everyone has a CD press in their basement, and while it is possible to get commercially-produced CDs today in small volumes, this typically still means 1,000 disks and several thousands dollars.

In 1990, part II of the so-called "orange book" published by Philips (who else), specified the characteristics and format of a recordable CD, or CD-R. CD-R is also sometimes called CD-WORM or CD-WO, where WO means "write once" and WORM "write once read many", both reflecting truisms about the medium. (There are other types of drives that are also WORM however.)

CD-R drives, and the media they use, allow a regular PC user to create audio or data CDs in various formats that can be read by most normal CD players or CD-ROM drives, at a reasonable cost. As "write once" implies, the disks start out blank, can be recorded once, and thereafter are permanent and not re-recordable. Part III of the "orange book" defines rewriteable CDs, which are erasable, unlike CD-R.

Note: Part I of the "orange book" contains the specifications for magneto-optical (MO) drives.

CD-R is more than just another standard CD format. CD-ROM, CD-ROM XA, CD-I, etc. built upon the original CD audio standard by simply changing the interpretation of what the bytes in the original CD audio format meant. CD-R is actually in many ways the opposite: it defines new physical media and ways of recording them, while continuing to use the standard formats defined in other specifications.

Initially, CD-R was prohibitively expensive--well over $1,000 for a drive, and $10 or more for each blank disk. As both of these numbers have dropped in half or less, CD-R has become quite popular for several applications, including archiving, software distribution, backup, custom audio, and a host of others. This section takes a look at CD-R in a fair bit of detail, although certainly not exhaustively; there are enough descriptions and aspects related to CD-R to fill a chapter as big as everything I have written about CD-ROMs in general, easily.

See the CD-R FAQ for more information.

Next: CD-R Media and Encoding

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