Compact Disc Rewritable


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Compact Disc Rewritable

(storage)
(CD-RW) A rewritable version of CD-ROM. A CD-RW drive can write about 650 megabytes of data to CD-RW media an unlimited number of times. Most CD-RW drives can also write once to CD-R media.

CD-RW media cannot be read by CD-ROM drives built prior to 1997 due to the reduced reflectivity (15% compared to 70%) of CD-RW media.

CD-RW drives and media are currently (1999) more expensive than CD-R drives and media. CD-R is sometimes considered a better technology for archival purposes as the data cannot be accidentally modified or tampered with, and encourages better archival practices.

Standard prerecorded CDs have their information permanently stamped into an aluminium reflecting layer. CD-WR discs have a phase-change recording layer and an additional silver (aluminium) reflecting layer.

A laser beam can melt crystals in the recording layer into a non-crystalline amorphous phase or anneal them slowly at a lower temperature back to the crystalline state. The different reflectance of the areas make them appear as the 'pits' and 'lands' of a standard CD.

Phillips: New Technologies.

See also CD-R and DVD-RAM.
References in periodicals archive ?
The IBM ThinkPad R40 is powered by Intel(R) Centrino(TM) Mobile Technology and is outfitted with a compact disc rewritable (CDR) drive and wireless connectivity.
The logo will enable consumers to recognize CD and DVD players that can utilize Compact Disc Recordable (CD-R) and Compact Disc ReWritable (CD-RW) discs recorded on personal computers, and do so as readily as they use pressed discs.

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