How CD-R and CD-RW work
CD-ROM drives (CD-R and CD-RW drives as well) read
the one and zero bits by difference in reflectivity. Mass
produced Compact Discs are created by stamping “pits”
in the CD. These “pits” reflect differently than the “land”
which is the area between “pits.”
CD-R drives work by using a laser beam to heat the
recording layer, causing a chemical reaction in that
spot so CD-ROM players will see this as a “pit” and
the unburnt area as “land.”
CD-RW uses what is known as a “Phase Change”
technology. In the CD-RW media is a substance which
can be changed from an amorphous “mark,” that very
closely resembles the pits of a stamped CD, to a crystalline
state which resembles “land.” The laser beam of the Sony
CD-RW Recorder Drive changes the crystalline state to the
amorphous state by use of a laser to quickly heat the spot
on the disc, forming a mark. To change the amorphous
state back to the crystalline state, the laser beam uses a
lower power setting to transition the mark back to the
crystalline “land.”
Performance
The CD-RW Recorder drive is capable of writing
CD-R discs at 8X speed and CD-RW discs at 4X (quad)
speed. Quad speed or 4X means that the drive can write
(also called record or burn) a CD-RW disc at 600 kilobytes
per second. This rate allows the drive to record a full 650
megabyte CD-RW disc in about 18 minutes. At 8X speed the
drive can write at 1200 kilobytes per second, or record a full
650 megabyte CD-R disc in only 9 minutes.
CD-RW Recorder User’s Guide
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CD-R and CD-RW
CD-R is the term used to denote CD-Recordable media.
CD-R discs are recorded permanently. Once information
is written, it cannot be erased. Data can be added until
the disc is full. CD-R is good for creating archived
information that need not be changed, or for distribution,
because the price of CD-R media has dropped rapidly in
the last few years.
CD-RW is the term used to denote CD-ReWritable media.
CD-RW discs can be written to many times. CD-RW media
is rated for one thousand different writes to the media.
CD-RW is perfect for personal file storage or for creating
reliable backups that can be added to as necessary, and
even rewritten as your backup scheme requires.
While CD-RW media is more expensive than CD-R media
it has a lower cost per megabyte than other competing
technologies, such as Magneto–Optical or even magnetic
removable media drives.
CD-RW drives are very versatile for transporting
information to both older and newer CD-ROM and
DVD-ROM drives. CD-RW media can be read by newer
CD-ROM and DVD-ROM drives. These newer drives are
known as Multi-Read (MR) drives. And even though
CD-RW media cannot be read by older CD-ROM drives,
the Sony CD-RW Recorder can write to CD-R media
which can be read by standard CD-ROM drives and
Audio CD Players.
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CD-RW Recorder User’s Guide
