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CD Recorders, often referred to as CD
burners, are becoming standard equipment on personal computers. CD
recorders allow users to "burn" their own CDs containing
music, data, video, or any combination thereof. Users can now create
their own compilation audio CDs, make backup copies of software,
backup their critical data, and create VCDs (Video CDs) that can be
played in stand-alone DVD players. The inexpensive price of the drive
and media coupled with the generous capacity of a CD has made owning a
CD recorder very desirable.
Currently there are two major types of CD recorders:
- CD-R – CD-R stands for Compact Disc - Recordable
and was the first of the two technologies conceived. Commercially
produced CDs, be it audio or other databased information, are
"pressed" in great volume. This pressing technique
produces the lands and pit areas of the CD that the laser assembly
reads. CD-R technology uses a different strategy for writing
information to a CD. CD-R media adds a layer of dye between the
aluminum and plastic layers. This layer of dye is translucent and
allows light to shine through to the aluminum layer that reflects
the light back. When a CD-R drive writes information to the CD-R
media, a laser is used to burn areas of the dye to create opaque,
non-reflective spots. When the recorded CD-R is read, the laser
assembly receives reflections from only the translucent areas of
dye. This reflective/non-reflective surface easily translates into
bits of data. To accomplish the job of reading and writing CDs,
CD-R drives use two lasers. These include a read laser and a write
laser. The
speed at which a CD-R can burn a CD uses the same "number
times" convention as a traditional CD-ROM drive read speed. A
CD-R drive that can write at 3000kb per second is shown as having
a 20x (or 20 times 150kb) write speed. A drive listed as 24x/40x
has a write speed of 24x and a read speed of 40x. One downside of
CD-R media is that it cannot be re-written to.
- CD-RW – CD-RW stands for Compact Disc - Rewritable. Like
CD-R drives, CD-RW drives require the use of a special type of
disc. While unlike CD-R media, the CD-RW disc is mostly
incompatible with other CD reading drives. CD-RW media is unique
in that it includes a phase-change compound layer between the
aluminum and plastic layers. This compound is a special mix of
chemical elements that can change physical states at certain
temperatures and remain in that state indefinitely. The compound
begins in a translucent crystalline state that allows light to pass
through to the reflective aluminum layer. When the CD-RW write laser
is used to burn information to the disc, certain areas of the
phase-change compound are melted by super-heating and held in that
phase by rapid cooling. These melted areas are opaque and
non-reflective. What makes a CD-RW drive unique is that they include
a third eraser laser. The eraser laser is used to slowly reheat
melted areas of the phase-change compound into the crystalline
state. This is what allows the rewriting of CDs. Similar to CD-R
drives, CD-RW drives are rated by the speed at which they write,
rewrite, and read information. A CD-RW drive listed as 24x/12x/40x
has a write speed of 24x, a rewrite speed of 12x, and a read speed
of 40x.
Copyright Issues
As a PC technician, it is highly recommended to be on the lookout
for copyright or licensing limitations when copying any type of
CD. There are instances when it is necessary to make a copy of a
CD. One example is the need to keep backup copies of the original
installation CDs. Become familiar with the copyright or licensing
agreements associated with the purchase to avoid conflicts with
legal issues.
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