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Learning More About Your Computer 5–5
Understanding Computer Terms
CD-I
A compact disc format developed by Philips, designed to allow
interactive multimedia applications to be run on a player attached to a
television. The standard document defining CD-I is called the Green
Book.
CD-R (CD-recordable)
Media used in a CD-R drive to record or write data that cannot be
erased. The base is a circular piece of clear plastic, molded with a
spiral track to ensure that the CD-R drive follows the same spiral path
as that stamped on a conventional CD. The plastic layer is covered
first with an organic dye that is photosensitive, then a reflective layer
of silver alloy or 24-carat gold, and finally lacquer to protect the metal
from air and dust. Depending on the dye and metal used in
manufacture, the disc may be gold/gold (gold on top and bottom),
green/ gold, silver/blue, or silver/silver. When referring to CD media,
“CD-R” is often used to refer to write-once CDs in contrast to
CD-RW.
CD-R drive
Drive that uses a low-power laser to burn pits into the dye layer of a
CD-R, on which digital data is written. The marks are permanent.
When the finalized disc is played or read, the metal layer reflects laser
light in much the same way as the aluminum layer in a music CD or
CD-ROM. For this reason, the write-once CD-R can be read by most
of the newer CD players, CD-ROM, and DVD-ROM drives.
CD-ROM (CD Read-Only Media)
Media used in a CD-ROM drive. The data is read-only; you cannot
erase or record over it. The disc has three layers. The base is a circular
piece of clear plastic, mechanically stamped with tiny indentations, or
pits, in which digital data is written. The plastic layer is covered with
a sheet of shiny aluminum to reflect laser light; and the aluminum is
coated with lacquer to protect it from air and dust. Specifications for
the CD-ROM were first defined in the Yellow Book.