Microsoft Office Tutorials and References
In Depth Information
COM 15
STORAGE DEVICES
OPTICAL DISC FORMATS
Optical Disc
A CD-R (compact disc-recordable) is an optical disc onto which you
can record your own items such as text, graphics, and audio. With a
CD-R, you can write on part of the disc at one time and another part at
a later time. Once you have recorded the CD-R, you can read from it as
many times as you wish. You can write on each part only one time, and
you cannot erase the disc’s contents. Most CD-ROM drives can read
a CD-R.
A CD-RW (compact disc-rewriteable) is an erasable optical disc you
can write on multiple times. A CD-RW overcomes the major
disadvantage of CD-R discs, which is that you can write on them only once. With
CD-RWs, the disc acts like a floppy or hard disk, allowing you to write
and rewrite data, instructions, and information onto it multiple times.
Although CDs have large storage capacities, even a CD cannot hold
many of today’s complex programs. Some software, for example, is sold
on five or more CDs. To meet these tremendous storage requirements,
some software companies have moved from CDs to the larger DVDs —
a technology that can be used to store large amounts of text and even
videos (Figure 20).
Read Write Erase
CD-ROM
Y
NN
CD-R
Y
Y
N
CD-RW
Y
Y
Y
DVD-ROM
Y
NN
BD-ROM
HD DVD-ROM
A DVD is an extremely high-capacity optical disc.
FIGURE 20
DVD-R
Y
Y
N
DVD
DVD+R
BD-R
HD DVD-R
DVD drive
DVD-RW
Y
Y
Y
DVD+RW
DVD+RAM
BD-RE
HD DVD-RW
FIGURE 21 Manufacturers sell CD-ROM and
DVD-ROM media prerecorded (written) with audio,
video, and software. Users cannot change the
contents of these discs. Users, however, can
purchase the other formats of CDs and DVDs as
blank media and record (write) their own data,
instructions, and information on these discs.
 
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