Chapter 10. CD-ROM Drives
CD-ROM
drives are so standardized and ubiquitous that, excepting high-end
SCSI models, they have become commoditized. If you use a CD-ROM drive
only to play audio CDs, load software, and so on, nearly any recent
CD-ROM drive suffices. If you need to replace a failed drive or buy a
drive for a new PC, you can use an inexpensive ATAPI CD-ROM
drive—while they remain available—or you can substitute
an ATAPI DVD-ROM drive, which also reads CDs. If you put more demands
on a drive, such as accessing databases, playing games directly from
CD, or using the drive as a source to duplicate CDs,
it's worth learning about the differences between
currently available drives.
This chapter and the following chapter cover standard CD-ROM drives,
CD-Recordable (CD-R)
drives, and CD-Rewritable (CD-RW) drives, all of which store data on
optical discs.
Most drive manufacturers other than Seagate use the spelling
"disk" for drives that use magnetic
storage. By convention, all manufacturers use the spelling
"disc" for drives that accept
optical media.
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Many people are careful about the clear side of optical discs, but
take less care with the label side. In fact, the clear side is a
tough, protective polycarbonate layer. Data actually resides on a
thin aluminum substrate immediately beneath the label. Because the
label is very fragile, it is the label side that deserves careful
handling.
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Commercially produced discs record data as a series
of microscopic pits and lands physically embossed on an aluminum
substrate. Optical drives use a low-power laser to read data from
those discs without physical contact between the head and the disc,
which contributes to the high reliability and permanence of optical
storage. Write-capable optical drives use higher-power lasers to
record data on special discs. CD-Recordable (CD-R) records data
permanently to the disc, and is also called Write-Once. CD-Rewritable
(CD-RW) allows data that has been written to be erased or
over-written, and is also called Write-Many.
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