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PublisherChapter 6. Floppy Disk Drives
The following four chapters cover
standard floppy disk drives, high-capacity
"super" floppy disk drive
replacements, removable hard drives, and tape drives, all of which
are characterized as removable magnetic storage devices. These
devices use media that can be swapped in and out of the drive, versus
hard disk drives, whose media are a fixed part of the drives
themselves. Although they are typically slower at accessing data than
hard diskssometimes much slowerremovable magnetic
storage devices are useful because you can store an unlimited amount
of data on additional cartridges, albeit with only a subset of the
data available online at any one time. Because media are separate
items, you can transfer data between computers that are not
networked, if those computers are equipped with a compatible drive.
Removable media also allow storing data off-site as protection
against fire, theft, or other
catastrophes.
A major drawback of removable magnetic storage is inherent: magnetic
storage is less reliable than optical storage. Over time, zero bits
and one bits stored as magnetic domains tend to become an unreadable
blur. A less obvious drawback of magnetic versus optical storage is
the proprietary nature of most magnetic drives and media, and the
continually changing standards. Try, for example, to read data
written only five years ago to a proprietary DC600 tape drive. The
original drive is dead, the manufacturer no longer exists, and the
software used to write the data won't run on
anything later than Windows 3.1 anyway. Even something as simple as
reading data from a 5.25-inch floppy diskette can turn into a major
undertaking. Accordingly, the most appropriate uses of these drives
are to provide supplemental working storage, to transfer large
amounts of data between computers, and to make backups. They are
unsuitable for long-term data archiving.Removable magnetic storage devices differ in many respects, including
drive cost, storage capacity, and access time. Perhaps the most
important difference is the cost of media, both per cartridge and per
megabyte stored. When selecting a removable magnetic storage device,
always keep in mind that media cost over the service life of the
drive may greatly exceed the cost of the drive itself, particularly
for drives that use proprietary, patented, and/or licensed media.
Many of these drives are marketed on the King Gillette model of
giving away the razor and selling the blades. The cost of those
blades can really add up.A floppy disk drive (FDD)
is so called because it records data on a flexible circular plastic
disk coated with ferrite or some other magnetic medium. This plastic
disk is enclosed within a protective sleeve or cartridge. This
assembly is called a floppy disk or a
diskette. FDDs have been manufactured to accept
8-, 5.25-, and 3.5-inch diskettes, although only the last is still in
common use.
