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(a) Front view of a floppy disk drive.
Opening for inserting the disk inside the drive
Floppy disk eject button
Write-protect plastic tab
Sliding metal piece cover
User's label for identification (b) A 31/2-inch floppy disk
All 3'/2-inch floppy disks are of double-sided type and record data on both the disk
surfaces. However, they come in three different capacities - double density, high density,
and very high density. The double-density 3'/2-inch diskettes have 40 tracks, 18
sectors/track, and 512 bytes/sector, giving a total disk storage capacity of 2 (for two
surfaces) x40x 18x512 = 7,37,280 bytes = 720 KB (approximately). The high-density
31//2-inch diskettes have 80 tracks, 18 sectors/track, and 512 bytes/sector, giving a total
disk storage capacity of 2 x 80 x 18 x 512 = 14,74,560 bytes =1.4 MB (approximately).
The, very high-density 3'/2-inch diskettes have 80 tracks, 36 sectors/track, and 512
bytes/sector, giving a total disk storage capacity of 2 x 80 x 36 x 512 = 29,49,120 bytes =
2.88 MB (approximately).
Figure 8.21 summarizes the capacities of the various types of 5'/4-inch and 3'/2-inch
diskettes. Note that a smaller size disk can actually have more storage capacity than a
larger size disk. Because of their hard-plastic jacket cover and the sliding metal cover
over the aperture, the 3/4-inch floppy disks are more durable. The 3'/2-inch diskettes are
slowly replacing the 5'A-inch diskettes because of their better durability, compact size
(which can easily fit in a shirt's pocket), and higher capacity. As a result, the 5%-inch
floppy disks are gradually disappearing.
of No. of No.
of Capacity in Approximate
surfaces tracks sectors/track bytes/sector bytes
of the capacities of the various types 3,68,640
of 5%-inch 360 KB
and 3 1/4-inch Note that the capacities given in Figure 8.21 are for DOS-based computers. As discussed
before, different make...
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- Spring '14