Because of their hard plastic jacket cover and the

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Unformatted text preview: e) (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. Size (Diameter in inches) 5'/4 5% VA VA VA Figure 8.21. diskettes. No. of No. of No. of No. of Capacity in Approximate surfaces tracks sectors/track bytes/sector bytes capacity 2 2 2 2 2 Summary 40 9 512 80 15 512 40 18 512 80 18 512 80 36 512 of the capacities of the various types 3,68,640 12,28,800 7,37,280 14,74,560 29,49,120 of 5%-inch 360 KB 1.2 MB 720 KB 1.4 MB 2.88 MB 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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