Unlike a diskette, a hard disk is rigid and fixed in place. It is sealed in a protective case to keep it free from dust and dirt. A hard disk stores data the same way that a diskette does, but it works faster and has a much larger storage capacity.

All disks are divided into data storage compartments by sides, tracks, and sectors. Double-sided diskettes-like the ones you use in your computer-store data on both sides. On your disk there are concentric rings, called tracks, in which a disk can store data. Double-density diskettes (such as 360KB diskettes) have 40 tracks, and high-density diskettes (such as 1.2MB diskettes) have 80 tracks.

A hard disk consists of two or more magnetically-coated platters stacked on top of one another, so it has four or more sides with many more tracks than a diskette.

A disk is further divided by sectors. To understand what a sector is, picture the spokes on a bicycle wheel radiating from the center of the wheel to the tire. The space between one spoke and the next is like a sector on a diskette. (See the figure below.) Each track on a 1.2MB diskette has 15 sectors, and each sector holds 512 bytes.

Using Your Computer

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