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Introduction - Chapter 1

About Your Hard Disk

Your hard disk allows you to store, use and retrieve large amounts of data quickly and conveniently. Information is stored on spinning disks or "platters" located within the hard drive. Unlike floppy disks, these platters cannot be removed and are protected from the wear and tear of being handled.

Hard disk platters, like floppy disks, are usually either 3.5 or 5.25 inches in diameter, and are coated with a magnetic recording surface that records information on both sides. A hard disk usually contains from one to eight platters. The platters spin continuously while the computer is powered on.

In order for the computer to locate information quickly on the hard disk, the platters are divided into smaller sections. Each hard disk platter is organized into cylinders, tracks, and sectors.

Sectors are the smallest unit of storage on the hard disk platter, usually 512 bytes.

Tracks are similar to the tracks on a record album. They divide the hard disk platter into concentric circles. A track is made up of several sectors.

A cylinder on a single hard disk platter is the recording space on both the top and bottom of one track. A cylinder on a multiple-platter hard disk is the recording space (top and bottom) on all of the platters of the tracks with the same track number.

The hard disk finds information by using the combination of three numbers-cylinder, track and sector - to find the desired block. It is similar to the city, street, and box number on a mailing address.

Information stored on the hard disk platter is read and written by read/write heads. A read7write head is like the head of a cassette tape deck, but moves across the surface on an arm similar to the tone arm of a record player. To read or write data, the head senses and discharges magnetic impulses at the appropriate cylinder as the rotating platter passes beneath it. There is a separate head for each surface (top and bottom) of each hard disk platter.

There are many types of hard drives, with varying storage sizes from 20MB (20 megabytes, or over 20 million characters) to more than 100MB of information. A 20 MB hard drive has about as much storage space as 26 standard Amiga 3.5-inch floppy disks. This is the equivalent of nearly 5,700 typed pages.

Amiga - supplied hard disks come with at least one partition - the Workbench (or System). Depending on which computer you own, you may have received additional partitions, such as a Work partition provides as general storage space.

With the HDToolBox program, you can re-partition your hard disk in any way you like, giving each partition any name otherwise unused.

The best time to partition a hard disk is before you begin using it. All information on affected partitions (for example, a large partition you may have separated into two smaller ones) is erased in the process. If you already have important information stored on affected partitions, you must back up the information and restore it after you partition.

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