Hard Disk: A hard disk, also called a hard disk drive, is a storage device that contains one or more inflexible, circular patterns that magnetically store data, instructions, and information.
As with foppy disks, the data on hard disks is recorded on a series of tracks located on one or more platters. The tracks are divided into sectors when the disk is formatted. In view of above Figure show how a hard drive works.
The hard Drive platters spin at a high rate of speed, typically 5,400 to 7,200 revolutions per minute. When reading data from the disk, the read head senses the magnetic spots that are recorded on the disk along the various tracks and transfers that data to memory. When writing, the data is transferred from memory and is stored as magnetic spots on the tracks on the recording surface of one or more of the disk platters. When reading or writing, the read / write heads on a hard disk drive do not actually touch the surface of the disk.
The number of platters permanently mounted on the spindle of hard disk varies. On most drives, each surface of the platter can be used to store data. Thus, if a hard disk drive uses one platter, two surfaces are available for data. If the drive uses two platters, four sets of read / write heads read and record data from the four surfaces. Storage capacity of internally mounted fixed disks for personal computers range from 10 GB to more than 200 GB.
The system unit on most destop and notebook computers contains at least one hard disk. Although hard disks are available in removable cartridge form, most hard disks cannot be removed from the computer.
prepared by: Younis.
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