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Magnetic Storage DevicesMagnetic Storage Devices - Magnetic Tape - Storage Devices - Magnetic Storage - Magnets - Storage Media - Tape DrivesThe diskette drives, tape drives and hard disk drives are examples of magnetic storage devices. These devices are used to write and read data to and from the diskettes, tapes and hard disks. The surfaces of diskette, tape and hard disk are coated with magnetic material such as iron oxide or ferrous oxide, which can be magnetized (i.e. which reacts to a magnetic field). The surfaces of disks and magnetic tapes are coated with millions of tiny iron particles so that data can be stored on them. Each of these particles can act as a magnet. The write/read heads of disk drives or tape drives contain electromagnets that generate magnetic fields in the iron on the storage medium as the head passes over the disk or tape. The presence of a magnetic field represents a ‘1’ bit and its absence represents a ‘0’ bit. The data reading process from magnetic disk or tape is reversed. In reading process, no current is flowing through the electromagnetic and read/write heads have no magnetic field. Because the storage medium has a magnetic field but the head does not. The storage medium charges the magnet in the head, which causes a small current to flow through the head in one direction or the other depending on the polarity of the field. The disk or tape drive senses the direction of the flow as the disk or tape passes by the head. In this way data is sent from the read/write head into memory in the form of electric pulses. The information stored in a disk can be read many times without affecting the stored data. So the reading operation is non-destructive. But the writing of new data erases data previously stored at that location of the disk or tape. Magnetic Disk Now-a-days, magnetic disk is commonly used in computers as secondary storage. A magnetic disk is a circular metal or plastic disk coated on both sides with magnetic recording material (ferrous oxide). The data on magnetic disk is recorded as magnetic fields. The data and instructions are accessed directly or randomly. The disk drives are used to write and read data. The data is stored both sides of the disk (i.e. side 0 and side 1), and each side has its own read/ write head. The magnetic disks are available with different types. There are two fundamental types of magnetic disks. i) Floppy disk or interchangeable disk ii) Hard disk or fixed disk See Also or Related Articles:
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