Computer storage is the internal or external storage areas in the computer. It comes in the forms of magnetic tapes/disks and optical medium, verses the computer memory which exists in chips or ICs (Integrated Circuits). Data storage not only can be installed/accessed internally/externally in the computer, but also as a detached component in the network for remote access bycomputers through the network.

There are two basic types of computer storage technologies:

Optical storage systems: it consists of a drive unit and a storage medium in a rotating disk form. In general the disks are pre-formatted using grooves and lands (tracks) to enable the positioning of an optical pick-up and recording head to access the information on the disk. Under the influence of a focused laser beam emanating from the optical head, information is recorded on the media as a change in the material characteristics, often using a thermally induced effect. To record a bit, a small spot is generated on the media modulating the phase, intensity, polarization, or reflectivity of a readout optical beam which is subsequently detected by a detector in the optical head. The disk media and the pick-up head are rotated and positioned through drive motors and servo systems controlling the position of the head with respect to data tracks on the disk. Additional peripheral electronics are used for control and data acquisition and encoding/decoding.

Magnetic storage systems: The magnetic recording medium, such as magnetic tape and hard drive, consists of a magnetic coating on some form of substrate. To record and play back the information one or more magnetic recording heads are used. The recording head consists of a high-permeability magnetic core with a narrow gap cut into it and a few turns of conductor wound around it. When current flows through the conductor, magnetic flux flows through the magnetic core, emanates from the core at the gap and penetrates the magnetic medium, causing it to be magnetized to the right or the left. Binary data are encoded in the form of transitions (ones) or the absence thereof (zeroes) in the magnetization in coincidence with a clock, which is synchronized with the disk or tape motion. A similar recording head is used to sense the magnetic flux emanating from the recorded transitions in the medium during read back.

Related Terms:Computer memory, Optical storage, Magnetic storage, Magnetic recording