Magnetic storage hard disk drives

Hard disk magnetic storage hard drives consist of rigid circular disks with diameters that range between about 65 mm (2.5 in.) and 95 mm (3.75 in). During read and... 

Information storage is accomplished by using magnetic materials the two principal types of magnetic media are hard disk drives and magnetic tapes. 

The storage medium for hard disk drives is composed of nanometer-size grains of an HCP cobalt-chromium alloy. These grains are oriented snch that their direction of easy magnetization (i.e., [0001]) is perpendicnlar to the plane of the disk. 

There is no competitive situation for data storage disks with embossed iaformation (CD-ROM) and recordable/nonerasable disks (WORM) no counterpart to CD-ROM and WORM exists among magnetic memories. EOD drives are best compared to floppies and removable hard disk media given their possibiUty of easy and problem-free disk exchange and a capacity on the order of that of removable magnetic media (Tape, Bernoulli, SyQuest). 

Early versions of home computers also had magnetic tape drives as a secondary method of data storage. In the 1970 s, IBM offered their own version of a magnetic cassette tape recorder (compatible with its desktop computer) that used the widely available cassette tape. By 1985, however, hard disks and floppy disks had dominated the market for computer systems designed to access smaller amounts of data frequently and quickly, and cassette tapes became obsolete for home-computer data storage. 

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