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A floppy disk, also called a diskette or just disk, is a type of disk storage composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles. Floppy disks are read and written by a floppy disk drive (FDD). Floppy disks, initially as media and later in 5¼-inch (133 mm) and 3½-inch (90 mm) sizes, were a ubiquitous form of data storage and exchange from the mid-1970s well into the 2000s. By 2010, computer motherboards are rarely manufactured with floppy drive support; 3½-inch floppy disks can be used with an external USB floppy disk drive, but USB drives for 5¼-inch, 8-inch, and non-standard diskettes are rare to non-existent. These formats are usually handled by older equipment. While floppy disk drives still have some limited uses, especially with legacy industrial computer equipment, they have been superseded by data storage methods with much greater capacity, such as USB flash drives, portable external hard disk drives, optical discs, memory storage cards and computer networks. == History == (詳細はIBM and other companies such as Memorex, Shugart Associates, and Burroughs Corporation. The term "floppy disk" appeared in print as early as 1970,〔IBM's 370/145 Uncovered; Interesting Curves Revealed, Datamation, November 1, 1970〕 and although in 1973 IBM announced its first media as "Type 1 Diskette" the industry continued to use the terms "floppy disk" or "floppy". In 1976, Shugart Associates introduced the first 5¼-inch FDD. By 1978 there were more than 10 manufacturers producing such FDDs. There were competing floppy disk formats, with hard- and soft-sector versions and encoding schemes such as FM, MFM and GCR. The 5¼-inch format displaced the 8-inch one for most applications, and the hard-sectored disk format disappeared. In 1984, IBM introduced the 1.2 MB dual-sided floppy disk along with its AT model. IBM started using the 720 KB double-density 3½-inch microfloppy disk on its Convertible laptop computer in 1986 and the 1.44 MB high-density version with the PS/2 line in 1987. These disk drives could be added to older PC models. In 1988 IBM introduced a drive for 2.88 MB "DSED" diskettes in its top-of-the-line PS/2 models, but this was a commercial failure. Throughout the early 1980s, limitations of the 5¼-inch format became clear. Originally designed to be more practical than the 8-inch format, it was itself too large; as the quality of recording media grew, data could be stored in a smaller area.〔"The Microfloppy—One Key to Portability", Thomas R. Jarrett, Computer Technology Review, winter 1983 (Jan 1984), pp 245–7〕 A number of solutions were developed, with drives at 2, 2½, 3 and 3½ inches (and Sony's 90.0 mm × 94.0 mm disk) offered by various companies.〔 They all shared a number of advantages over the old format, including a rigid case with a sliding metal cover over the head slot, which helped protect the delicate magnetic medium from dust and damage, and a sliding write protection tab, which was far more practical than the adhesive tabs used with earlier disks. The large market share of the 5¼-inch format made it difficult for these new formats to gain significant market share.〔 A variant on the Sony design, introduced in 1982 by a large number of manufacturers, was then rapidly adopted; by 1988 the 3½-inch was outselling the 5¼-inch.〔1991 Disk/Trend Report, Flexible Disk Drives, Figure 2〕 By the end of the 1980s, 5¼-inch disks had been superseded by 3½-inch disks. By the mid-1990s, 5¼-inch drives had virtually disappeared, as the 3½-inch disk became the predominant floppy disk. The advantages of the 3½-inch disk were its smaller size and its plastic case, which provided better protection from dirt and other environmental risks, while the 5¼-inch disk was available cheaper per piece throughout its history, usually with a price in the range of 1/3 to 2/3 of a 3½-inch disk. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Floppy disk」の詳細全文を読む スポンサード リンク
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