Floppy disk

A floppy disk, also known as a floppy, diskette, or simply disk, is a type of disk storage composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic enclosure lined with fabric that removes dust particles. Floppy disks are read and written by a floppy disk drive (FDD).A simple example of a good design is the ​3 1⁄2-inch magnetic diskette for computers, a small circle of floppy magnetic material encased in hard plastic. Earlier types of floppy disks did not have this plastic case, which protects the magnetic material from abuse and damage. A sliding metal cover protects the delicate magnetic surface when the diskette is not in use and automatically opens when the diskette is inserted into the computer. The diskette has a square shape: there are apparently eight possible ways to insert it into the machine, only one of which is correct. What happens if I do it wrong? I try inserting the disk sideways. Ah, the designer thought of that. A little study shows that the case really isn't square: it's rectangular, so you can't insert a longer side. I try backward. The diskette goes in only part of the way. Small protrusions, indentations, and cutouts, prevent the diskette from being inserted backward or upside down: of the eight ways one might try to insert the diskette, only one is correct, and only that one will fit. An excellent design.IBM 33FD/Shugart 901IBM 43FD/Shugart 850IBM 53FD / Shugart 850500 KB (DS/DD)Marketed capacity is the capacity, typically unformatted, by the original media OEM vendor or in the case of IBM media, the first OEM thereafter. Other formats may get more or less capacity from the same drives and disks. A floppy disk, also known as a floppy, diskette, or simply disk, is a type of disk storage composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic enclosure lined with fabric that removes dust particles. Floppy disks are read and written by a floppy disk drive (FDD). Floppy disks, initially as 8-inch (203 mm) media and later in 5 1⁄4-inch (133 mm) and ​3 1⁄2 inch (90 mm) sizes, were a ubiquitous form of data storage and exchange from the mid-1970s into the first years of the 21st century. By 2006 computers were rarely manufactured with installed floppy disk drives; ​3 1⁄2-inch floppy disks can be used with an external USB floppy disk drive, but USB drives for ​5 1⁄4-inch, 8-inch, and non-standard diskettes are rare to non-existent. These formats are usually handled by older equipment. The prevalence of floppy disks in late-twentieth century culture was such that many electronic and software programs still use the floppy disks as save icons. 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, flash storage cards, portable external hard disk drives, optical discs, and cloud storage. The first commercial floppy disks, developed in the late 1960s, were 8 inches (200 mm) in diameter; they became commercially available in 1971 as a component of IBM products and then were sold separately beginning in 1972 by Memorex and others. These disks and associated drives were produced and improved upon by IBM and other companies such as Memorex, Shugart Associates, and Burroughs Corporation. The term 'floppy disk' appeared in print as early as 1970, and although IBM announced its first media as the 'Type 1 Diskette' in 1973, the industry continued to use the terms 'floppy disk' or 'floppy'. In 1976, Shugart Associates introduced the ​5 1⁄4-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, M2FM and GCR. The ​5 1⁄4-inch format displaced the 8-inch one for most applications, and the hard-sectored disk format disappeared. The most common capacity of the ​5 1⁄4-inch format in DOS-based PCs was 360 KB, for the DSDD (Double-Sided Double-Density) format using MFM encoding. In 1984 IBM introduced with its PC-AT model the 1.2 MB dual-sided ​5 1⁄4-inch floppy disk, but it never became very popular. IBM started using the 720 KB double-density ​3 1⁄2-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' (Double-Sided Extended-Density) diskettes in its top-of-the-line PS/2 models, but this was a commercial failure. Throughout the early 1980s, limitations of the ​5 1⁄4-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. A number of solutions were developed, with drives at 2-, ​2 1⁄2-, 3-, ​3 1⁄4-, ​3 1⁄2- and 4-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 (or, later, sometimes plastic) shutter 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 convenient than the adhesive tabs used with earlier disks. The large market share of the well-established ​5 1⁄4-inch format made it difficult for these diverse mutually-incompatible 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 ​3 1⁄2-inch was outselling the ​5 1⁄4-inch. Generally the term floppy disk persisted, even though later style floppy disks have a rigid case around an internal floppy disk. By the end of the 1980s, ​5 1⁄4-inch disks had been superseded by ​3 1⁄2-inch disks. During this time, PCs frequently came equipped with drives of both sizes. By the mid-1990s, ​5 1⁄4-inch drives had virtually disappeared, as the ​3 1⁄2-inch disk became the predominant floppy disk. The advantages of the ​3 1⁄2-inch disk were its higher capacity, its smaller size, and its rigid case which provided better protection from dirt and other environmental risks. If a person touches the exposed disk surface of a ​5 1⁄4-inch disk through the drive hole, fingerprints may foul the disk—and later the disk drive head if the disk is subsequently loaded into a drive—and it is also easily possible to damage a disk of this type by folding or creasing it, usually rendering it at least partly unreadable. However, largely due to its simpler construction (with no metal parts) the ​5 1⁄4-inch disk unit price was lower throughout its history, usually in the range of a third to a half that of a ​3 1⁄2-inch disk. Floppy disks became commonplace during the 1980s and 1990s in their use with personal computers to distribute software, transfer data, and create backups. Before hard disks became affordable to the general population, floppy disks were often used to store a computer's operating system (OS). Most home computers from that period have an elementary OS and BASIC stored in ROM, with the option of loading a more advanced operating system from a floppy disk.