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Diskette
A floppy disk or floppy diskette (casually referred to as a floppy, a diskette, or a disk) is a type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a fabric that removes dust particles from the spinning disk. The three most popular (and commercially available) floppy disks are the 8-inch, 5¼-inch, and 3½-inch floppy disks. Floppy disks store digital data which can be read and written when the disk is inserted into a floppy disk drive (FDD) connected to or inside a computer or other device. The first floppy disks, invented and made by IBM in 1971, had a disk diameter of . Subsequently, the 5¼-inch (133.35 mm) and then the 3½-inch (88.9 mm) became a ubiquitous form of data storage and transfer into the first years of the 21st century. 3½-inch floppy disks can still be used with an external USB floppy disk drive. USB drives for 5¼-inch, 8-inch, and other-size floppy disks are rare t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Floppy Disk Variants
The floppy disk is a data storage and transfer medium that was ubiquitous from the mid-1970s well into the 2000s. Besides the 3½-inch and 5¼-inch formats used in IBM PC compatible systems, or the 8-inch format that preceded them, many proprietary floppy disk formats were developed, either using a different disk design or special layout and encoding methods for the data held on the disk. Non-standard media and devices IBM DemiDiskette In the early 1980s, IBM Rochester developed a 4-inch floppy disk drive, the Model 341 and an associated diskette, the DemiDiskette. At about half the size of the original 8-inch floppy disk the name derived from the prefix ''demi'' for "half". This program was driven by aggressive cost goals, but missed the pulse of the industry. The prospective users, both inside and outside IBM, preferred standardization to what by release time were small cost reductions, and were unwilling to retool packaging, interface chips and applications for a prop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM Personal Computer/AT
The IBM Personal Computer AT (model 5170, abbreviated as IBM AT or PC/AT) was released in 1984 as the fourth model in the IBM Personal Computer line, following the IBM PC/XT and its IBM Portable PC variant. It was designed around the Intel 80286 microprocessor. Name IBM did not specify an expanded form of ''AT'' on the machine, press releases, brochures or documentation, but some sources expand the term as ''Advanced Technology'', including at least one internal IBM document. History IBM's 1984 introduction of the AT was seen as an unusual move for the company, which typically waited for competitors to release new products before producing its own models. At $4,000–6,000, it was only slightly more expensive than considerably slower IBM models. The announcement surprised rival executives, who admitted that matching IBM's prices would be difficult. No major competitor showed a comparable computer at COMDEX Las Vegas that year. Features The AT is IBM PC compatible, wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Double Density
Disk density is a capacity designation on magnetic storage, usually floppy disks. Each designation describes a set of characteristics that can affect the areal density of a disk or the efficiency of the encoded data. Such characteristics include modulation method, track width, coercivity, and magnetic field direction. 8-inch media ''Single density'' (SD or 1D) describes the first generation of floppy disks that use an iron oxide coating. Floppy drives utilize 300-oersted write heads, FM encoding, and a track width of for a density of 48 tracks-per-inch (tpi) and 5,876 bits-per-inch (bpi). ''Double density'' (DD or 2D) doubles capacity over SD by replacing FM encoding with an improved line code, such as modified frequency modulation (MFM), modified modified frequency modulation (M²FM), FM/MFM or group coded recording (GCR). 5¼-inch media ''SD'' (''1D'') and ''DD'' (''2D'') designations were generally identical to those of 8-inch disks. ''Quad density'' (QD or 4D) d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-density Storage Media
Disk density is a capacity designation on magnetic storage, usually floppy disks. Each designation describes a set of characteristics that can affect the areal density of a disk or the efficiency of the encoded data. Such characteristics include modulation method, track width, coercivity, and magnetic field direction. 8-inch media ''Single density'' (SD or 1D) describes the first generation of floppy disks that use an iron oxide coating. Floppy drives utilize 300-oersted write heads, FM encoding, and a track width of for a density of 48 tracks-per-inch (tpi) and 5,876 bits-per-inch (bpi). ''Double density'' (DD or 2D) doubles capacity over SD by replacing FM encoding with an improved line code, such as modified frequency modulation (MFM), modified modified frequency modulation (M²FM), FM/MFM or group coded recording (GCR). 5¼-inch media ''SD'' (''1D'') and ''DD'' (''2D'') designations were generally identical to those of 8-inch disks. ''Quad density'' (QD or 4D) dou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shugart Associates
Shugart Associates (later Shugart Corporation) was a computer peripheral manufacturer that dominated the floppy disk drive market in the late 1970s and is famous for introducing the -inch "Minifloppy" floppy disk drive. In 1979 it was one of the first companies to introduce a hard disk drive form factor compatible with a floppy disk drive, the SA1000 form factor compatible with the 8-inch floppy drive form factor. Founded in 1973, Shugart Associates was purchased in 1977 by Xerox, which then exited the business in 1985 and 1986, selling the brand name and the 8-inch floppy product line (in March 1986) to Narlinger Group, which ultimately ceased operations circa 1991. History Beginnings After a distinguished career at IBM and a few years at Memorex, Alan Shugart decided to strike out on his own in 1973. After gathering venture capital, he started Shugart Associates. The original business plan was to build a small-business system (similar to the IBM 3740) dealing with the developm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Floppy Disk Format
Floppy disk format and density refer to the physical and logical layout of data stored on a floppy disk. Since their introduction, there have been many floppy disk types, densities, and formats, popular and rare, used in computing, leading to much confusion over their differences. In the early 2000s, most floppy disk types and formats became obsolete, leaving the -inch disk, using an IBM PC compatible format of 1440 KiB, as the only remaining popular format. Different floppy disk types have different recording characteristics, with varying magnetic coercivity (measured in oersteds, or in modern SI units in amperes per meter), ferrite grain size, and tracks per inch (TPI). TPI was not a part of the physical manufacturing process; it was a certification of how closely tracks of data could be spaced on the medium safely. The term density has a double meaning for floppy disks. Originally, single density and double density indicated a difference in logical encoding on the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burroughs Corporation
The Burroughs Corporation was a major American manufacturer of business equipment. The company was founded in 1886 as the American Arithmometer Company by William Seward Burroughs I, William Seward Burroughs. The company's history paralleled many of the major developments in history of computing, computing. At its start, it produced mechanical adding machines, and later moved into programmable ledgers and then computers. It was one of the largest producers of mainframe computers in the world, also producing related equipment including typewriters and Printer (computing), printers. In the 1960s, the company introduced a range of mainframe computers that were well regarded for their performance running high level languages. These formed the core of the company's business into the 1970s. At that time the emergence of superminicomputers and the dominance of the IBM System/360 and 370 at the high end led to shrinking markets, and in 1986 the company purchased former competitor Sperry C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM PC Convertible
The IBM PC Convertible (model 5140) is a laptop computer made by IBM, first sold in April 1986. The Convertible was IBM's first laptop-style computer, following the luggable IBM Portable, and introduced the 3½-inch floppy disk format to the IBM product line. Like modern laptops, it featured power management and the ability to run from batteries. It was replaced in 1991 by the IBM PS/2 L40 SX, and in Japan by the IBM Personal System/55note, the predecessor to the ThinkPad. Predecessors IBM had been working on a laptop for some time before the Convertible. In 1983, work was underway on a laptop similar to the Tandy Model 100, codenamed "Sweetpea", but it was rejected by Don Estridge for not being PC compatible. Another attempt in 1984 produced the "P-14" prototype machine, but it failed to pass IBM's human factors tests, especially after poor public reception of the display in the competing Data General-One. Description The PC Convertible came in three models: PC Converti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
