Because a Cd-r Can Be Written on Only One Time, the Format of These Discs Sometimes Is Called ____?

Removable disk storage medium

viii-inch, five¼-inch, and 3½-inch floppy disks

viii-inch, v¼-inch (total height), and 3½-inch drives

A 3½-inch floppy deejay removed from its housing

A floppy deejay or floppy diskette (casually referred to as a floppy, or a diskette) is a type of deejay storage composed of a thin and flexible disk of a magnetic storage medium in a foursquare or most square plastic enclosure lined with a textile that removes dust particles from the spinning disk. Floppy disks shop digital information^{[nb i]} which tin can be read and written when the disk is inserted into a floppy disk drive (FDD) connected to or inside a estimator or other device.

The first floppy disks, invented and made past IBM, had a disk diameter of 8 inches (203.2 mm).^[1] Afterward the v¼-inch so the three½-inch became a ubiquitous course of information storage and transfer into the first years of the 21st century.^[ii] 3½-inch floppy disks tin can nonetheless exist used with an external USB floppy deejay drive. USB drives for 5¼-inch, eight-inch, and other-size floppy disks are rare to non-existent. Some individuals and organizations keep to apply older equipment to read or transfer data from floppy disks.

Floppy disks were and so common in late 20th-century culture that many electronic and software programs continue to use salve icons that expect similar floppy disks well into the 21st century. While floppy disk drives still have some limited uses, particularly with legacy industrial computer equipment, they have been superseded by data storage methods with much greater data storage chapters and information transfer speed, such every bit USB flash drives, memory cards, optical discs, and storage available through local estimator networks and deject storage.

History [edit]

8-inch floppy disk,
inserted in drive,
(3½-inch floppy diskette,
in front, shown for calibration)

iii½-inch, high-density floppy diskettes with adhesive labels affixed

The kickoff commercial floppy disks, developed in the belatedly 1960s, were 8 inches (203.two mm) in diameter;^{[1] [2]} they became commercially available in 1971 as a component of IBM products and and so were sold separately starting in 1972 past Memorex and others.^[iii] These disks and associated drives were produced and improved upon by IBM and other companies such as Memorex, Shugart Assembly, and Burroughs Corporation.^[4] The term "floppy disk" appeared in print as early as 1970,^[5] and although IBM announced its first media as the Type 1 Diskette in 1973, the industry continued to employ the terms "floppy disk" or "floppy".

In 1976, Shugart Associates introduced the 5¼-inch FDD. By 1978, in that location were more x manufacturers producing such FDDs.^[6] There were competing floppy disk formats, with difficult- and soft-sector versions and encoding schemes such as differential Manchester encoding (DM), modified frequency modulation (MFM), Chiliad²FM and group coded recording (GCR). The 5¼-inch format displaced the 8-inch one for nigh uses, and the hard-sectored disk format disappeared. The most common capacity of the 5¼-inch format in DOS-based PCs was 360 KB, for the Double-Sided Double-Density (DSDD) format using MFM encoding. In 1984, IBM introduced with its PC-AT model the 1.2 MB dual-sided 5¼-inch floppy disk, just it never became very popular. IBM started using the 720 KB double density 3½-inch microfloppy disk on its Convertible laptop computer in 1986 and the one.44 MB loftier-density version with the IBM Personal System/2 (PS/2) line in 1987. These disk drives could be added to older PC models. In 1988, IBM introduced a bulldoze for 2.88 MB Double-Sided Extended-Density (DSED) diskettes in its acme-of-the-line PS/ii models, but this was a commercial failure.

Throughout the early 1980s, limits of the 5¼-inch format became articulate. Originally designed to be more practical than the 8-inch format, it was condign considered too large; equally the quality of recording media grew, data could be stored in a smaller area.^[7] Several solutions were adult, with drives at ii-, 2½-, three-, 3¼-,^[viii] 3½- and 4-inches (and Sony's 90 mm × 94 mm (3.54 in × 3.70 in) disk) offered by various companies.^[7] They all had several advantages over the old format, including a rigid case with a sliding metallic (or later on, sometimes plastic) shutter over the head slot, which helped protect the delicate magnetic medium from grit and damage, and a sliding write protection tab, which was far more convenient than the adhesive tabs used with before disks. The large market share of the well-established 5¼-inch format fabricated it difficult for these diverse mutually-incompatible new formats to gain significant market share.^[7] A variant on the Sony design, introduced in 1982 by many manufacturers, was and so apace adopted. By 1988, the 3½-inch was outselling the v¼-inch.^[ix]

Generally, the term floppy disk persisted,^{[nb 2]} even though later fashion floppy disks have a rigid case around an internal floppy disk.

By the stop of the 1980s, v¼-inch disks had been superseded past three½-inch disks. During this time, PCs oft came equipped with drives of both sizes. By the mid-1990s, 5¼-inch drives had almost disappeared, as the 3½-inch disk became the predominant floppy disk. The advantages of the 3½-inch disk were its higher capacity, its smaller physical size, and its rigid case which provided improve protection from dirt and other environmental risks. If a person touches the exposed disk surface of a v¼-inch disk through the drive pigsty, fingerprints may foul the disk—and later the deejay drive head if the disk is subsequently loaded into a drive—and information technology is also easily possible to damage a disk of this type past folding or creasing it, usually rendering information technology at least partly unreadable. However, largely due to its simpler construction (with no metal parts) the 5¼-inch deejay unit of measurement price was lower throughout its history, usually in the range of a 3rd to a one-half that of a 3½-inch disk.^{[ citation needed ]}

Prevalence [edit]

Imation USB floppy bulldoze, model 01946: an external bulldoze that accepts high-density disks

Floppy disks became commonplace during the 1980s and 1990s in their use with personal computers to distribute software, transfer information, and create backups. Earlier difficult disks became affordable to the general population,^{[nb 3]} floppy disks were often used to store a computer's operating system (OS). Most home computers from that time have an unproblematic Bone and Basic stored in read-just retentivity (ROM), with the option of loading a more advanced OS from a floppy disk.

By the early 1990s, the increasing software size meant large packages similar Windows or Adobe Photoshop required a dozen disks or more than. In 1996, there were an estimated 5 billion standard floppy disks in utilize.^[10] And so, distribution of larger packages was gradually replaced by CD-ROMs, DVDs, and online distribution.

An attempt to enhance the existing 3½-inch designs was the SuperDisk in the belatedly 1990s, using very narrow data tracks and a loftier precision caput guidance mechanism with a capacity of 120 MB^[11] and astern-compatibility with standard 3½-inch floppies; a format war briefly occurred betwixt SuperDisk and other high-density floppy-deejay products, although ultimately recordable CDs/DVDs, solid-country flash storage, and eventually online storage would return all these removable disk formats obsolete. External USB-based floppy disk drives are still available, and many modern systems provide firmware support for booting from such drives.

Gradual transition to other formats [edit]

Front and rear of a retail three½-inch and five¼-inch floppy disk cleaning kit, as sold in Australia at retailer Large Due west, circa early 1990s

In the mid-1990s, mechanically incompatible higher-density floppy disks were introduced, similar the Iomega Nada deejay. Adoption was limited by the competition betwixt proprietary formats and the need to purchase expensive drives for computers where the disks would be used. In some cases, failure in marketplace penetration was exacerbated by the release of higher-capacity versions of the drive and media being not backward-compatible with the original drives, dividing the users between new and old adopters. Consumers were wary of making costly investments into unproven and rapidly changing technologies, so none of the technologies became the established standard.

Apple introduced the iMac G3 in 1998 with a CD-ROM drive simply no floppy bulldoze; this made USB-continued floppy drives popular accessories, equally the iMac came without any writable removable media device.

Recordable CDs were touted as an alternative, because of the greater capacity, compatibility with existing CD-ROM drives, and—with the appearance of re-writeable CDs and packet writing—a similar reusability as floppy disks. However, CD-R/RWs remained mostly an archival medium, non a medium for exchanging data or editing files on the medium itself, because there was no common standard for packet writing which allowed for pocket-size updates. Other formats, such as Magneto-optical discs, had the flexibility of floppy disks combined with greater chapters, but remained niche due to costs. High-capacity astern compatible floppy technologies became pop for a while and were sold every bit an pick or even included in standard PCs, merely in the long run, their employ was limited to professionals and enthusiasts.

Flash-based USB-thumb drives finally were a practical and popular replacement, that supported traditional file systems and all common usage scenarios of floppy disks. Every bit opposed to other solutions, no new bulldoze type or special software was required that impeded adoption, since all that was necessary was an already mutual USB port.

Use in the early on 21st century [edit]

By 2002, most manufacturers still provided floppy disk drives as standard equipment to run into user demand for file-transfer and an emergency boot device, as well as for the general secure feeling of having the familiar device.^[12] By this time, the retail cost of a floppy drive had fallen to around $20 (equivalent to $29 in 2020), and then there was little financial incentive to omit the device from a arrangement. Afterward, enabled by the widespread support for USB flash drives and BIOS boot, manufacturers and retailers progressively reduced the availability of floppy deejay drives as standard equipment. In Feb 2003, Dell, a leading computer visitor at the time, announced that floppy drives would no longer be pre-installed on Dell Dimension habitation computers, although they were yet available equally a selectable choice and purchasable as an aftermarket OEM addition.^[13] By Jan 2007, only ii% of computers sold in stores contained built-in floppy deejay drives.^[14]

Floppy disks are used for emergency boots in crumbling systems lacking support for other bootable media and for BIOS updates, since most BIOS and firmware programs can still exist executed from bootable floppy disks. If BIOS updates fail or become decadent, floppy drives tin sometimes be used to perform a recovery. The music and theatre industries notwithstanding use equipment requiring standard floppy disks (e.thou. synthesizers, samplers, drum machines, sequencers, and lighting consoles). Industrial automation equipment such as programmable machinery and industrial robots may not have a USB interface; data and programs are then loaded from disks, damageable in industrial environments. This equipment may non be replaced due to toll or requirement for continuous availability; existing software emulation and virtualization practise not solve this problem considering a customized operating system is used that has no drivers for USB devices. Hardware floppy disk emulators can be made to interface floppy-deejay controllers to a USB port that can exist used for wink drives.

In May 2016, the U.s.a. Government Accountability Role released a report that covered the demand to upgrade or supersede legacy estimator systems within federal agencies. According to this document, onetime IBM Serial/1 minicomputers running on 8-inch floppy disks are nonetheless used to coordinate "the operational functions of the The states' nuclear forces". The government planned to update some of the technology past the end of the 2022 fiscal year.^{[xv] [16]}

External USB floppy drives function as a USB mass storage device class. Windows 10 removed the commuter for internal floppy drives, which are a unlike device. External USB floppy drives continue to function.^[17]

The British Airways Boeing 747-400 fleet, up to its retirement in 2020, used 3.5-inch floppy disks to load avionics software.^[18]

Legacy [edit]

Screenshot depicting a floppy deejay every bit "save" icon

For more than two decades, the floppy disk was the master external writable storage device used. Most computing environments before the 1990s were non-networked, and floppy disks were the primary means to transfer data between computers, a method known informally as sneakernet. Dissimilar hard disks, floppy disks are handled and seen; even a novice user can identify a floppy disk. Because of these factors, a flick of a 3½-inch floppy disk became an interface metaphor for saving data. The floppy disk symbol is notwithstanding used by software on user-interface elements related to saving files, such as the release of Microsoft Office 2019, even though the physical floppy disks are largely obsolete, making information technology a skeuomorph.^[19]

Pattern [edit]

Structure [edit]

eight-inch and v¼-inch disks [edit]

Inside the 8-inch floppy disk

The 8-inch and 5¼-inch floppy disks incorporate a magnetically coated round plastic medium with a large circular pigsty in the centre for a drive's spindle. The medium is independent in a square plastic cover that has a pocket-size oblong opening in both sides to allow the drive's heads to read and write information and a large hole in the center to allow the magnetic medium to spin by rotating it from its eye hole.

Inside the embrace are two layers of fabric with the magnetic medium sandwiched in the middle. The fabric is designed to reduce friction betwixt the medium and the outer cover, and take hold of particles of debris abraded off the disk to proceed them from accumulating on the heads. The cover is ordinarily a ane-function sheet, double-folded with flaps glued or spot-welded together.

A small notch on the side of the disk identifies that it is writable, detected by a mechanical switch or phototransistor above information technology; if it is non present, the disk tin exist written; in the 8-inch disk the notch is covered to enable writing while in the 5¼-inch disk the notch is open to enable writing. Record may be used over the notch to modify the mode of the disk. Punch devices were sold to convert read-only disks to writable ones and enable writing on the unused side of unmarried sided disks; such modified disks became known as flippy disks.

Another LED/photograph-transistor pair located near the center of the deejay detects the index hole in one case per rotation in the magnetic disk; it is used to notice the angular offset of each runway and whether or not the disk is rotating at the correct speed. Early on viii‑inch and five¼‑inch disks had physical holes for each sector and were termed hard sectored disks. Later on soft-sectored disks have only one index hole, and sector position is determined by the disk controller or depression-level software from patterns marking the start of a sector. Mostly, the aforementioned drives are used to read and write both types of disks, with only the disks and controllers differing. Some operating systems using soft sectors, such every bit Apple DOS, practice not apply the index pigsty, and the drives designed for such systems oftentimes lack the corresponding sensor; this was mainly a hardware cost-saving measure.^[twenty]

three½-inch deejay [edit]

Rear side of a iii½-inch floppy disk in a transparent case, showing its internal parts

The core of the 3½-inch disk is the same every bit the other ii disks, but the forepart has merely a label and a small opening for reading and writing data, protected past the shutter—a jump-loaded metal or plastic cover, pushed to the side on entry into the drive. Rather than having a hole in the center, it has a metal hub which mates to the spindle of the bulldoze. Typical 3½-inch disk magnetic blanket materials are:^[21]

• DD: 2 μm magnetic iron oxide
• HD: 1.two μm cobalt-doped iron oxide
• ED: iii μm barium ferrite

2 holes at the lesser left and right indicate whether the disk is write-protected and whether information technology is high-density; these holes are spaced as far apart every bit the holes in punched A4 paper, allowing write-protected high-density floppies to be clipped into standard ring binders. The dimensions of the disk vanquish are not quite foursquare: its width is slightly less than its depth, and so that information technology is incommunicable to insert the disk into a drive slot sideways (i.east. rotated xc degrees from the correct shutter-first orientation). A diagonal notch at superlative right ensures that the disk is inserted into the bulldoze in the correct orientation—not upside downward or label-cease first—and an arrow at acme left indicates management of insertion. The bulldoze commonly has a button that, when pressed, ejects the deejay with varying degrees of forcefulness, the discrepancy due to the ejection force provided by the jump of the shutter. In IBM PC compatibles, Commodores, Apple tree Ii/IIIs, and other not-Apple-Macintosh machines with standard floppy disk drives, a disk may be ejected manually at any fourth dimension. The drive has a disk-change switch that detects when a disk is ejected or inserted. Failure of this mechanical switch is a common source of disk corruption if a disk is changed and the drive (and hence the operating arrangement) fails to detect.

One of the principal usability issues of the floppy disk is its vulnerability; even inside a closed plastic housing, the disk medium is highly sensitive to dust, condensation and temperature extremes. As with all magnetic storage, information technology is vulnerable to magnetic fields. Blank disks accept been distributed with an extensive gear up of warnings, cautioning the user not to expose it to dangerous weather condition. Rough treatment or removing the disk from the bulldoze while the magnetic media is withal spinning is likely to cause harm to the deejay, bulldoze head, or stored data. On the other hand, the three½‑inch floppy has been lauded for its mechanical usability by human–computer interaction expert Donald Norman:^[22]

A simple example of a good pattern is the 3½-inch magnetic diskette for computers, a modest circle of floppy magnetic fabric encased in hard plastic. Before types of floppy disks did non accept this plastic case, which protects the magnetic material from corruption and damage. A sliding metal comprehend protects the delicate magnetic surface when the diskette is not in employ 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 motorcar, but one of which is correct. What happens if I do it wrong? I attempt inserting the disk sideways. Ah, the designer thought of that. A little report shows that the case actually isn't square: it'southward rectangular, so you can't insert a longer side. I try astern. The diskette goes in just part of the fashion. Small protrusions, indentations, and cutouts prevent the diskette from existence inserted backward or upside downward: of the eight means one might try to insert the diskette, only one is right, and only that one volition fit. An splendid blueprint.

The spindle motor from a iii½‑inch unit

Operation [edit]

How the read-write head is practical on the floppy

Visualization of magnetic information on floppy deejay (image recorded with CMOS-MagView)

A spindle motor in the drive rotates the magnetic medium at a certain speed, while a stepper motor-operated machinery moves the magnetic read/write heads radially along the surface of the disk. Both read and write operations require the media to be rotating and the head to contact the disk media, an activeness originally achieved by a deejay-load solenoid.^[23] Later drives held the heads out of contact until a front-console lever was rotated (five¼-inch) or disk insertion was complete (3½-inch). To write information, current is sent through a coil in the caput as the media rotates. The head'south magnetic field aligns the magnetization of the particles directly below the head on the media. When the electric current is reversed the magnetization aligns in the opposite direction, encoding one chip of data. To read data, the magnetization of the particles in the media induce a tiny voltage in the caput curlicue as they pass under it. This small-scale bespeak is amplified and sent to the floppy disk controller, which converts the streams of pulses from the media into data, checks it for errors, and sends information technology to the host reckoner system.

Formatting [edit]

A blank unformatted diskette has a coating of magnetic oxide with no magnetic order to the particles. During formatting, the magnetizations of the particles are aligned forming tracks, each cleaved upwardly into sectors, enabling the controller to properly read and write data. The tracks are concentric rings around the center, with spaces between tracks where no data is written; gaps with padding bytes are provided between the sectors and at the end of the track to allow for slight speed variations in the disk drive, and to permit better interoperability with disk drives connected to other similar systems.

Each sector of information has a header that identifies the sector location on the disk. A cyclic back-up cheque (CRC) is written into the sector headers and at the cease of the user data so that the disk controller can detect potential errors.

Some errors are soft and can be resolved by automatically re-trying the read operation; other errors are permanent and the disk controller volition signal a failure to the operating system if multiple attempts to read the data nonetheless fail.

Insertion and ejection [edit]

After a disk is inserted, a catch or lever at the forepart of the bulldoze is manually lowered to prevent the deejay from accidentally emerging, engage the spindle clamping hub, and in two-sided drives, engage the second read/write caput with the media.

In some 5¼-inch drives, insertion of the disk compresses and locks an ejection spring which partially ejects the disk upon opening the catch or lever. This enables a smaller concave area for the thumb and fingers to grasp the disk during removal.

Newer 5¼-inch drives and all iii½-inch drives automatically engage the spindle and heads when a disk is inserted, doing the opposite with the press of the eject button.

On Apple Macintosh computers with built-in iii½-inch disk drives, the ejection button is replaced by software controlling an ejection motor which only does so when the operating organization no longer needs to access the drive. The user could elevate the prototype of the floppy bulldoze to the trash tin on the desktop to eject the disk. In the case of a ability failure or drive malfunction, a loaded disk tin be removed manually by inserting a straightened newspaper clip into a small hole at the drive's front console, merely equally one would do with a CD-ROM bulldoze in a similar situation. The Sharp X68000 featured soft-eject 5¼-inch drives. Some late-generation IBM PS/2 machines had soft-eject 3½-inch disk drives as well for which some problems of DOS (i.e. PC DOS 5.02 and college) offered an Squirt command.

Finding track cipher [edit]

Before a disk tin can be accessed, the bulldoze needs to synchronize its head position with the disk tracks. In some drives, this is achieved with a Track Naught Sensor, while for others it involves the drive head striking an immobile reference surface.

In either case, the head is moved and then that it is approaching track zero position of the disk. When a bulldoze with the sensor has reached runway zero, the caput stops moving immediately and is correctly aligned. For a drive without the sensor, the mechanism attempts to move the head the maximum possible number of positions needed to reach track zero, knowing that in one case this motion is consummate, the head will be positioned over rail naught.

Some drive mechanisms such equally the Apple tree II 5¼-inch drive without a rails null sensor, produce characteristic mechanical noises when trying to motility the heads past the reference surface. This physical striking is responsible for the 5¼-inch drive clicking during the boot of an Apple II, and the loud rattles of its DOS and ProDOS when disk errors occurred and track zip synchronization was attempted.

Finding sectors [edit]

All 8-inch and some 5¼-inch drives used a mechanical method to locate sectors, known as either difficult sectors or soft sectors, and is the purpose of the small pigsty in the jacket, off to the side of the spindle pigsty. A calorie-free beam sensor detects when a punched hole in the disk is visible through the pigsty in the jacket.

For a soft-sectored disk, at that place is simply a single pigsty, which is used to locate the commencement sector of each track. Clock timing is then used to find the other sectors behind information technology, which requires precise speed regulation of the drive motor.

For a hard-sectored deejay, there are many holes, one for each sector row, plus an additional pigsty in a half-sector position, that is used to bespeak sector zero.

The Apple Ii computer system is notable in that it did not have an index pigsty sensor and ignored the presence of hard or soft sectoring. Instead, it used special repeating information synchronization patterns written to the disk between each sector, to aid the figurer in finding and synchronizing with the data in each track.

The afterward iii½-inch drives of the mid-1980s did not apply sector index holes, but instead as well used synchronization patterns.

Most 3½-inch drives used a constant speed drive motor and contain the same number of sectors across all tracks. In order to fit more data onto a disk, some 3½-inch drives (notably the Macintosh External 400K and 800K drives) instead utilise variable speed drive motor than spins more slowly equally the caput moves away from the heart of the disk. This allows more sectors to be written to the longer middle and outer tracks equally the rails length increases.

Sizes [edit]

Unlike sizes of floppy disks are mechanically incompatible, and disks can fit only one size of drive. Drive assemblies with both 3+ 1⁄2 -inch and 5+ 1⁄iv -inch slots were available during the transition period betwixt the sizes, but they independent two separate drive mechanisms. In addition, in that location are many subtle, usually software-driven incompatibilities between the 2. 5+ 1⁄four -inch disks formatted for use with Apple Two computers would be unreadable and treated as unformatted on a Commodore. Every bit computer platforms began to form, attempts were made at interchangeability. For case, the "SuperDrive" included from the Macintosh SE to the Power Macintosh G3 could read, write and format IBM PC format 3+ one⁄ii -inch disks, but few IBM-compatible computers had drives that did the contrary. 8-inch, 5+ 1⁄four -inch and 3+ i⁄ii -inch drives were manufactured in a diverseness of sizes, most to fit standardized drive bays. Alongside the common deejay sizes were not-classical sizes for specialized systems.

8-inch floppy deejay [edit]

Floppy disks of the first standard are eight inches in diameter,^[ane] protected by a flexible plastic jacket. It was a read-just device used past IBM every bit a mode of loading microcode.^[24] Read/write floppy disks and their drives became available in 1972, but it was IBM's 1973 introduction of the 3740 data entry organisation^[25] that began the establishment of floppy disks, called by IBM the Diskette 1, every bit an industry standard for information interchange. Formatted diskette for this organization store 242,944 bytes.^[26] Early on microcomputers used for engineering, business organization, or give-and-take processing often used one or more 8-inch disk drives for removable storage; the CP/Yard operating system was developed for microcomputers with 8-inch drives.

The family of 8-inch disks and drives increased over fourth dimension and later versions could store up to 1.two MB;^[27] many microcomputer applications did non need that much capacity on 1 disk, and so a smaller size disk with lower-cost media and drives was viable. The 5+ 1⁄4 -inch bulldoze succeeded the viii-inch size in many applications, and developed to about the same storage chapters equally the original viii-inch size, using college-density media and recording techniques.

five+ ane⁄4 -inch floppy disk [edit]

five¼-inch floppies, front and back

Uncovered

5+ one⁄4 ‑inch disk machinery with disk inserted.

The head gap of an 80‑runway high-density (1.2 MB in the MFM format) 5+ 1⁄four ‑inch bulldoze (a.k.a. Mini diskette, Mini disk, or Minifloppy) is smaller than that of a 40‑track double-density (360 KB if double-sided) drive but can likewise format, read and write 40‑track disks provided the controller supports double stepping or has a switch to do and so. v+ i⁄4 -inch 80-track drives were also called hyper drives.^{[nb 4]} A blank 40‑track disk formatted and written on an lxxx‑runway drive can exist taken to its native bulldoze without problems, and a disk formatted on a twoscore‑rails drive tin be used on an 80‑rails bulldoze. Disks written on a 40‑rails drive and and so updated on an 80 track drive become unreadable on whatsoever 40‑rails drives due to track width incompatibility.

Unmarried-sided disks were coated on both sides, despite the availability of more expensive double sided disks. The reason normally given for the higher price was that double sided disks were certified error-free on both sides of the media. Double-sided disks could be used in some drives for single-sided disks, as long equally an index bespeak was not needed. This was done one side at a time, past turning them over (flippy disks); more expensive dual-head drives which could read both sides without turning over were later produced, and eventually became used universally.

three+ 1⁄2 -inch floppy disk [edit]

Internal parts of a

three+ i⁄ii -inch floppy deejay.

1. A pigsty that indicates a high-capacity deejay.
2. The hub that engages with the drive motor.
3. A shutter that protects the surface when removed from the bulldoze.
4. The plastic housing.
5. A polyester sail reducing friction confronting the disk media as it rotates within the housing.
6. The magnetic coated plastic disk.
7. A schematic representation of one sector of data on the disk; the tracks and sectors are not visible on actual disks.
8. The write protection tab (unlabeled) in upper left.

A

three+ 1⁄two -inch floppy disk bulldoze

In the early 1980s, many manufacturers introduced smaller floppy drives and media in various formats. A consortium of 21 companies somewhen settled on a iii+ i⁄2 -inch pattern known as the Micro diskette, Micro disk, or Micro floppy, like to a Sony blueprint but improved to support both single-sided and double-sided media, with formatted capacities generally of 360 KB and 720 KB respectively. Single-sided drives shipped in 1983,^[28] and double-sided in 1984. The double-sided, high-density 1.44 MB (actually 1440 KiB) disk drive, which would become the most popular, first shipped in 1986.^[29] The first Macintosh computers used single-sided 3+ ane⁄ii -inch floppy disks, but with 400 KB formatted capacity. These were followed in 1986 by double-sided 800 KB floppies. The higher capacity was achieved at the same recording density by varying the disk-rotation speed with head position so that the linear speed of the deejay was closer to constant. Later Macs could as well read and write 1.44 MB Hard disk disks in PC format with fixed rotation speed. Higher capacities were similarly achieved by Acorn's RISC OS (800 KB for DD, 1,600 KB Hard disk drive) and AmigaOS (880 KB).

All 3+ one⁄2 -inch disks take a rectangular hole in one corner which, if obstructed, write-enables the deejay. A sliding detented piece can be moved to block or reveal the part of the rectangular hole that is sensed by the drive. The HD 1.44 MB disks accept a 2nd, unobstructed hole in the opposite corner that identifies them as being of that capacity.

In IBM-compatible PCs, the three densities of 3+ 1⁄2 -inch floppy disks are backwards-uniform; higher-density drives can read, write and format lower-density media. Information technology is also possible to format a deejay at a lower density than that for which it was intended, only but if the disk is first thoroughly demagnetized with a bulk eraser, as the high-density format is magnetically stronger and volition prevent the disk from working in lower-density modes.

Writing at dissimilar densities than those at which disks were intended, sometimes past altering or drilling holes, was possible but not supported by manufacturers. A hole on one side of a 3+ 1⁄two -inch disk can be contradistinct as to make some deejay drives and operating systems treat the deejay as one of higher or lower density, for bidirectional compatibility or economical reasons.^{[ description needed ] [30] [31]} Some computers, such equally the PS/2 and Acorn Archimedes, ignored these holes altogether.^[32]

Other sizes [edit]

Other smaller, floppy sizes were proposed, peculiarly for portable or pocket-sized devices that needed a smaller storage device. 3¼-inch floppies otherwise similar to 5¼-inch floppies were proposed by Tabor and Dysan. Three-inch disks like in construction to 3½-inch were manufactured and used for a time, particularly by Amstrad computers and discussion processors. A ii-inch nominal size known every bit the Video Floppy was introduced by Sony for apply with its Mavica notwithstanding video camera.^[33] An incompatible ii-inch floppy produced by Fujifilm chosen the LT-1 was used in the Zenith Minisport portable computer.^[34] Neither of these sizes achieved much market success.^[35]

Sizes, operation and capacity [edit]

Floppy disk size is often referred to in inches, even in countries using metric and though the size is defined in metric. The ANSI specification of 3+ 1⁄2 -inch disks is entitled in role "90 mm (three.5-inch)" though 90 mm is closer to 3.54 inches.^[36] Formatted capacities are more often than not set in terms of kilobytes and megabytes.

Historical sequence of floppy disk formats

Disk format	Twelvemonth introduced	Formatted storage capacity	Marketed capacity
8-inch: IBM 23FD (read-simply)	1971	81.664 kB[37]	non marketed commercially
eight-inch: Memorex 650	1972	175 kB[38]	1.v megabit full rail[38]
viii-inch: SSSD IBM 33FD/Shugart 901	1973	242.844 kB[37]	3.1 megabit unformatted
8-inch: DSSD IBM 43FD/Shugart 850	1976	568.320 kB[37]	6.2 megabit unformatted
5+ ane⁄four -inch (35 track) Shugart SA 400	1976[39]	87.5 KB[twoscore]	110 kB
8-inch DSDD IBM 53FD / Shugart 850	1977	985–1,212 KB depending upon sector size	1.2 MB
v+ one⁄iv -inch DD	1978	360 or 800 KB	360 KB
5+ i⁄four -inch Apple Disk Ii (Pre-DOS 3.3)	1978	113.75 KB (256 byte sectors, 13 sectors/rail, 35 tracks)	113 KB
five+ 1⁄4 -inch Atari DOS 2.0S	1979	90 KB (128 byte sectors, 18 sectors/track, twoscore tracks)	90 KB
5+ 1⁄4 -inch Commodore DOS 1.0 (SSDD)	1979[41]	172.v KB[42]	170 KB
5+ ane⁄iv -inch Commodore DOS 2.ane (SSDD)	1980[43]	170.75 KB[42]	170 KB
5+ 1⁄4 -inch Apple tree Disk II (DOS iii.3)	1980	140 KB (256 byte sectors, 16 sectors/track, 35 tracks)	140 KB
5+ 1⁄4 -inch Apple Disk Two (Roland Gustafsson'due south RWTS18)	1988	157.v KB (768 byte sectors, six sectors/track, 35 tracks)	Game publishers privately contracted tertiary party custom DOS.
3+ i⁄ii -inch HP single sided	1982	256×16×70 = 280 KB	264 KB
5+ 1⁄4 -inch Atari DOS iii	1983	127 KB (128 byte sectors, 26 sectors/track, 40 tracks)	130 KB
iii-inch	1982[44] [45]	?	125 KB (SS/SD), 500 KB (DS/DD)[45]
iii+ 1⁄two -inch SS (DD at release)	1983	360 KB (400 on Macintosh)	500 KB
3+ 1⁄2 -inch DS DD	1983	720 KB (800 KB on Macintosh and RISC OS,[46] 880 KB on Amiga)	1 MB
5+ 1⁄four -inch QD		720 KB	720 KB
v+ 1⁄4 -inch RX50 (SSQD)	circa 1982	400 KB[ commendation needed ]	400 KB
5+ one⁄iv -inch HD	1982[47]	1,200 KB (1,600 KB on RISC OS[46])	1.2 MB
3-inch DD[ citation needed ]	?	?	?
iii-inch Mitsumi Quick Deejay	1985	128 to 256 KB	?
ii-inch	1989	720 KB[48]	?
two+ i⁄2 -inch Sharp CE-1600F,[49] CE-140F (chassis: FDU-250, medium: CE-1650F)[50]	1986[49] [50] [51]	turnable diskette with 62,464 bytes per side (512 byte sectors, 8 sectors/runway, sixteen tracks, GCR (iv/5) recording)[49] [50]	2× 64 KB (128 KB)[49] [50]
v+ 1⁄four -inch[52] Perpendicular	1986[51]	100 KB per inch[51]	?
3+ one⁄2 -inch Hd	1986[53]	1,440 KB (1,760 KB on Amiga)	1.44 MB (2.0 MB unformatted)
iii+ 1⁄2 -inch Famicom Disk System	1986		128 KB[54]
3½-inch ED	1987[55]	two,880 KB (three,200 KB on Sinclair QL)	2.88 MB
3+ 1⁄two -inch Floptical (LS)	1991	twenty,385 KB	21 MB
3+ ane⁄2 -inch SuperDisk (LS-120)	1996	120.375 MB	120 MB
3+ 1⁄2 -inch SuperDisk (LS-240)	1997	240.75 MB	240 MB
three+ ane⁄2 -inch HiFD	1998/99	?	150/200 MB
Abbreviations: SD = Unmarried Density; DD = Double Density; QD = Quad Density; Hd = High Density; ED = Extra-high Density; [56] [57] [58] [59] [60] LS = Laser Servo; HiFD = High capacity Floppy Disk; SS = Single Sided; DS = Double Sided
Formatted storage capacity is total size of all sectors on the deejay: For viii-inch see List of floppy disk formats#IBM 8-inch formats. Spare, hidden and otherwise reserved sectors are included in this number. For 5+ i⁄4 - and three+ 1⁄2 inch capacities quoted are from subsystem or arrangement vendor statements. Marketed capacity is the chapters, typically unformatted, by the original media OEM vendor or in the case of IBM media, the first OEM thereafter. Other formats may get more than or less capacity from the same drives and disks.

A box of about fourscore floppy disks together with one USB memory stick. The stick is capable of holding over 130 times as much data every bit the entire box of disks put together.

Information is generally written to floppy disks in sectors (angular blocks) and tracks (concentric rings at a constant radius). For example, the Hard disk format of 3½-inch floppy disks uses 512 bytes per sector, 18 sectors per rails, lxxx tracks per side and two sides, for a total of 1,474,560 bytes per disk.^{[61] [ failed verification ]} Some disk controllers can vary these parameters at the user's asking, increasing storage on the disk, although they may non exist able to be read on machines with other controllers. For case, Microsoft applications were often distributed on 3+ i⁄two -inch 1.68 MB DMF disks formatted with 21 sectors instead of xviii; they could still be recognized by a standard controller. On the IBM PC, MSX and about other microcomputer platforms, disks were written using a constant angular velocity (CAV) format,^[55] with the disk spinning at a constant speed and the sectors property the same amount of information on each track regardless of radial location.

Because the sectors take abiding angular size, the 512 bytes in each sector are compressed more well-nigh the deejay's center. A more space-efficient technique would be to increment the number of sectors per runway toward the outer edge of the disk, from 18 to 30 for instance, thereby keeping nearly constant the amount of physical disk space used for storing each sector; an case is zone bit recording. Apple implemented this in early on Macintosh computers by spinning the deejay more slowly when the caput was at the edge, while maintaining the information rate, allowing 400 KB of storage per side and an extra eighty KB on a double-sided disk.^[62] This higher capacity came with a disadvantage: the format used a unique drive machinery and command circuitry, significant that Mac disks could non exist read on other computers. Apple eventually reverted to constant angular velocity on HD floppy disks with their afterward machines, still unique to Apple tree as they supported the older variable-speed formats.

Disk formatting is normally done past a utility program supplied by the figurer OS manufacturer; generally, it sets upwards a file storage directory organization on the disk, and initializes its sectors and tracks. Areas of the disk unusable for storage due to flaws can be locked (marked as "bad sectors") and so that the operating arrangement does not endeavour to use them. This was time-consuming then many environments had quick formatting which skipped the error checking process. When floppy disks were often used, disks pre-formatted for popular computers were sold. The unformatted capacity of a floppy deejay does non include the sector and rails headings of a formatted disk; the difference in storage between them depends on the drive's application. Floppy disk drive and media manufacturers specify the unformatted capacity (for example, 2 MB for a standard 3+ 1⁄two -inch Hard disk floppy). It is implied that this should not exist exceeded, since doing so volition nigh likely upshot in performance bug. DMF was introduced permitting 1.68 MB to fit onto an otherwise standard 3+ 1⁄2 -inch disk; utilities then appeared assuasive disks to be formatted as such.

Mixtures of decimal prefixes and binary sector sizes crave care to properly calculate total capacity. Whereas semiconductor memory naturally favors powers of ii (size doubles each time an address pivot is added to the integrated circuit), the capacity of a disk drive is the product of sector size, sectors per rail, tracks per side and sides (which in hard disk drives with multiple platters can exist greater than 2). Although other sector sizes accept been known in the by, formatted sector sizes are at present almost always set to powers of ii (256 bytes, 512 bytes, etc.), and, in some cases, deejay capacity is calculated as multiples of the sector size rather than just in bytes, leading to a combination of decimal multiples of sectors and binary sector sizes. For instance, ane.44 MB iii+ 1⁄2 -inch Hd disks have the "M" prefix peculiar to their context, coming from their capacity of 2,880 512-byte sectors (1,440 KiB), consequent with neither a decimal megabyte nor a binary mebibyte (MiB). Hence, these disks hold ane.47 MB or 1.41 MiB. Usable data chapters is a office of the deejay format used, which in turn is determined past the FDD controller and its settings. Differences between such formats can result in capacities ranging from approximately 1300 to 1760 KiB (one.fourscore MB) on a standard 3+ 1⁄2 -inch high-density floppy (and upwards to virtually 2 MB with utilities such as 2M/2MGUI). The highest capacity techniques require much tighter matching of drive head geometry between drives, something not always possible and unreliable. For case, the LS-240 drive supports a 32 MB chapters on standard 3+ 1⁄two -inch Hard disk drive disks,^[63] simply this is a write-in one case technique, and requires its own bulldoze.

The raw maximum transfer rate of 3+ 1⁄2 -inch ED floppy drives (2.88 MB) is nominally one,000 kilobits/s, or approximately 83% that of single-speed CD‑ROM (71% of audio CD). This represents the speed of raw information bits moving under the read head; yet, the constructive speed is somewhat less due to space used for headers, gaps and other format fields and can be even further reduced by delays to seek between tracks.

Meet likewise [edit]

• Berg connector for 3½-inch floppy drive
• dd (Unix)
• Disk paradigm
• Don't Copy That Floppy
• Floppy disk controller
• Floppy disk hardware emulator
• Floppy deejay variants
• Hard disk drive
• History of the floppy disk
• Shugart motorbus – popular mainly for 8-inch drives, and partially for 5¼-inch
• XDF
• VGA-Copy copy tool (retries on errors, over-formatted floppies), DOS, discontinued
• Zero drive

Notes [edit]

1. ^ An exception was the Sony Mavica camera.
2. ^ However, chosen "stiffy" in South Africa.
3. ^ The cost of a hd with a controller in the mid 1980s was thousands of dollars, for capacity of lxxx MB or less.
4. ^ "Hyper drive" was an alternative name for v¼-inch 80-track HD floppy drives with 1.2 MB capacity. The term was used f.e. by Philips Austria for their Philips :YES and Digital Research in conjunction with DOS Plus.

References [edit]

1. ^ ^{a b c} Teja, Edward R. (1985). The Designer's Guide to Disk Drives (1st ed.). Reston, Virginia, Usa: Reston Publishing Company, Inc. / Prentice-Hall Company. ISBN0-8359-1268-X.
2. ^ ^{a b} Fletcher, Richard (2007-01-30). "PC Earth Announces the Finish of the Floppy Deejay". The Daily Telegraph. Archived from the original on 2012-01-02. Retrieved 2020-08-02 .
3. ^ "1971: Floppy deejay loads mainframe computer data". Computer History Museum. Computer History Museum. Archived from the original on 2015-12-08. Retrieved 2015-12-01 .
4. ^ "Five decades of disk drive industry firsts". Archived from the original on 2011-07-26. Retrieved 2012-10-fifteen .
5. ^ IBM's 370/145 Uncovered; Interesting Curves Revealed, Datamation, November i, 1970
6. ^ Watson (2010-05-24). "The Floppy Disk". Canadian Business organization. Vol. 83, no. 8. p. 17.
7. ^ ^{a b c} "The Microfloppy—One Key to Portability", Thomas R. Jarrett, Calculator Technology Review, winter 1983 (Jan 1984), pp. 245–7
8. ^ Pic of disk
9. ^ 1991 Deejay/Trend Report, Flexible Disk Drives, Figure 2
10. ^ Reinhardt, Andy (1996-08-12). "Iomega's Zip drives demand a bit more than zip". Business Week. No. 33. The McGraw-Hill Companies. ISSN 0007-7135. Archived from the original on 2008-07-06.
11. ^ "floppy". LinuxCommand.org. 2006-01-04. Archived from the original on 2011-07-27. Retrieved 2011-06-22 .
12. ^ Bound, Tom (2002-07-24). "What Has Your Floppy Drive Done for You Lately? PC makers are still standing by floppy drives despite vanishing consumer demand". PC World. Archived from the original on 2011-12-24. Retrieved 2012-04-04 .
13. ^ "R.I.P. Floppy Disk". BBC News. 2003-04-01. Archived from the original on 2009-02-xvi. Retrieved 2011-07-xix .
14. ^ Derbyshire, David (2007-01-30). "Floppy disks ejected as need slumps". The Daily Telegraph. Archived from the original on 2011-05-22. Retrieved 2011-07-19 .
15. ^ "Federal Agencies Need to Address Crumbling Legacy Systems" (PDF). Study to Congressional Requesters. U.s.a. Authorities Accountability Office. May 2016. Archived (PDF) from the original on 2016-06-02. Retrieved 2016-05-26 .
16. ^ Trujillo, Mario (2016-05-25). "US nuclear emergency messaging system still uses floppy disks". The Hill. Archived from the original on 2016-05-29. Retrieved 2016-05-30 .
17. ^ "How to employ Floppy Disk on Windows 10". 2016-03-09. Archived from the original on 2018-11-17. Retrieved 2019-06-11 .
18. ^ Warren, Tom (August xi, 2020). "Boeing 747s still get critical updates via floppy disks: A rare expect inside a 20-year-old airliner". The Verge. Phonation Media. Retrieved 2021-02-26 .
19. ^ Landphair, Ted (2007-03-10). "So Long, Faithful Floppies". VOA News. Vocalisation of America. Archived from the original on Oct 10, 2016. Retrieved 2008-12-25 .
20. ^ "The Disk II". Apple tree II History. 2008-12-02. Archived from the original on 2018-02-xix. Retrieved 2018-02-17 . Wozniak's technique would allow the drive to do cocky-synchronization ("soft sectoring"), not have to bargain with that lilliputian timing pigsty, and save on hardware.
21. ^ (M)Tronics SCS (2007-05-20). "Floppy-Disketten-Laufwerke" [Floppy disk drives] (in German). Archived from the original on 2017-06-19. Retrieved 2017-06-19 .
22. ^ Norman, Donald (1990). "Chapter 1". The Pattern of Everyday Things. New York, USA: Doubleday. ISBN0-385-26774-half dozen.
23. ^ Porter, Jim, ed. (2005). "Oral History Console on eight inch Floppy Disk Drives" (PDF). p. 4. Archived from the original (PDF) on 2015-05-13. Retrieved 2011-06-22 .
24. ^ "Floppy Deejay". Louisiana State University. Archived from the original on 2014-10-18. Retrieved 2013-12-02 .
25. ^ "IBM Athenaeum: IBM 3740". www-03.ibm.com. 23 Jan 2003. Archived from the original on 25 December 2017. Retrieved xiii October 2014.
26. ^ IBM 3740 Data Entry Arrangement System Summary and Installation Manual – Physical Planning (PDF). IBM. 1974. p. 2. Archived (PDF) from the original on 2017-02-15. Retrieved 2019-03-07 . The diskette is virtually 8" (20 cm) foursquare and has a internet capacity of 1898 128-grapheme records – virtually ane 24-hour interval's data entry activity. Each of the diskette'south 73 magnetic recording tracks available for data entry can concord 26 sectors of up to 128 characters each.
27. ^ "The IBM Diskette General Information Manual". Archived from the original on 2014-10-28. Retrieved 2014-10-13 .
28. ^ Shea, Tom (1983-06-13). "Shrinking drives increase storage". InfoWorld. pp. i, vii, 8, 9, 11. Shugart is one of the major subscribers to the 3+ ane⁄2 -inch micro-floppy standard, forth with Sony and 20 other company ... Its single-sided SA300 micro-floppy drive offers 500K of unformatted storage. Shugart's Kevin Burr said the obvious adjacent pace is to put another 500K of storage on the other side of the diskette and that the house will come up out with a double-sided 1-megabyte micro-floppy drive soon.
29. ^ 1986 Disk/Tendency Study - Flexible Disk Drives. Disk/Tendency, Inc. Nov 1986. p. FSPEC-59. Reports Sony shipped in 1Q 1986
30. ^ "Managing Disks". Archived from the original on 2006-05-24. Retrieved 2006-05-25 .
31. ^ "A question of floppies". Archived from the original on 2011-ten-01. Retrieved 2011-02-xx .
32. ^ "Formatting 720K Disks on a ane.44MB Floppy". Floppy Drive. Archived from the original on 2011-07-23. Retrieved 2011-02-11 .
33. ^ "Sony / Canon 2 Inch Video Floppy". Museum of Obsolete Media. 2013-05-02. Archived from the original on 13 January 2018. Retrieved 4 January 2018.
34. ^ "ii inch lt1 floppy disk". Museum of Obsolete Media. 2017-07-22. Archived from the original on iv Jan 2018. Retrieved 4 January 2018.
35. ^ Disk/Tendency Report-Flexible Disk Drives, Disk/Trend Inc., November 1991, pp. SUM-27
36. ^ ANSI X3.137, One- and Two-Sided, Unformatted, ninety-mm (3.5-inch) 5,3-tpmm (135-tpi), Flexible Deejay Cartridge for 7958 bpr Utilize. Full general, Physical and Magnetic Requirements.
37. ^ ^{a b c} Engh, James T. (September 1981). "The IBM Diskette and Diskette Drive". IBM Journal of Research and Development. 25 (5): 701–710. doi:10.1147/rd.255.0701.
38. ^ ^{a b} "Memorex 650 Flexible Disc File" (PDF). Archived from the original (PDF) on 2011-07-25. Retrieved 2011-06-22 .
39. ^ Sollman, George (July 1978). "Evolution of the Minifloppy Product Family". IEEE Transactions on Magnetics. xiv (4): 160–66. doi:10.1109/TMAG.1978.1059748. ISSN 0018-9464. S2CID 32505773.
40. ^ "Shugart SA 400 Datasheet". Swtpc. 2007-06-25. Archived from the original on 2014-05-27. Retrieved 2011-06-22 .
41. ^ Beals, Gene (n.d.). "New Commodore Products: A Quick Review" (PDF). PET User Notes. Vol. 2, no. one. Montgomeryville, Pennsylvania. p. 2. Archived (PDF) from the original on 2016-06-11. Retrieved 2018-10-07 .
42. ^ ^{a b} W, Raeto Collin (Jan 1982). Programming the PET/CBM: The Reference Encyclopedia For Commodore PET & CBM Users. COMPUTE! Books. p. 167. ISBN0-942386-04-3 . Retrieved 2018-10-07 .
43. ^ Commodore Concern Machines (1980-02-05). "cbmsrc / DOS_4040 / dos". GitHub . Retrieved 2018-10-07 .
44. ^ "Chronology of Events in the History of Microcomputers − 1981–1983 Business Takes Over". Archived from the original on 2008-12-07. Retrieved 2008-10-04 .
45. ^ ^{a b} "Three-inch floppy disk product announced" (PDF). Archived from the original (PDF) on 2012-08-08. Retrieved 2008-10-04 .
46. ^ ^{a b} "six. Using floppy and hard discs". RISC Os 3.7 User Guide. January 21, 1997. Retrieved January 4, 2022.
47. ^ 1986 Deejay/Trend Report, Flexible Disk Drives
48. ^ "Viability of 2-Inch Media Standard for PCs in Doubt". InfoWorld. 11 (31): 21. 1989-07-31.
49. ^ ^{a b c d} "Model CE-1600F" (PDF). Precipitous PC-1600 Service Manual. Yamatokoriyama, Nihon: Precipitous Corporation, Information Systems Group, Quality & Reliability Control Center. July 1986. pp. 98–104. Archived (PDF) from the original on 2017-03-23. Retrieved 2017-03-12 .
50. ^ ^{a b c d} Sharp Service Manual Model CE-140F Pocket Deejay Drive (PDF). Abrupt Corporation. 00ZCE140F/SME. Archived (PDF) from the original on 2017-03-11. Retrieved 2017-03-11 .
51. ^ ^{a b c} Bateman, Selby (March 1986). "The Future of Mass Storage". COMPUTE!. No. 70. COMPUTE! Publications, Inc. p. 18. Archived from the original on 2018-07-01. Retrieved 2018-ten-07 .
52. ^ JP S6344319A, Kitagami, Osamu & Fujiwara, Hideo, "Production of perpendicular magnetic recording medium", published 1988-02-25, assigned to Hitachi Maxell
53. ^ "Vendor Introduces Ultra High-Density Floppy Disk Media". InfoWorld. 8 (45): 19. 1986-11-10.
54. ^ "Revisiting the Famicom Disk Organisation". Eurogamer. 27 July 2019. {{cite spider web}}: CS1 maint: url-status (link)
55. ^ ^{a b} Mueller, Scott (2004). Upgrading and Repairing PCs, 15th Anniversary Edition. Que Publishing. p. 1380. ISBN0-7897-2974-1 . Retrieved 2011-07-16 .
56. ^ Mueller, Scott (1994). Hardware-Praxis – PCs warten reparieren, aufrüsten und konfigurieren (in German) (3rd ed.). Addison-Wesley Publishing Company. p. 441. ISBN3-89319-705-2.
57. ^ Inc, InfoWorld Media Group (fourteen October 1991). "InfoWorld". InfoWorld Media Group, Inc. – via Google Books.
58. ^ Shah, Katen A. (1996) [September 1992, April 1992]. Intel 82077SL for Super-Dense Floppies (PDF) (Awarding Note) (2 ed.). Intel Corporation, IMD Marketing. AP-358, 292093-002. Archived (PDF) from the original on 2017-06-nineteen. Retrieved 2017-06-19 .
59. ^ Inc, Ziff Davis (10 September 1991). "PC Mag". Ziff Davis, Inc. – via Google Books.
60. ^ Inc, InfoWorld Media Group (19 March 1990). "InfoWorld". InfoWorld Media Group, Inc. – via Google Books.
61. ^ "Chapter 8: Floppy Disk Drives" (PDF). Archived (PDF) from the original on 2012-01-27. Retrieved 2011-07-16 .
62. ^ "The Original Macintosh". Archived from the original on 2013-12-05. Retrieved 2013-12-03 .
63. ^ "Properties of Storage Systems". Mt. San Antonio College. Archived from the original on 2013-12-07.

Further reading [edit]

• Weyhrich, Steven (2005). "The Disk II": A detailed essay describing one of the first commercial floppy disk drives (from the Apple tree Ii History website).
• Immers, Richard; Neufeld, Gerald G. (1984). Inside Commodore DOS: The Complete Guide to the 1541 Disk Operating System. Datamost & Reston Publishing Visitor (Prentice-Hall). ISBN 0-8359-3091-two.
• Englisch, Lothar; Szczepanowski, Norbert (1984). The Anatomy of the 1541 Deejay Bulldoze. Grand Rapids, Michigan, Usa, Abacus Software (translated from the original 1983 German edition, Düsseldorf, Data Becker GmbH). ISBN 0-916439-01-ane.
• Hewlett Packard: 9121D/South Disc Memory Operator's Manual; printed ane September 1982; office number 09121-90000.

External links [edit]

Wikimedia Eatables has media related to Diskette.

• HowStuffWorks: How Floppy Disk Drives Work
• Figurer Promise: Information about computer floppy drives
• NCITS (mention of ANSI X3.162 and X3.171 floppy standards)
• Floppy deejay drives and media technical information
• The Floppy User Guide -historical technical material
• Summary of Floppy Disk Types and Specifications

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Source: https://en.wikipedia.org/wiki/Flexible_disk

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