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107-501: The Disk II Floppy Disk Subsystem , often rendered as Disk ][ , is a 5 + 1 ⁄ 4 -inch floppy disk drive designed by Steve Wozniak at the recommendation of Mike Markkula , and manufactured by Apple Computer It went on sale in June 1978 at a retail price of US$ 495 for pre-order; it was later sold for $ 595 (equivalent to $ 2,780 in 2023) including the controller card (which can control up to two drives) and cable. The Disk II

214-439: 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

321-400: A transmission medium or data storage medium . The most common physical channels are: Some of the more common binary line codes include: Each line code has advantages and disadvantages. Line codes are chosen to meet one or more of the following criteria: Most long-distance communication channels cannot reliably transport a DC component . The DC component is also called the disparity ,

428-549: A DOS, and with Wozniak inexperienced in operating system design, Steve Jobs approached Shepardson Microsystems with the project. On April 10, 1978 Apple signed a contract for $ 13,000 with Shepardson to develop the DOS. Shortly after the disk drive project began in late 1977, Steve Jobs made several trips to Shugart's offices announcing that he wanted a disk drive that would cost just $ 100. After Wozniak finished studying IBM disk controller designs, Jobs then demanded that Shugart sell them

535-476: A Macintosh to read from or write to 5 + 1 ⁄ 4 -inch Apple II-formatted disks. This drive was made obsolete by the industry-wide adoption of 3 + 1 ⁄ 2 -inch disks and was replaced by the 3 + 1 ⁄ 2 -inch Apple FDHD Drive , which could read and write every existing Macintosh, DOS and Windows format, and the Apple II ProDOS format as well. This table shows the pinout of

642-514: A black painted case, which matched the color of the Bell & Howell version of the Apple II Plus, which Apple was already manufacturing. In 1978, Apple intended to develop its own " FileWare " drive mechanism for use in the new Apple /// and Lisa business computers then being developed. They quickly ran into difficulties with the mechanisms, which precluded them from being incorporated in

749-514: A built-in drive mechanism. The Apple III Plus changed its 26-pin connector to a DB-25 connector, which required an adapter for use with the Disk III. In 1983, Apple finally announced a single and dual external drive ( UniFile and DuoFile ) implementing the 871-kilobyte " FileWare " mechanism used in the original Apple Lisa , as a replacement for the Disk II & /// drives. However, due to

856-443: A button that, when pressed, ejects the disk with varying degrees of force, the discrepancy due to the ejection force provided by the spring of the shutter. In IBM PC compatibles , Commodores, Apple II/IIIs, and other non-Apple-Macintosh machines with standard floppy disk drives, a disk may be ejected manually at any time. The drive has a disk-change switch that detects when a disk is ejected or inserted. Failure of this mechanical switch

963-650: A customized operating system is used that has no drivers for USB devices. Hardware floppy disk emulators can be made to interface floppy-disk controllers to a USB port that can be used for flash drives. In May 2016, the United States Government Accountability Office released a report that covered the need to upgrade or replace legacy computer systems within federal agencies. According to this document, old IBM Series/1 minicomputers running on 8-inch floppy disks are still used to coordinate "the operational functions of

1070-428: A disk can be accessed, the drive needs to synchronize its head position with the disk tracks. In some drives, this is accomplished with a Track Zero Sensor, while for others it involves the drive head striking an immobile reference surface. In either case, the head is moved so that it is approaching track zero position of the disk. When a drive with the sensor has reached track zero, the head stops moving immediately and

1177-474: A disk, some 3½-inch drives (notably the Macintosh External 400K and 800K drives ) instead use Constant Linear Velocity (CLV), which uses a variable speed drive motor that spins more slowly as the head moves away from the center of the disk, maintaining the same speed of the head(s) relative to the surface(s) of the disk. This allows more sectors to be written to the longer middle and outer tracks as

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1284-544: A drive system for the computer after finding that a checkbook-balancing program Markkula had written took too long to load from tape. Wozniak knew nothing about disk controllers , but while at Hewlett-Packard he had designed a simple, five-chip circuit to operate a Shugart Associates drive. The Apple II's lack of a disk drive was "a glaring weakness" in what was otherwise intended to be a polished, professional product. Speaking later, Osborne 1 designer Lee Felsenstein stated, "The difference between cassette and disk systems

1391-413: A hard-sectored disk, there are many holes, one for each sector row, plus an additional hole in a half-sector position, that is used to indicate sector zero. The Apple II computer system is notable in that it did not have an index hole sensor and ignored the presence of hard or soft sectoring. Instead, it used special repeating data synchronization patterns written to the disk between each sector, to assist

1498-420: A loaded disk can be removed manually by inserting a straightened paper clip into a small hole at the drive's front panel, just as one would do with a CD-ROM drive in a similar situation. The X68000 has soft-eject 5¼-inch drives. Some late-generation IBM PS/2 machines had soft-eject 3½-inch disk drives as well for which some issues of DOS (i.e. PC DOS 5.02 and higher) offered an EJECT command. Before

1605-527: A much larger installed base. For these reasons the 3 + 1 ⁄ 2 -inch format was not widely accepted by Apple II users. The Apple 3.5 Drive used the same 800-kilobyte format as the UniDisk 3.5", but it did away with the internal controller, which made it cheaper. Unlike all earlier Apple II drives, it was designed to work with the Macintosh too, and among Apple II models, it was compatible only with

1712-557: A recovery. The music and theatre industries still use equipment requiring standard floppy disks (e.g. 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 not be replaced due to cost or requirement for continuous availability; existing software emulation and virtualization do not solve this problem because

1819-468: A selectable option and purchasable as an aftermarket OEM add-on. By January 2007, only 2% of computers sold in stores contained built-in floppy disk drives. Floppy disks are used for emergency boots in aging systems lacking support for other bootable media and for BIOS updates, since most BIOS and firmware programs can still be executed from bootable floppy disks . If BIOS updates fail or become corrupt, floppy drives can sometimes be used to perform

1926-505: A single hole in the rotating floppy disk medium line up. This mechanism is used to detect the angular start of each track, and whether or not the disk is rotating at the correct speed. Early 8‑inch and 5¼‑inch disks also had holes for each sector in the enclosed magnetic medium, in addition to the index hole, with the same radial distance from the center, for alignment with the same envelope hole. These were termed hard sectored disks. Later soft- sectored disks have only one index hole in

2033-447: 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

2140-411: A small oblong opening in both sides to allow the drive's heads to read and write data and a large hole in the center to allow the magnetic medium to spin by rotating it from its middle hole. Inside the cover are two layers of fabric with the magnetic medium sandwiched in the middle. The fabric is designed to reduce friction between the medium and the outer cover, and catch particles of debris abraded off

2247-640: A stripped disk drive that had no controller board, index sensor, load solenoids , or track zero sensor. Although puzzled by this request, Shugart complied and provided Apple with 25 drive mechanisms that they could use as prototypes in developing a disk system for the Apple II. The prototypes received the designation of SA-390. Wozniak studied North Star Computers and others' more complex floppy controllers. He believed that his simpler design lacked their features, but realized that they were less sophisticated; for example, his could use soft-sectored disks. Following

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2354-475: Is a common source of disk corruption if a disk is changed and the drive (and hence the operating system) fails to notice. One of the chief usability problems 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 , it is vulnerable to magnetic fields. Blank disks have been distributed with an extensive set of warnings, cautioning

2461-400: 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 once this motion is complete, the head will be positioned over track zero. Some drive mechanisms such as the Apple II 5¼-inch drive without a track zero sensor, produce characteristic mechanical noises when trying to move

2568-437: Is difficult; if they are too short, the high frequencies might be attenuated by the communications channel. By modulating the data , RLL reduces the timing uncertainty in decoding the stored data, which would lead to the possible erroneous insertion or removal of bits when reading the data back. This mechanism ensures that the boundaries between bits can always be accurately found (preventing bit slip ), while efficiently using

2675-485: Is not the case with Apple's 3 + 1 ⁄ 2 -inch drives, which use several different disk formats and several different interfaces, electronically quite dissimilar even in models using the same connector; they are not generally interchangeable. Apple did not originally offer a disk drive for the Apple II, which used data cassette storage like other microcomputers of the time. Apple early investor and executive Mike Markkula asked cofounder Steve Wozniak to design

2782-428: Is still used by software on user-interface elements related to saving files even though physical floppy disks are largely obsolete. Examples of such software include LibreOffice , Microsoft Paint , and WordPad . The 8-inch and 5¼-inch floppy disks contain a magnetically coated round plastic medium with a large circular hole in the center for a drive's spindle. The medium is contained in a square plastic cover that has

2889-535: The 5 + 1 ⁄ 4 -inch Disk II format drives continued to be offered alongside the newer 3 + 1 ⁄ 2 -inch drives and remained the standard on the non-IIGS models until the platform was discontinued in 1993. Officially, the following 3 + 1 ⁄ 2 -inch drives could be used on the Apple II: The 400-kilobyte and 800-kilobyte Macintosh external drives (M0130 and M0131) are incompatible with standard Apple II controllers as they do not support

2996-629: The Apple IIGS and the Apple IIc+ models, which both had a faster main CPU. On the Apple IIGS, whose improved audiovisual capacities really demanded a higher-capacity disk format as well, the 3 + 1 ⁄ 2 -inch format was accepted by users and became the standard format. Though Apple eventually offered a 1.44-megabyte SuperDrive with matching controller card for the Apple II series as well,

3103-526: The Apple PC 5.25" Drive which required a separate custom PC 5.25 Floppy Disk Controller Card , different for each Mac model. It is the only 5 + 1 ⁄ 4 -inch drive manufactured by Apple that can be used by the Macintosh. This drive was for use with industry standard double-sided 5 + 1 ⁄ 4 -inch 360-kilobyte formatted flexible disks. It was similar in appearance to the Disk IIc. Through

3210-551: The Type 1 Diskette in 1973, the industry continued to use the terms "floppy disk" or "floppy". In 1976, Shugart Associates introduced the 5¼-inch floppy disk drive. By 1978, there were more than ten manufacturers producing such drives. There were competing floppy disk formats , with hard- and soft-sector versions and encoding schemes such as differential Manchester encoding (DM), modified frequency modulation (MFM), M FM and group coded recording (GCR). The 5¼-inch format displaced

3317-618: The bias , or the DC coefficient . The disparity of a bit pattern is the difference in the number of one bits vs the number of zero bits. The running disparity is the running total of the disparity of all previously transmitted bits. The simplest possible line code, unipolar , gives too many errors on such systems, because it has an unbounded DC component. Most line codes eliminate the DC component – such codes are called DC-balanced , zero-DC, or DC-free. There are three ways of eliminating

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3424-453: The de facto standards for hard disks by the early 1990s. Line coding should make it possible for the receiver to synchronize itself to the phase of the received signal. If the clock recovery is not ideal, then the signal to be decoded will not be sampled at the optimal times. This will increase the probability of error in the received data. Biphase line codes require at least one transition per bit time. This makes it easier to synchronize

3531-485: The "UniDisk 5.25" to distinguish the similarly-named drives. Since the UniDisk could fully replace the Disk II in all its uses, the original Disk II was discontinued at this point. In 1986 a Platinum -gray version of the drive named the Apple 5.25 Drive (A9M0107) was introduced alongside the first Platinum-colored computer, the Apple IIGS . The drive's name was similar to that of the Apple 3.5 Drive , also released with

3638-458: The 140-kilobyte Disk II format. However, the external UniDisk 3.5 drive required a ROM upgrade (for existing Apple IIc machines; new ones shipped after this time had it from the factory) or a new kind of disk controller card (the so-called "Liron Card", for the Apple IIe) to be used. The much larger capacity and higher bitrate of the 3 + 1 ⁄ 2 -inch drives made it impractical to use

3745-398: The 1990s were non-networked, and floppy disks were the primary means to transfer data between computers, a method known informally as sneakernet . Unlike hard disks, floppy disks were handled and seen; even a novice user could identify a floppy disk. Because of these factors, a picture of a 3½-inch floppy disk became an interface metaphor for saving data. As of 2024 , the floppy disk symbol

3852-469: The 21st century, as a form of skeuomorphic design . 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 data storage capacity and data transfer speed , such as USB flash drives , memory cards , optical discs , and storage available through local computer networks and cloud storage . The first commercial floppy disks, developed in

3959-527: The 720 KB double density 3½-inch microfloppy disk on its Convertible laptop computer in 1986 and the 1.44 MB (1,474,560 bytes) high-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, Y-E Data introduced a drive for 2.88 MB Double-Sided Extended-Density (DSED) diskettes which was used by IBM in its top-of-the-line PS/2 and some RS/6000 models and in

4066-548: The 8-inch one for most uses, and the hard-sectored disk format disappeared. The most common capacity of the 5¼-inch format in DOS-based PCs was 360 KB (368,640 bytes) for the Double-Sided Double-Density (DSDD) format using MFM encoding. In 1984, IBM introduced with its PC/AT the 1.2 MB (1,228,800 bytes) dual-sided 5¼-inch floppy disk, but it never became very popular. IBM started using

4173-463: The Apple ///, many former Apple II users quickly devised a way to adapt their existing and cheaper Disk II drives; however, only one external Disk II was supported in this manner. The Disk III was the first to allow daisy chaining of up to three additional drives to the single 26-pin ribbon cable connector on the Apple ///, for a total of 4 floppy disk drives – the Apple /// was the first Apple to contain

4280-457: The Apple ///. That machine thus continued to use the same Shugart design as the Disk II. The first variation of the Disk II introduced for the Apple ///, called the Disk III (A3M0004), used the identical drive mechanism inside a modified plastic case with a proprietary connector. With some modification both drives are interchangeable. Though Apple sought to force the purchase of new drives with

4387-526: The Apple III Plus, it was the first to adopt Apple's standard DB-19 floppy drive connector. The Disk IIc (A2M4050) was a half-height 5 + 1 ⁄ 4 -inch floppy disk drive introduced by Apple Computer in 1984 styled for use alongside the Apple IIc personal computer, the only Apple II to contain a 5 + 1 ⁄ 4 -inch built-in disk drive mechanism. The disk port on the original IIc

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4494-663: The DC component: Bipolar line codes have two polarities, are generally implemented as RZ, and have a radix of three since there are three distinct output levels (negative, positive and zero). One of the principle advantages of this type of code is that it can eliminate any DC component. This is important if the signal must pass through a transformer or a long transmission line. Unfortunately, several long-distance communication channels have polarity ambiguity. Polarity-insensitive line codes compensate in these channels. There are three ways of providing unambiguous reception of 0 and 1 bits over such channels: For reliable clock recovery at

4601-406: The Disk II was adapted, was a single-sided, 35-track drive. However, it was common for users to manually flip the disk to utilize the opposite side, after cutting a second notch on the diskette's protective shell to allow write-access. Most commercial software using more than one disk side was shipped on such "flippy" disks as well. Only one side could be accessed at once, but it did essentially double

4708-534: The IIGS. Like the DuoDisk and Disk IIc before them, the UniDisk and Apple 5.25 Drive were half-height disk mechanisms inside an individual drive enclosure. Both drives featured a daisy chain pass-through port. While the drives were essentially interchangeable among Apple II computers, both with each other and with the earlier drives, minor electrical differences dictated that only the Apple 5.25 Drive could be used with

4815-565: The SA-390 drives didn't work without adjustments while others simply wouldn't work at all. Fellow engineer Cliff Huston came up with several procedures for resuscitating the faulty drives on the assembly line. When Apple sent an order into Shugart for more SA-390s, a Shugart engineer admitted that the disk drive manufacturer had been scamming Apple and that the SA-390s were actually rejected SA-400s that had failed to pass factory inspection. The idea

4922-551: The Shugart SA-400, which was the first commercially available 5 + 1 ⁄ 4 -inch diskette drive. Apple purchased only the bare drive mechanisms without the standard SA-400 controller board, replaced it with Wozniak's board design, and then stamped the Apple rainbow logo onto the faceplate. Early production at Apple was handled by two people, and they assembled 30 drives a day. By 1982, Apple switched to Alps drives for cost reasons. Normal storage capacity per disk side

5029-461: The Shugart controller's manual, Wozniak attempted to develop an FM -type controller with 10 sector per track storage, but realized that Group Coded Recording could fit 13 sectors per track. Wozniak called the resultant Disk II system "my most incredible experience at Apple and the finest job I did", and credited it and VisiCalc with the Apple II's success. Steve Wozniak found out that some of

5136-473: The Sony design, introduced in 1983 by many manufacturers, was then rapidly adopted. By 1988, the 3½-inch was outselling the 5¼-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, 5¼-inch disks had been superseded by 3½-inch disks. During this time, PCs frequently came equipped with drives of both sizes. By

5243-647: The United States' nuclear forces". The government planned to update some of the technology by the end of the 2017 fiscal year. Use in Japan's government ended in 2024. Windows 10 and Windows 11 no longer come with drivers for floppy disk drives (both internal and external). However, they will still support them with a separate device driver provided by Microsoft. The British Airways Boeing 747-400 fleet, up to its retirement in 2020, used 3½-inch floppy disks to load avionics software. Sony, who had been in

5350-416: The capacity of each floppy diskette, an important consideration especially in the early years when media was still quite expensive. In the Disk II, the full-height drive mechanism shipped inside a beige-painted metal case and connected to the controller card via a 20-pin ribbon cable ; the controller card was plugged into one of the bus slots on the Apple's mainboard. The connector is very easy to misalign on

5457-480: The card in any of the normal slots (i.e. all except slot 0 of the Apple II/II+ or the special memory expansion slots of the later models), Apple's printed manuals suggested using slot 6 for the first controller card; most Apple II software expects this slot to be used for the main 5 + 1 ⁄ 4 -inch disk drive and fails otherwise. A Bell & Howell version of the Disk II was also manufactured by Apple in

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5564-409: The computer in finding and synchronizing with the data in each track. The later 3½-inch drives of the mid-1980s did not use sector index holes, but instead also used synchronization patterns. Most 3½-inch drives used a constant speed drive motor and contain the same number of sectors across all tracks. This is sometimes referred to as Constant Angular Velocity (CAV). In order to fit more data onto

5671-421: The computer, and beneath the monitor. Each unit requires its own disk controller card (as each card can still control only two drives) and the number of units is thus limited to the number of available slots; in practice, few uses of the Apple II computer can make good use of more than two 5 + 1 ⁄ 4 -inch drives, so this limitation matters little. Originally released with a DB-25 connector to match that of

5778-449: The connector. They used different connectors that could not be misaligned in later drives. DB-19 adapters for the original Disk II were eventually available for use with Apple's later connector standard. Up to 14 drives could be attached to one Apple II or Apple IIe computer - two drives per controller card, one card per slot, and there were seven usable slots per computer. While the DOS and ProDOS operating systems worked equally well with

5885-502: The controller card, which will short out a certain IC in the drive; if later connected correctly, a drive damaged this way will delete data from any disk inserted into it as soon as it starts spinning, even write-protected disks such as those used to distribute commercial software. This problem resulted in numerous customer complaints and repairs, which led to Apple printing warning messages in their user's manuals to explain how to properly install

5992-406: The corresponding sensor; this was mainly a hardware cost-saving measure. The core of the 3½-inch disk is the same as the other two disks, but the front has only a label and a small opening for reading and writing data, protected by the shutter—a spring-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

6099-399: The current is reversed the magnetization aligns in the opposite direction, encoding one bit of data. To read data, the magnetization of the particles in the media induce a tiny voltage in the head coil as they pass under it. This small signal 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 it to

6206-835: 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 8 inches (203.2 mm). 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 to non-existent. Some individuals and organizations continue to use older equipment to read or transfer data from floppy disks. Floppy disks were so common in late 20th-century culture that many electronic and software programs continue to use save icons that look like floppy disks well into

6313-399: The disk media, an action originally accomplished by a disk-load solenoid. Later drives held the heads out of contact until a front-panel lever was rotated (5¼-inch) or disk insertion was complete (3½-inch). To write data, current is sent through a coil in the head as the media rotates. The head's magnetic field aligns the magnetization of the particles directly below the head on the media. When

6420-442: The disk shell are not quite square: its width is slightly less than its depth, so that it is impossible to insert the disk into a drive slot sideways (i.e. rotated 90 degrees from the correct shutter-first orientation). A diagonal notch at top right ensures that the disk is inserted into the drive in the correct orientation—not upside down or label-end first—and an arrow at top left indicates direction of insertion. The drive usually has

6527-466: The disk to keep them from accumulating on the heads. The cover is usually a one-part sheet, double-folded with flaps glued or spot-welded together. A small notch on the side of the disk identifies whether it is writable, as detected by a mechanical switch or photoelectric sensor . In the 8-inch disk, the notch being covered or not present enables writing, while in the 5¼-inch disk, the notch being present and uncovered enables writing. Tape may be used over

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6634-482: The drive itself nor the physical bit density was changed. This update had the disadvantage of not automatically booting older 13 sector Apple II software. Since the Disk II controller was completely software-operated, the user had total control over the encoding and format so long as it was within the physical limits of the drive mechanism and media. This also allowed software companies to use all sorts of ingenious copy protection schemes. The Shugart SA-400, from which

6741-538: The drives' automatic disk-eject feature, although they could be used with third-party controllers. There is one 5 + 1 ⁄ 4 -inch drive made by Apple that is completely incompatible with all the drives named above. In 1987, Apple sought to better compete in the IBM dominated business market by offering a means of cross-compatibility. Alongside the release of the Macintosh SE & Macintosh II , Apple released

6848-406: The eight ways one might try to insert the diskette, only one is correct, and only that one will fit. An excellent design. A spindle motor in the drive rotates the magnetic medium at a certain speed, while a stepper motor-operated mechanism 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

6955-692: The existing 3½-inch designs was the SuperDisk in the late 1990s, using very narrow data tracks and a high precision head guidance mechanism with a capacity of 120 MB and backward-compatibility with standard 3½-inch floppies; a format war briefly occurred between SuperDisk and other high-density floppy-disk products, although ultimately recordable CDs/DVDs, solid-state flash storage, and eventually cloud-based online storage would render 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. In

7062-555: The flexibility of floppy disks combined with greater capacity, but remained niche due to costs. High-capacity backward compatible floppy technologies became popular for a while and were sold as an option or even included in standard PCs, but in the long run, their use 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. As opposed to other solutions, no new drive type or special software

7169-457: The floppy disk business since 1983, ended domestic sales of all six 3½-inch floppy disk models as of March 2011. This has been viewed by some as the end of the floppy disk. While production of new floppy disk media has ceased, sales and uses of this media from inventories is expected to continue until at least 2026. For more than two decades, the floppy disk was the primary external writable storage device used. Most computing environments before

7276-512: The general population, floppy disks were often used to store a computer's operating system (OS). Most home computers from that time have an elementary OS and BASIC stored in read-only memory (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 like Windows or Adobe Photoshop required a dozen disks or more. In 1996, there were an estimated five billion standard floppy disks in use. An attempt to enhance

7383-431: The greater capacity, compatibility with existing CD-ROM drives, and—with the advent of re-writeable CDs and packet writing—a similar reusability as floppy disks. However, CD-R/RWs remained mostly an archival medium, not a medium for exchanging data or editing files on the medium itself, because there was no common standard for packet writing which allowed for small updates. Other formats, such as magneto-optical discs , had

7490-407: 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 zero synchronization was attempted. All 8-inch and some 5¼-inch drives used a mechanical method to locate sectors, known as either hard sectors or soft sectors , and is the purpose of

7597-450: The host computer system. 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 broken up 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

7704-499: The late 1960s, were 8 inches (203.2 mm) in diameter; they became commercially available in 1971 as a component of IBM products and both drives and disks were then sold separately starting 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

7811-470: The later (ROM 3) version of the Apple IIGS and with the Apple IIe Card on a Macintosh LC . In 1984, Apple had opted for the more modern, Sony-designed 3 + 1 ⁄ 2 -inch floppy disk in late-model Lisas and the new Apple Macintosh . Accordingly, they attempted to introduce a new 3 + 1 ⁄ 2 -inch 800-kilobyte floppy disk format for the Apple II series as well, to eventually replace

7918-424: 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

8025-429: The media to reliably store the maximal amount of data in a given space. Early disk drives used very simple encoding schemes, such as RLL (0,1) FM code, followed by RLL (1,3) MFM code which were widely used in hard disk drives until the mid-1980s and are still used in digital optical discs such as CD , DVD , MD , Hi-MD and Blu-ray using EFM and EFMPLus codes. Higher density RLL (2,7) and RLL (1,7) codes became

8132-399: 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 3½-inch drives automatically engage the spindle and heads when a disk is inserted, doing the opposite with

8239-400: The medium, and sector position is determined by the disk controller or low-level software from patterns marking the start of a sector. Generally, the same 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 as Apple DOS , do not use the index hole, and the drives designed for such systems often lack

8346-493: 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 higher capacity, its smaller physical size, and its rigid case which provided better protection from dirt and other environmental risks. 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

8453-485: The mid-1990s, mechanically incompatible higher-density floppy disks were introduced, like the Iomega Zip disk . Adoption was limited by the competition between proprietary formats and the need to buy expensive drives for computers where the disks would be used. In some cases, failure in market penetration was exacerbated by the release of higher-capacity versions of the drive and media being not backward-compatible with

8560-526: The notch to change the mode of the disk. Punch devices were sold to convert read-only 5¼" disks to writable ones, and also to enable writing on the unused side of single-sided disks for computers with single-sided drives. The latter worked because single- and double-sided disks typically contained essentially identical actual magnetic media, for manufacturing efficiency. Disks whose obverse and reverse sides were thus used separately in single-sided drives were known as flippy disks . Disk notching 5¼" floppies for PCs

8667-485: 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 5¼-inch format made it difficult for these diverse mutually-incompatible new formats to gain significant market share. A variant on

8774-465: The original 1979 Disk II controller and newer 1983 Uni/Duo Disk I/O controller (655-0101). The circuitry of these two controllers are identical. The Disk II header pin numbering is per the Disk II controller card silkscreen and the circuit schematic given in the DOS 3.3 manual. The Uni/Duo Disk D-19 pinout is taken from the Apple //c Reference Manual, Volume 1 . NOTES: Floppy disk A floppy disk or floppy diskette (casually referred to as

8881-492: 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 but no floppy drive; this made USB-connected floppy drives popular accessories, as the iMac came without any writable removable media device. Recordable CDs were touted as an alternative, because of

8988-409: The press of the eject button. On Apple Macintosh computers with built-in 3½-inch disk drives, the ejection button is replaced by software controlling an ejection motor which only does so when the operating system no longer needs to access the drive. The user could drag the image of the floppy drive to the trash can on the desktop to eject the disk. In the case of a power failure or drive malfunction,

9095-399: The rate of the code, while the remaining two specify the minimal d and maximal k number of zeroes between consecutive ones. This is used in both telecommunications and storage systems that move a medium past a fixed recording head . Specifically, RLL bounds the length of stretches (runs) of repeated bits during which the signal does not change. If the runs are too long, clock recovery

9202-403: The read operation; other errors are permanent and the disk controller will signal a failure to the operating system if multiple attempts to read the data still fail. After a disk is inserted, a catch or lever at the front of the drive is manually lowered to prevent the disk from accidentally emerging, engage the spindle clamping hub, and in two-sided drives, engage the second read/write head with

9309-456: The receiver, a run-length limitation may be imposed on the generated channel sequence, i.e., the maximum number of consecutive ones or zeros is bounded to a reasonable number. A clock period is recovered by observing transitions in the received sequence, so that a maximum run length guarantees sufficient transitions to assure clock recovery quality. RLL codes are defined by four main parameters: m , n , d , k . The first two, m / n , refer to

9416-591: The reliability problems of the Apple-built "Twiggy" drive mechanisms, the products never shipped. In 1984, shortly after the introduction of the Apple IIe the previous year, Apple offered a combination of two, two third-height , 140-kilobyte Disk II drive mechanisms side-by-side in a single plastic case, called the DuoDisk (A9M0108), which can not be daisy-chained. The unit was designed to be stacked on top of

9523-453: The same as the full-height Disk II, Apple sold the Disk IIc for US$ 329, and other companies later sold similar drives for less. Just over a year after the release of the DuoDisk, Apple introduced the UniDisk (A9M0104) in a plastic case whose styling was similar to that of the DuoDisk. After the release of the UniDisk 3.5 a few months later, the UniDisk was often informally referred to as

9630-585: The same low-level disk format, and are all interchangeable with the use of simple adapters, consisting of no more than two plugs and wires between them. Most DuoDisk drives, the Disk IIc, the UniDisk 5.25" and the AppleDisk 5.25" even use the same 19-pin D-Sub connector, so they are directly interchangeable. The only 5 + 1 ⁄ 4 " drive Apple sold aside from the Disk II family was a 360k MFM unit made to allow Mac IIs and SEs to read PC floppy disks. This

9737-651: The second-generation NeXTcube and NeXTstation ; however, this format had limited market success due to lack of standards and movement to 1.44 MB drives. Throughout the early 1980s, limits of the 5¼-inch format became clear. Originally designed to be more practical than the 8-inch format, it was becoming considered too large; as the quality of recording media grew, data could be stored in a smaller area. Several solutions were developed, with drives at 2-, 2½-, 3-, 3¼-, 3½- and 4-inches (and Sony 's 90 mm × 94 mm (3.54 in × 3.70 in) disk) offered by various companies. They all had several advantages over

9844-502: 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 data has a header that identifies the sector location on the disk. A cyclic redundancy check (CRC) is written into the sector headers and at the end 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

9951-413: The small hole in the jacket, off to the side of the spindle hole. A light beam sensor detects when a punched hole in the disk is visible through the hole in the jacket. For a soft-sectored disk, there is only a single hole, which is used to locate the first sector of each track. Clock timing is then used to find the other sectors behind it, which requires precise speed regulation of the drive motor. For

10058-474: The software-driven Disk II controller because the 1-megahertz 6502 CPU in the Apple II line was too slow to be able to read them. Thus, a new and much more advanced (and correspondingly expensive) hardware floppy controller had to be used. And many original Apple IIs could not use the new controller card at all without further upgrades. Also, almost all commercial software for the Apple II series continued to be published on 5 + 1 ⁄ 4 -inch disks which had

10165-408: The spindle of the drive. Typical 3½-inch disk magnetic coating materials are: Two holes at the bottom left and right indicate whether the disk is write-protected and whether it is high-density; these holes are spaced as far apart as the holes in punched A4 paper, allowing write-protected high-density floppy disks to be clipped into international standard ( ISO 838 ) ring binders . The dimensions of

10272-400: The track length increases. While the original IBM 8-inch disk was actually so defined, the other sizes are defined in the metric system, their usual names being but rough approximations. Digital frequency modulation Common line encodings are unipolar , polar , bipolar , and Manchester code . After line coding, the signal is put through a physical communication channel, either

10379-514: The use of a special Macintosh Apple File Exchange utility shipped with it, the drive could read files from, and write files to, floppy disks in MS-DOS formats. Software "translators" could convert documents between WordStar and MacWrite formats, among others. The drive is incompatible with all Apple II computers and the Apple IIe Card for the Macintosh LC as well; it also does not allow

10486-442: The user not to expose it to dangerous conditions. Rough treatment or removing the disk from the drive while the magnetic media is still spinning is likely to cause damage to the disk, drive head, or stored data. On the other hand, the 3½‑inch floppy disk has been lauded for its mechanical usability by human–computer interaction expert Donald Norman : A simple example of a good design is the 3½-inch magnetic diskette for computers,

10593-416: Was 113.75  KiB with Apple DOS 3.2.1 and earlier (256 bytes per sector, 13 sectors per track, 35 tracks per side), or 140 KiB with DOS 3.3 and ProDOS (256 bytes per sector, 16 sectors per track, 35 tracks per side). The 16-sector hardware upgrade introduced in 1980 for use with DOS 3.3 modified only the controller card firmware to use a more efficient GCR code called " 6 and 2 encoding ". Neither

10700-515: Was designed specifically for use with the 1977 Apple II personal computer to replace the slower cassette tape storage. Apple produced at least six variants of the basic 5 + 1 ⁄ 4 -inch Disk II concept over the course of the Apple II series' lifetime: The Disk II, the Disk III, the DuoDisk, the Disk IIc, the UniDisk 5.25" and the Apple 5.25 Drive. While all of these drives look different, and use four different connector types, they're all electronically extremely similar. They can all use

10807-409: Was generally only required where users wanted to overwrite original 5¼" disks of store-bought software, which somewhat commonly shipped with no notch present. Another LED/photo-transistor pair located near the center of the disk detects the index hole once per rotation in the magnetic disk. Detection occurs whenever the drive's sensor, the holes in the correctly inserted floppy's plastic envelope and

10914-468: Was little financial incentive to omit the device from a system. Subsequently, enabled by the widespread support for USB flash drives and BIOS boot, manufacturers and retailers progressively reduced the availability of floppy disk drives as standard equipment. In February 2003, Dell , one of the leading personal computer vendors, announced that floppy drives would no longer be pre-installed on Dell Dimension home computers, although they were still available as

11021-545: Was only designed to control one additional, external 5 + 1 ⁄ 4 -inch disk drive, and as such, this particular drive omitted a daisy-chain port in back. It was possible to use it on other Apple II models, so long as it came last in the chain of drive devices (due to lacking a daisy-chain port); but since the Disk IIc was sold without a controller card, the Apple IIc computer needing none, it had to be adapted to an existing Disk II controller card in this case. Essentially

11128-443: Was required that impeded adoption, since all that was necessary was an already common USB port . By 2002, most manufacturers still provided floppy disk drives as standard equipment to meet user demand for file-transfer and an emergency boot device, as well as for the general secure feeling of having the familiar device. By this time, the retail cost of a floppy drive had fallen to around $ 20 (equivalent to $ 34 in 2023), so there

11235-413: Was that Apple couldn't get the drives to work and would be forced to go back and purchase more expensive SA-400s. The Disk II was very successful for Apple, being the cheapest floppy disk system ever sold up to that point and immensely profitable for the company, in addition to having nearly 20% more storage space than standard FM drives. For a while, the only direct competitor in the microcomputer industry

11342-538: Was the TRS-80 Model I , which had used only standard FM storage for 85k. The Atari 8-bit computer 's disk drives' throughputs were much slower than the Disk II's 15 KB/s, seriously affecting their ability to compete in the business market. However, the advantage of Wozniak's design was somewhat nullified when the cost of double-density MFM controllers dropped only a year after the Disk II's introduction. The initial Disk II drives (A2M0003) were modifications of

11449-487: Was the difference between hobbyist devices and a computer. You couldn't have expected, say, VisiCalc, to run on a cassette system." Recognizing that the II needed a disk drive to be taken seriously, Apple set out to develop a disk drive and a DOS to run it. Wozniak spent the 1977 Christmas holidays adapting his controller design, which reduced the number of chips used by a factor of 10 compared to existing controllers. Still lacking

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