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112-460: The Transaction-Safe FAT File System (TFAT) of the TFAT12 , TFAT16 and TFAT32 file systems is a driver layer modification to the original FAT file systems FAT12 , FAT16 and FAT32 maintaining two copies (FAT 0 and FAT 1) of the file allocation table instead of two identical ones. While performing a drive operation, changes would be made to FAT 1. When the operation is complete,

224-561: A BPB with 32-bit entry for the number of sectors, as introduced since DOS 3.31 (see FAT16B below), keeping the cluster size and reducing the logical sector size in the BPB down to 512 bytes, while at the same time increasing the counts of logical sectors per cluster, reserved logical sectors, total logical sectors, and logical sectors per FAT by the same factor. A parallel development in MS-DOS / PC DOS which allowed an increase in

336-439: 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

448-443: 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

560-527: A confusing compatibility situation. Prior to 1995, versions of DOS accessed the disk via CHS addressing only. When Windows 95 (MS-DOS 7.0) introduced LBA disk access, partitions could start being physically located outside the first c. 8 GB of this disk and thereby out of the reach of the traditional CHS addressing scheme. Partitions partially or fully located beyond the CHS barrier therefore had to be hidden from non-LBA-enabled operating systems by using

672-472: A contiguous area of disk storage. Each entry contains either the number of the next cluster in the file, or else a marker indicating the end of the file, unused disk space, or special reserved areas of the disk. The root directory of the disk contains the number of the first cluster of each file in that directory. The operating system can then traverse the FAT, looking up the cluster number of each successive part of

784-650: 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

896-428: 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

1008-474: 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

1120-851: A few hundred bytes in size. As MS-DOS 3.0 formatted all 16 MB-32 MB partitions in the FAT16 format, a 20 MB hard disk formatted under MS-DOS 3.0 was not accessible by MS-DOS 2.0. MS-DOS 3.0 to MS-DOS 3.30 could still access FAT12 partitions under 15 MB, but required all 16 MB-32 MB partitions to be FAT16, and so could not access MS-DOS 2.0 partitions in this size range. MS-DOS 3.31 and higher could access 16 MB-32 MB FAT12 partitions again. MS-DOS and PC DOS implementations of FAT12 and FAT16 could not access disk partitions larger than 32 megabytes. Several manufacturers developed their own FAT variants within their OEM versions of MS-DOS. Some vendors ( AST and NEC ) supported eight , instead of

1232-410: A few values reserved to indicate unallocated space or the end of a list) and the size of the disk cluster. Even if only one byte of storage is needed to extend a file, an entire cluster must be allocated to it. As a result, large numbers of small files can result in clusters being allocated that may contain mostly "empty" data to meet the minimum cluster size. Originally designed as an 8-bit file system,

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1344-406: A formatted capacity of 160 KB (FAT ID 0xFE ) for single-sided 5.25-inch floppy drives, and PC DOS 1.1 added support for a double-sided format with 320 KB (FAT ID 0xFF ). PC DOS 2.0 introduced support for 9-sector floppy formats with 180 KB (FAT ID 0xFC ) and 360 KB (FAT ID 0xFD ). 86-DOS 1.00 and PC DOS 1.0 directory entries included only one date,

1456-413: 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

1568-544: A hidden file called " EA␠DATA.␠SF " in the root directory of the FAT12 or FAT16 volume. This file is indexed by two previously reserved bytes in the file's (or directory's) directory entry at offset 0x14 . In the FAT32 format, these bytes hold the upper 16 bits of the starting cluster number of the file or directory, hence making it impossible to store OS/2 EAs on FAT32 using this method. However,

1680-420: 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

1792-510: A logical file system with 8.3 filenames and makes the use of either FAT12, FAT16, FAT32 or exFAT mandatory for its physical layer for compatibility. The file system uses an index table stored on the device to identify chains of data storage areas associated with a file, the File Allocation Table ( FAT ). The FAT is statically allocated at the time of formatting. The table is a linked list of entries for each cluster ,

1904-515: A power outage could lead to data loss. In addition, directories created under the desktop OS may not be transaction-safe even if the drive is later attached to a TFAT/TexFAT aware operating system. File Allocation Table File Allocation Table ( FAT ) is a file system developed for personal computers and was the default filesystem for the MS-DOS and Windows 9x operating systems. Originally developed in 1977 for use on floppy disks , it

2016-499: A pre-installed tool to convert a FAT file system into NTFS directly without the need to rewrite all files, though this cannot be reversed easily. The FAT file system is used in removable media such as floppy disks , super-floppies , memory and flash memory cards or USB flash drives . FAT is supported by portable devices such as PDAs , digital cameras , camcorders , media players , and mobile phones. The DCF file system adopted by almost all digital cameras since 1998 defines

2128-557: 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

2240-468: 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

2352-449: A series of discussions between McDonald and Bill Gates . It was introduced with 8-bit table elements (and valid data cluster numbers up to 0xBF ) in a precursor to Microsoft 's Standalone Disk BASIC-80 for an 8080 -based successor of the NCR 7200 model VI data-entry terminal, equipped with 8-inch (200 mm) floppy disks, in 1977 or 1978. In 1978, Standalone Disk BASIC-80

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2464-505: 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

2576-447: 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

2688-411: 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

2800-594: A special mark byte indicating the presence of extended attributes to help speed up things. (This extension is critically incompatible with the FAT32+ method to store files larger than 4 GB minus 1 on FAT32 volumes.) Extended attributes are accessible via the Workplace Shell desktop, through REXX scripts, and many system GUI and command-line utilities (such as 4OS2 ). Floppy disk A floppy disk or floppy diskette (casually referred to as

2912-439: Is 4  GB minus 1 byte, or 4,294,967,295 (2  − 1) bytes. This limit is a consequence of the 4-byte file length entry in the directory table and would also affect relatively huge FAT16 partitions enabled by a sufficient sector size. Like FAT12 and FAT16, FAT32 does not include direct built-in support for long filenames, but FAT32 volumes can optionally hold VFAT long filenames in addition to short filenames in exactly

3024-475: 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

3136-561: Is also named FAT32X in order to indicate usage of LBA disk access instead of CHS. On such partitions, CHS-related geometry entries, namely the CHS sector addresses in the MBR as well as the number of sectors per track and the number of heads in the EBPB record, may contain no or misleading values and should not be used. OS/2 heavily depends on extended attributes (EAs) and stores them in

3248-456: 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

3360-421: Is determined when the volume is formatted, and is stored in a 16-bit field. For a given number RDE and sector size SS , the number RDS of root directory sectors is RDS = ceil((RDE × 32) / SS) , and RDE is normally chosen to fill these sectors, i.e., RDE × 32 = RDS × SS . FAT12 and FAT16 media typically use 512 root directory entries on non-floppy media. Some third-party tools, like mkdosfs, allow

3472-448: Is known as FAT16B . Since older versions of DOS were not designed to cope with more than 65,535 sectors, it was necessary to introduce a new partition type for this format in order to hide it from pre-3.31 issues of DOS. The original form of FAT16 (with less than 65,536 sectors) had a partition type 0x04 . To deal with disks larger than this, type 0x06 was introduced to indicate 65,536 or more sectors. In addition to this,

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3584-509: Is proportionally larger. Much later, Windows NT increased the maximum cluster size to 64 KB, by considering the sectors-per-cluster count as unsigned. However, the resulting format was not compatible with any other FAT implementation of the time, and it generated greater internal fragmentation . Windows 98 , SE and ME also supported reading and writing this variant, but its disk utilities did not work with it and some FCB services are not available for such volumes. This contributes to

3696-428: 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

3808-549: Is used on floppy disks, FAT16 and FAT32 are typically found on the larger media. FAT is used internally for the EFI system partition in the boot stage of EFI -compliant computers. Hidden FAT filesystems are also used in the UEFI boot partition on modern PCs. FAT is still used in drives expected to be used by multiple operating systems, such as in shared Windows, Linux and DOS environments. Microsoft Windows additionally comes with

3920-551: 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

4032-465: The command prompt , PowerShell or third-party tools, or by formatting the volume on a non-Windows system or on a Windows 9x system with FAT32 support and then transferring it to the Windows NT system. In August 2024, Microsoft released an update to Windows 11 preview builds that allows for the creation of FAT32 partitions up to 2TB in size. The maximal possible size for a file on a FAT32 volume

4144-509: The physical sector size (still 512 bytes) on the disk. The DOS-BIOS or System BIOS would then combine multiple physical sectors into logical sectors for the file system to work with. These changes were transparent to the file system implementation in the DOS kernel. The underlying DOS-BIOS translated these logical sectors into physical sectors according to partitioning information and the drive's physical geometry. The drawback of this approach

4256-529: The 16-bit disk sector count to 32 bits in the BPB. Although the on-disk changes were minor, the entire DOS disk driver had to be converted to use 32-bit sector numbers, a task complicated by the fact that it was written in 16-bit assembly language . The result was initially called the DOS 3.31 Large File System . Microsoft 's DSKPROBE tool refers to type 0x06 as BigFAT , whereas some older versions of FDISK described it as BIGDOS . Technically, it

4368-398: 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

4480-469: 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

4592-527: 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

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4704-548: 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

4816-508: The FAT ;1 table would be copied to FAT 0, updating the stable view of the file system. The Transaction-Safe Extended FAT File System (TexFAT), TexFAT provides similar functionality to TFAT using the exFAT file system as the base file system instead of FAT. Introduced with Windows Embedded CE 6.0 , it is sometimes referred to as TFAT as well, which can lead to confusion with the original TFAT described above. The use of exFAT as

4928-516: The FATs. FAT12 remains in use on all common floppy disks , including 1.44 MB and later 2.88 MB disks (media descriptor byte 0xF0 ). In 1984, IBM released the PC AT , which required PC DOS 3.0 to access its 20 MB hard disk. Microsoft introduced MS-DOS 3.0 in parallel. Cluster addresses were increased to 16-bit, allowing for up to 65,526 clusters per volume. However,

5040-473: 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

5152-647: 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

5264-547: The Windows NT line, native support for FAT32 arrived in Windows 2000 . A free FAT32 driver for Windows NT 4.0 was available from Winternals , a company later acquired by Microsoft. The acquisition of the driver from official sources is no longer possible. Since 1998, Caldera's dynamically loadable DRFAT32 driver could be used to enable FAT32 support in DR-DOS. The first version of DR-DOS to natively support FAT32 and LBA access

5376-498: The cluster number. The FAT32 boot sector uses a 32-bit field for the sector count, limiting the maximal FAT32 volume size to 2  terabytes with a sector size of 512  bytes . The maximum FAT32 volume size is 16 TB with a sector size of 4,096 bytes. The built-in Windows shell disk format tool on Windows NT arbitrarily only supports volume sizes up to 32 GB, but Windows supports reading and writing to preexisting larger FAT32 volumes, and these can be created with

5488-409: 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

5600-406: 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

5712-399: 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

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5824-515: The disk driver was expanded to cope with more than 65,535 sectors as well. The only other difference between the original FAT16 and the newer FAT16B format is the usage of a newer BPB format with 32-bit sector entry. Therefore, newer operating systems supporting the FAT16B format can cope also with the original FAT16 format without any necessary changes. If partitions to be used by pre-DOS 3.31 issues of DOS need to be created by modern tools,

5936-403: The disk file as a cluster chain until the end of the file is reached. Sub-directories are implemented as special files containing the directory entries of their respective files. Each entry in the FAT linked list is a fixed number of bits: 12, 16 or 32. The maximum size of a file or a disk drive that can be accessed is the product of the largest number that can be stored in the entries (less

6048-835: 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

6160-399: 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

6272-442: 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

6384-466: 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

6496-406: 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

6608-692: 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

6720-415: The file data area. Clusters containing bad sectors were marked unusable with the reserved value 0xFF7 in the FAT. While 86-DOS supported three disk formats (250.25 KB, 616 KB and 1232 KB, with FAT IDs 0xFF and 0xFE ) on 8-inch (200 mm) floppy drives, IBM PC DOS 1.0 , released with the original IBM Personal Computer in 1981, supported only an 8-sector floppy format with

6832-555: 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

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6944-457: 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

7056-512: 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

7168-431: 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

7280-407: 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

7392-450: 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

7504-524: The last modified date. PC DOS 1.1 added the last modified time. PC DOS 1.x file attributes included a hidden bit and system bit, with the remaining six bits undefined. At this time, DOS did not support sub-directories, but typically there were only a few dozen files on a diskette . The PC XT was the first PC with an IBM-supplied hard drive, and PC DOS 2.0 supported that hard drive with FAT12 ( FAT ID 0xF8 ). The fixed assumption of 8 sectors per clusters on hard disks practically limited

7616-499: 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

7728-424: 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

7840-399: The maximum number of clusters must increase as disk drive capacity increases, and so the number of bits used to identify each cluster has grown. The successive major variants of the FAT format are named after the number of table element bits: 12 ( FAT12 ), 16 ( FAT16 ), and 32 ( FAT32 ). There are several variants of the FAT file system (e.g. FAT12 , FAT16 and FAT32 ). FAT16 refers to both

7952-489: The maximum partition size to 16 MB for 512 byte sectors and 4 KB clusters. The BIOS Parameter Block ( BPB ) was introduced with PC DOS 2.0 as well, and this version also added read-only, archive , volume label , and directory attribute bits for hierarchical sub-directories. MS-DOS 3.0 introduced support for high-density 1.2 MB 5.25-inch diskettes (media descriptor 0xF9 ), which notably had 15 sectors per track, hence more space for

8064-483: The maximum possible FAT size was the introduction of multiple FAT partitions on a hard disk. To allow the use of more FAT partitions in a compatible way, a new partition type was introduced in PC ;DOS 3.2 (1986), the extended partition (EBR), which is a container for an additional partition called logical drive . Since PC DOS 3.3 (April 1987), there is another, optional extended partition containing

8176-484: The maximum possible number of sectors and the maximum partition size of 32 MB did not change. Although cluster addresses were 16 bits, this format was not what today is commonly understood as FAT16 . A partition type 0x04 indicates this form of FAT16 with less than 65,536 sectors (less than 32 MB for sector size 512). The benefit of FAT16 was the use of smaller clusters, making disk usage more efficient, particularly for large numbers of files only

8288-399: 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

8400-400: 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

8512-493: 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

8624-485: 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

8736-457: The new partition type 0x0E in the partition table instead. FAT16 partitions using this partition type are also named FAT16X . The only difference, compared to previous FAT16 partitions, is the fact that some CHS-related geometry entries in the BPB record, namely the number of sectors per track and the number of heads, may contain no or misleading values and should not be used. The number of root directory entries available for FAT12 and FAT16

8848-404: The next logical drive , and so on. The MBR of a hard disk can either define up to four primary partitions, or an extended partition in addition to up to three primary partitions. In November 1987, Compaq Personal Computer DOS 3.31 (a modified OEM version of MS-DOS 3.3 released by Compaq with their machines) introduced what today is simply known as the FAT16 format, with the expansion of

8960-526: 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

9072-485: 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

9184-621: The only criteria theoretically necessary to meet are a sector count of less than 65536, and the usage of the old partition ID ( 0x04 ). In practice however, type 0x01 and 0x04 primary partitions should not be physically located outside the first 32 MB of the disk, due to other restrictions in MS-DOS ;2.x, which could not cope with them otherwise. In 1988, the FAT16B improvement became more generally available through DR DOS  3.31, PC DOS 4.0, OS/2  1.1, and MS-DOS 4.0. The limit on partition size

9296-492: 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

9408-498: The original group of FAT file systems with 16-bit wide cluster entries and also to later variants. " VFAT " is an optional extension for long file names, which can work on top of any FAT file system. Volumes using VFAT long-filenames can be read also by operating systems not supporting the VFAT extension. The original FAT file system (or FAT structure , as it was called initially) was designed and implemented by Marc McDonald , based on

9520-409: 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,

9632-403: 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

9744-419: The same way as VFAT long filenames have been optionally implemented for FAT12 and FAT16 volumes. FAT32 was introduced with Windows 95 OSR2(MS-DOS 7.1) in 1996, although reformatting was needed to use it, and DriveSpace 3 (the version that came with Windows 95 OSR2 and Windows 98) never supported it. Windows 98 introduced a utility to convert existing hard disks from FAT16 to FAT32 without loss of data. In

9856-651: 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

9968-502: 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

10080-619: The size of directory entries was 16 bytes in Standalone Disk BASIC , MIDAS instead occupied 32 bytes per entry. Tim Paterson of Seattle Computer Products (SCP) was first introduced to Microsoft's FAT structure when he helped Bob O'Rear adapting the Standalone Disk BASIC-86 emulator port onto SCP's S-100 bus 8086 CPU board prototype during a guest week at Microsoft in May 1979. The final product

10192-413: 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

10304-658: The specifications of the file system itself. Therefore, even if default issues of MS-DOS and PC DOS were not able to cope with them, most of these vendor-specific FAT12 and FAT16 variants can be mounted by more flexible file system implementations in operating systems such as DR-DOS, simply by changing the partition ID to one of the recognized types. Also, if they no longer need to be recognized by their original operating systems, existing partitions can be "converted" into FAT12 and FAT16 volumes more compliant with versions of MS-DOS/PC DOS 4.0–6.3, which do not support sector sizes different from 512 bytes, by switching to

10416-408: 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

10528-405: The standard four , primary partition entries in their custom extended Master Boot Record ( MBR ), and they adapted MS-DOS to use more than a single primary partition. Other vendors worked around the volume size limits imposed by the 16-bit sector entries by increasing the apparent size of the sectors the file system operated on. These logical sectors were larger (up to 8192 bytes) than

10640-605: The table elements to 12 bits , reduced the number of FATs to two, redefined the semantics of some of the reserved cluster values, and modified the disk layout, so that the root directory was now located between the FAT and the data area for his implementation of FAT12 . Paterson also increased the nine-character (6.3) filename length limit to eleven characters to support CP/M -style 8.3 filenames and File Control Blocks . The format used in Microsoft Standalone Disk BASIC's 8-bit file system precursor

10752-415: The third-party FAT32 installable file system (IFS) driver FAT32.IFS version 0.70 and higher by Henk Kelder & Netlabs for OS/2, eComStation and ArcaOS stores extended attributes in extra files with filenames having the string " ␠EA.␠SF " appended to the regular filename of the file to which they belong. The driver also utilizes the byte at offset 0x0C in directory entries to store

10864-480: The underlying file system allows for larger files and larger partitions. TexFAT requires a hardware-specific driver designed for the type of media on which the TexFAT volume resides. Due to the lack of support in desktop operating systems , neither TFAT nor TexFAT are recommended for removable media. While the desktop OS could still read the drive, it could not use the transaction-safe features, so unexpected removal or

10976-442: 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,

11088-504: The user to set this parameter. In order to overcome the volume size limit of FAT16, while at the same time allowing DOS real-mode code to handle the format, Microsoft designed a new version of the file system, FAT32 , which supported an increased number of possible clusters, but could reuse most of the existing code, so that the conventional memory footprint was increased by less than 5 KB under DOS. Cluster values are represented by 32-bit numbers, of which 28 bits are used to hold

11200-449: Was OEM DR-DOS 7.04 in 1999. That same year IMS introduced native FAT32 support with REAL/32 7.90, and IBM 4690 OS added FAT32 support with version 2. Ahead Software provided another dynamically loadable FAT32.EXE driver for DR-DOS 7.03 with Nero Burning ROM in 2004. IBM introduced native FAT32 support with OEM PC DOS 7.1 in 1999. Two partition types have been reserved for FAT32 partitions, 0x0B and 0x0C . The latter type

11312-549: Was adapted for use on hard disks and other devices. The increase in disk drive capacity over time drove modifications to the design that resulted in versions: FAT12 , FAT16 , FAT32 , and exFAT . FAT was replaced with NTFS as the default file system on Microsoft operating systems starting with Windows XP . Nevertheless, FAT continues to be commonly used on relatively small capacity solid-state storage technologies such as SD card , MultiMediaCard (MMC) and eMMC because of its compatibility and ease of implementation. FAT

11424-436: Was dictated by the 8-bit signed count of sectors per cluster, which originally had a maximum power-of-two value of 64. With the standard hard disk sector size of 512 bytes, this gives a maximum of 32 KB cluster size, thereby fixing the "definitive" limit for the FAT16 partition size at 2 GB for sector size 512. On magneto-optical media, which can have 1 or 2 KB sectors instead of 0.5 KB, this size limit

11536-416: Was dropped with MS-DOS 1.20 . FAT12 used 12-bit entries for the cluster addresses; some values were reserved to mark the end of a chain of clusters, to mark unusable areas of the disk, or for other purposes, so the maximum number of clusters was limited to 4078. To conserve disk space, two 12-bit FAT entries used three consecutive 8-bit bytes on disk, requiring manipulation to unpack the 12-bit values. This

11648-409: 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

11760-918: Was increased memory used for sector buffering and deblocking. Since older DOS versions could not use large logical sectors, the OEMs introduced new partition IDs for their FAT variants in order to hide them from off-the-shelf issues of MS-DOS and PC DOS. Known partition IDs for logical sectored FATs include: 0x08 ( Commodore MS-DOS 3.x), 0x11 ( Leading Edge MS-DOS 3.x), 0x14 (AST MS-DOS 3.x), 0x24 (NEC MS-DOS 3.30 ), 0x56 ( AT&T MS-DOS 3.x), 0xE5 ( Tandy MS-DOS), 0xF2 ( Sperry IT MS-DOS 3.x, Unisys MS-DOS 3.3 – also used by Digital Research DOS Plus 2.1). OEM versions like Toshiba MS-DOS, Wyse MS-DOS 3.2 and 3.3, as well as Zenith MS-DOS are also known to have utilized logical sectoring. While non-standard and sub-optimal, these FAT variants are perfectly valid according to

11872-468: 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

11984-524: Was not supported by QDOS. By August 1980, QDOS had been renamed 86-DOS . Starting with 86-DOS 0.42 , the size and layout of directory entries was changed from 16 bytes to 32 bytes in order to add a file date stamp and increase the theoretical file size limit beyond the previous limit of 16 MB. 86-DOS 1.00 became available in early 1981. Later in 1981, 86-DOS evolved into Microsoft's MS-DOS and IBM PC DOS . The capability to read previously formatted volumes with 16-byte directory entries

12096-510: Was ported to the 8086 using an emulator on a DEC PDP-10 , since no real 8086 systems were available at this time. The FAT file system was also used in Microsoft's MDOS/MIDAS , an operating system for 8080/Z80 platforms written by McDonald since 1979. The Standalone Disk BASIC version supported three FATs, whereas this was a parameter for MIDAS. Reportedly, MIDAS was also prepared to support 10-bit, 12-bit and 16-bit FAT variants. While

12208-443: 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

12320-602: Was shown at Lifeboat Associates ' booth stand at the National Computer Conference in New York on June 4–7, 1979, where Paterson learned about the more sophisticated FAT implementation in MDOS/MIDAS and McDonald talked to him about the design of the file system. Between April and August 1980, while borrowing the FAT concept for SCP's own 8086 operating system QDOS 0.10 , Tim Paterson extended

12432-496: Was sufficient for the original floppy disk drives, and small hard disks up to 32 megabytes. The FAT16B version available with DOS 3.31 supported 32-bit sector numbers, and so increased the volume size limit. All the control structures fit inside the first track, to avoid head movement during read and write operations. Any bad sector in the control structures area would make the disk unusable. The DOS formatting tool rejected such disks completely. Bad sectors were allowed only in

12544-653: Was used on hard disks throughout the DOS and Windows 9x eras. Microsoft introduced NTFS with the Windows NT platform in 1993, but FAT remained the standard for the home user until the introduction of Windows XP in 2001. Windows Me was the final version of Windows to use FAT as its default file system. For floppy disks, FAT has been standardized as ECMA -107 and ISO / IEC  9293:1994 (superseding ISO 9293:1987 ). These standards cover FAT12 and FAT16 with only short 8.3 filename support; long filenames with VFAT were partially patented . While FAT12

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