The flexible magnetic disk, or diskette revolutionized computer disk storage in the 1970s. Diskettes, which were often called floppy disks or floppies, became ubiquitous in the 1980s and 1990s in their use with personal computers and home computers to distribute software, transfer data, and create backups.
Before hard disks became affordable, floppy disks were often also used to store a computer's operating system (OS), in addition to application software and data. Most home computers had a primary OS (and often BASIC) stored permanently in on-board ROM, with the option of loading a more advanced disk operating system from a floppy, whether it be a proprietary system, CP/M, or later, DOS.
By the early 1990s, the increasing size of software meant that many programs demanded multiple diskettes; a large package like Windows or Adobe Photoshop could use a dozen disks or more. Toward the end of the 1990s, distribution of larger packages therefore gradually switched to CD-ROM (or online distribution for smaller programs).
Mechanically incompatible higher-density formats were introduced (e.g. the Iomega Zip drive) and were briefly popular, but adoption was limited by the competition between proprietary formats, and the need to buy expensive drives for computers where the media would be used. In some cases, such as with the Zip drive, the failure in market penetration was exacerbated by the release of newer higher-capacity versions of the drive and media that were not forward-compatible with the original drives, thus fragmenting the user base between new users and early adopters who were unwilling to pay for an upgrade so soon. A chicken or the egg scenario ensued, with consumers wary of making costly investments into unproven and rapidly changing technologies, with the result that none of the technologies were able to prove themselves and stabilize their market presence. Soon, inexpensive recordable CDs with even greater capacity, which were also compatible with an existing infrastructure of CD-ROM drives, made the new floppy technologies redundant. The last advantage of floppy disks, reusability, was countered by re-writable CDs. Later, advancements in flash-based devices and widespread adoption of the USB interface provided another alternative that, in turn, made even optical storage obsolete for some purposes.
An attempt to continue the traditional diskette was the SuperDisk (LS-120) in the late 1990s, with a capacity of 120 MB [3] which was backward compatible with standard 3½-inch floppies. For some time, PC manufacturers were reluctant to remove the floppy drive because many IT departments appreciated a built-in file transfer mechanism that always worked and required no device driver to operate properly. However, manufacturers and retailers have progressively reduced the availability of computers fitted with floppy drives and of the disks themselves. Widespread built-in operating system support for USB flash drives, and even BIOS boot support for such devices on most modern systems, has helped this process along.
External USB-based floppy disk drives are available for computers without floppy drives, and they work on any machine that supports USB Mass Storage Devices. Many modern systems even provide firmware support for booting to a USB-mounted floppy drive. However these drives can't handle anything but the common 80-track MFM format. Which means that formats used by C64, Amiga, Macintosh, etc.. can't be read by these devices.
Windows XP still requires the use of floppy drives to install third-party RAID, SATA, and AHCI hard drives, unless the install CD is modified to include these drivers. Customized Windows XP install CDs can be made with programs such as nLite. This requirement was only dropped with the introduction of Windows Vista in 2007. Most PC motherboards will still attempt to boot from a floppy drive, depending on CMOS settings.
Disk formats
Floppy sizes are almost universally referred to in imperial measurements, even in countries where metric is the standard, and even when the size is in fact defined in metric (for instance the 3½-inch floppy, which is actually 90 mm). Formatted capacities are generally set in terms of binary kilobytes (as 1 sector is generally 512 bytes). For more information see below.
| Disk format | Year introduced | Formatted Storage capacity in KiB (1024 bytes) if not stated | Marketed capacity¹ |
|---|---|---|---|
| 8-inch - IBM 23FD (read-only) | 1971 | 79.7[4] | ? |
| 8-inch - Memorex 650 | 1972 | 175 kB[5] | 1.5 megabit[5] [unformatted] |
| 8-inch - SSSD IBM 33FD / Shugart 901 | 1973 | 237.25[6][7] | 3.1 Mbits unformatted |
| 8-inch - DSSD IBM 43FD / Shugart 850 | 1976 | 500.5[8] | 6.2 Mbits unformatted |
| 5¼-inch (35 track) Shugart SA 400 | 1976[9] | 89.6 kB[10] | 110 kB |
| 8-inch DSDD IBM 53FD / Shugart 850 | 1977 | 980 (CP/M) - 1200 (MS-DOS FAT) | 1.2 MB |
| 5¼-inch DD | 1978 | 360 or 800 | 360 KB |
| 5¼-inch Apple Disk II (Pre-DOS 3.3) | 1978 | 113.75 (256 byte sectors, 13 sectors/track, 35 tracks) | 113 KB |
| 5¼-inch Apple Disk II (DOS 3.3) | 1980 | 140 (256 byte sectors, 16 sectors/track, 35 tracks) | 140 KB |
| 3½-inch HP single sided | 1982 | 280 | 264 kB |
| 3-inch | 1982[11][12] | 360[citation needed] | 125 kB (SS/SD), 500 kB (DS/DD)[12] |
| 3½-inch (DD at release) | 1984 | 720 (400 SS, 800 DS on Macintosh, 880 DS on Amiga) | 1 MB |
| 5¼-inch QD | 720 | 720 KB | |
| 5¼-inch HD | 1982 YE Data YD380[13] | 1,182,720 bytes | 1.2 MB |
| 3-inch DD | 1984[citation needed] | 720[citation needed] | ? |
| 3-inch Mitsumi Quick Disk | 1985 | 128 to 256 | ? |
| 2-inch | 1985[citation needed] | 720[citation needed] | ? |
| 2½-inch | 1986[14] | ? | ? |
| 5¼-inch Perpendicular | 1986[14] | 10 MB | ? |
| 3½-inch HD | 1987 | 1440 | 1.44 MB (2.0 MB unformatted) |
| 3½-inch ED | 1987[15] | 2880 | 2.88 MB |
| 3½-inch Floptical (LS) | 1991 | 21000 | 21 MB |
| 3½-inch LS-120 | 1996 | 120.375 MB | 120 MB |
| 3½-inch LS-240 | 1997 | 240.75 MB | 240 MB |
| 3½-inch HiFD | 1998/99 | 150/200 MB[citation needed] | 150/200 MB |
| Abbreviations: DD = Double Density; QD = Quad Density; HD = High Density; ED = Extended Density; LS = Laser Servo; HiFD = High capacity Floppy Disk; SS = Single Sided; DS = Double Sided | |||
| ¹ The formatted capacities of floppy disks frequently corresponded only vaguely to their capacities as marketed by drive and media companies, due to differences between formatted and unformatted capacities and also due to the non-standard use of binary prefixes in labeling and advertising floppy media. The erroneous "1.44 MB" value for the 3½-inch HD floppies is the most widely known example. See Ultimate capacity and speed. | |||
| Dates and capacities marked ? are of unclear origin and need source information; other listed capacities refer to: Formatted Storage Capacity is total size of all sectors on the disk:
Marketed Capacity is the capacity, typically unformatted, by the original media OEM vendor or in the case of IBM media, the first OEM thereafter. Other formats may get more or less capacity from the same drives and disks. | |||
History
The earliest floppy disks, invented at IBM, were 8 inches in diameter. They became commercially available in 1971.[1][16] Disks in this form factor were produced and improved upon by IBM and other companies such as Memorex, Shugart Associates, and Burroughs Corporation.[17].
In 1976 Shugart Associates introduced the first 5¼-inch FDD and associated media. By 1978 there were more than 10 manufacturers producing 5¼-inch FDDs, in competing disk formats: hard or soft sectored with various encoding schemes such as FM, MFM and GCR. The 5¼-inch formats quickly displaced the 8-inch for most applications, and the 5¼-inch hard-sectored disk format eventually disappeared.
In 1984, IBM introduced the 1.2 megabyte dual sided floppy disk along with its AT model. Although often used as backup storage, the high density floppy was not often used by software manufacturers for interchangeability. In 1986, IBM began to use the 720 kB double density 3.5" microfloppy disk on its Convertible laptop computer. It introduced the so-called "1.44 MB" high density version with the PS/2 line. These disk drives could be added to existing older model PCs. In 1988 IBM introduced a drive for 2.88 MB "DSED" diskettes in its top-of-the-line PS/2 models; it was a commercial failure.
Throughout the early 1980s the limitations of the 5¼-inch format were starting to become clear. Originally designed to be smaller and more practical than the 8-inch format, the 5¼-inch system was itself too large, and as the quality of the recording media grew, the same amount of data could be placed on a smaller surface.[citation needed]
A number of solutions were developed, with drives at 2-inch, 2½-inch, 3-inch and 3½-inch (50, 60, 75 and 90 mm) all being offered by various companies.[citation needed] They all shared a number of advantages over the older format, including a small form factor and a rigid case with a slidable write protection tab. The almost-universal use of the 5¼-inch format made it very difficult for any of these new formats to gain any significant market share.[citation needed]
Sony introduced its own small-format 90.0 mm × 94.0 mm disk.; however, this format suffered from a fate similar to the other new formats: the 5¼-inch format simply had too much market share. A variant on the Sony design, introduced in 1982 by a large number of manufacturers, was then rapidly adopted. By 1988 the 3½-inch was outselling the 5¼-inch[18].
By the end of the 1980s, the 5¼-inch disks had been superseded by the 3½-inch disks. Though 5¼-inch drives were still available, as were disks, they faded in popularity as the 1990s began. By the mid-1990s the 5¼-inch drives had virtually disappeared as the 3½-inch disk became the predominant floppy disk. One of the chief advantages of the 3½-inch disk, besides its smaller size which allows it to fit in a shirt pocket, is its plastic case, which gives it good protection from dust, liquids, fingerprints, scratches, sunlight, warping, and other environmental risks.
Standard floppy replacements
Through the early 1990s a number of attempts were made by various companies to introduce newer floppy-like formats based on the now-universal 3½-inch physical format. Most of these systems provided the ability to read and write standard DD and HD disks, while at the same time introducing a much higher-capacity format as well. There were a number of times where it was felt that the existing floppy was just about to be replaced by one of these newer devices, but a variety of problems ensured this never took place. None of these ever reached the point where it could be assumed that every current PC would have one, and they have now largely been replaced by CD and DVD burners and USB flash drives.
The main technological change was the addition of tracking information on the disk surface to allow the read/write heads to be positioned more accurately. Normal disks have no such information, so the drives use the tracks themselves with a feedback loop in order to center themselves. The newer systems generally used marks burned onto the surface of the disk to find the tracks, allowing the track width to be greatly reduced.
Flextra
As early as 1988, Brier Technology introduced the Flextra BR 3020, which boasted 21.4 MB (marketing, true size was 21,040 KB,[19] 25 MB unformatted). Later the same year it introduced the BR3225, which doubled the capacity. This model could also read standard 3½-inch disks.
Apparently it used 3½-inch standard disks which had servo information embedded on them for use with the Twin Tier Tracking technology.
Original Floptical
In 1991, Insite Peripherals introduced the "Floptical," which used an infra-red LED to position the heads over marks in the disk surface. The original drive stored 21 MB, while also reading and writing standard DD and HD floppies. In order to improve data transfer speeds and make the high-capacity drive usefully quick as well, the drives were attached to the system using a SCSI connector instead of the normal floppy controller. This made them appear to the operating system as a hard drive instead of a floppy, meaning that most PCs were unable to boot from them. This again adversely affected pickup rates.
Insite licenced their technology to a number of companies, who introduced compatible devices as well as even larger-capacity formats. The most popular of these, by far, was the LS-120, mentioned below.
Zip drive
In 1994, Iomega introduced the Zip drive. Although it was not true to the 3½-inch form factor (hence not compatible with the standard 1.44 MB floppies), it still became the most popular of the "super floppies". It boasted 100 MB, later 250 MB, and then 750 MB of storage. Though Zip drives gained in popularity for several years they never reached the same market penetration as standard floppy drives, since only some new computers were sold with the drives. Eventually the falling prices of CD-R and CD-RW media and USB flash drives, along with notorious hardware failures (the so-called "click of death"), reduced the popularity of the Zip drive.
A major reason for the failure of the Zip Drives is also attributed to the higher pricing they carried (partly because of royalties that 3rd-party manufacturers of drives and disks had to pay). However, hardware vendors such as Hewlett Packard, Dell and Compaq had promoted the same at a very high level.[original research?] Zip drive media were primarily popular for the excellent storage density and drive speed they carried, but were always overshadowed by the price.
LS-120
Announced in 1995, the "SuperDisk" drive, often seen with the brand names Matsushita (Panasonic) and Imation, had an initial capacity of 120 MB (120.375 MB)[20] using even higher density "LS-120" disks.
It was upgraded (as the "LS-240") to 240 MB (240.75 MB). Not only could the drive read and write 1440 kB disks, but the last versions of the drives could write 32 MB onto a normal 1440 kB disk (see note below). Unfortunately, popular opinion held the Super Disk disks to be quite unreliable, though no more so than the Zip drives and SyQuest Technology offerings of the same period and there were also many reported problems moving standard floppies between LS-120 drives and normal floppy drives. This belief, true or otherwise, crippled adoption. The BIOS of many motherboards even to this day supports LS-120 drives as boot options.
LS-120 compatible drives were available as options on many computers, including desktop and notebook computers from Compaq Computer Corporation. In the case of the Compaq notebooks, the LS-120 drive replaced the standard floppy drive in a multibay configuration.
Sony HiFD
Sony introduced its own floptical-like system in 1997 as the "150 MB Sony HiFD" which could hold 150 megabytes (157.3 actual megabytes) of data. Although by this time the LS-120 had already garnered some market penetration, industry observers nevertheless confidently predicted the HiFD would be the real standard-floppy-killer and finally replace standard floppies in all machines.
After only a short time on the market the product was pulled, as it was discovered there were a number of performance and reliability problems that made the system essentially unusable. Sony then re-engineered the device for a quick re-release, but then extended the delay well into 1998 instead, and increased the capacity to "200 MB" (approximately 210 megabytes) while they were at it. By this point the market was already saturated by the Zip disk, so it never gained much market share.
Caleb Technology’s UHD144
The UHD144 drive surfaced early in 1998 as the it drive, and provided 144 MB of storage while also being compatible with the standard 1.44 MB floppies. The drive was slower than its competitors but the media were cheaper, running about 8 US$ at introduction and 5 US$ soon after.
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