Example of a floppy disk
(here: 90 mm [3.5 ″] diskette)
|Type||magnetic data carrier|
|capacity||80 KiB (8 ″)
to 3250 KiB (3.5 ″ ED)
|lifespan||about 5 to 30 years|
|size||200 mm (8 ″ disk)
130 mm (5.25 ″ disk)
90 mm (3.5 ″ disk)
80 mm (3 ″ disk)
|developer||Alan Shugart (IBM)|
|successor||CD , MOD , PD , Iomega Zip , USB sticks|
A floppy disk is a magnetic data carrier . Its basic component consists of a thin, flexible plastic disc made of boPET . This disk is coated with a magnetizable material, usually iron oxide, whose storage principle is similar to that of the hard disk . Initially only enclosed by a square cardboard cover with a reading window, a 3.5 ″ data carrier is better protected by a solid, rectangular plastic housing with a window lock. The English term " floppy disk " or simply " floppy ", which would be to transfer about with "wobbly slice" into German, is based on the flexible property of the storage medium, as opposed to hard disk ( "fixed disk") of a hard disk drive ( English hard disk drive ).
In contrast to the hard disk, the magnetic head (read / write head) on a floppy disk rubs directly on the coated magnetizable surface, which over time leads to significant abrasion and severely limits the long-term usability of floppy disks. In addition, the magnetic disk rubs directly against the surrounding case, which is firmly in the drive. Therefore, the inside of this cover is provided with Teflon -coated (or similar) fabric to minimize friction.
The format (in the sense of physical size) of floppy disks is mainly given in inches (″), common sizes were and are:
- 8 ″ (actually 200 mm ) with 180 KiB for diskettes - the original diskette format from IBM as a replacement for unwieldy stacks of punched cards , later with up to 1 MiB
- 5.25 ″ (actually 130 mm) with 80 to 1200 KiB (160 KiB for the first IBM PC )
- 3.5 ″ (actually 90 mm) with 360 to 1440 KiB ≈ 1.4 MiB (HD disks, most recently the standard format of many systems), rarely up to 3520 KiB ≈ 3.4 MiB (ED disks formatted with 44 sectors ). The plastic cover is 90 mm wide, 94 mm long and 3.5 mm high.
- 3 ″ (actually 80 mm) with 180 KiB per page (including Schneider / Amstrad CPC , Joyce and Oric Atmos )
In addition, other sizes such as B. 3.25 ″ and 2 ", but these could not prevail. An exception was the video floppy in 2" format developed by Sony , which was used, among other things, in the original analog version of the Sony Mavica cameras and still video -Cameras were used:
2 "video floppy from Canon
The standards for 3.5 "disks are ISO / IEC 8860-1: 1987 (twice the density), ISO / IEC 9529-1: 1989 (high density, English , high density ') and ISO / IEC 10994-1: 1992 (extra-high density); all information is given in metric units. These standards clarify the measurements that result in 90.0 × 94.0 × 3.3 mm. The magnetic disc inside has a diameter of exactly 86.0 mm.
A distinction is made as follows:
- Disks written on one and two sides
- SS: single sided , alternative designations: 1S, 1
- DS: double sided, alternative designations: 2S, 2
- the recording density resulting from the magnetic material used
- hard - or soft -sektoriert - so hard or soft in data blocks divided
With hard-sectored floppy disks there is one index hole per sector on the plastic disc, with the much more widespread soft-sectored floppy disks only one at all, or an asymmetrical drive access in the middle. This index hole or the asymmetry defines the starting point of a track, provided it is not ignored by the drive (soft synchronization: recognition of the beginning of the track through a sequence of synchronization bits).
Most used magnetic layer materials:
- DD: 2 µm iron oxide , coercive field strength around 24,000 A / m
- HD: 1.2 µm cobalt- doped iron oxide, coercive field strength around 48,000 A / m
- ED: 3 µm barium ferrite , coercive field strength around 60,000 A / m
The exact specification of a floppy disk also includes further information:
- the number of magnetic tracks, the "tracks" (initially usually 35, later typically 40 or 80)
- the number of sectors, i.e. blocks per track, (e.g. 9 or 18)
- the block size (previously 128, 256, 512 or 1024 bytes, today mostly only 512 bytes; many controllers also support 1 and 8 KiB sectors)
- the recording method (initially FM , later mostly MFM ; Apple and Commodore also used the GCR method)
- the track density, usually 48, 96 or 135 tpi ( Tracks Per Inch ). Commodore used the deviating value of 100 tpi on some drives, which made these floppy disks physically unreadable for external drives.
It is technically possible to accommodate a different number of sectors depending on the track, especially since there is theoretically more space on the outer tracks; however, since the relative speed of the head is also higher there, this encountered difficulties. Some manufacturers therefore varied either the speed of rotation (Apple, Victor / Sirius) or the data rate (Commodore) depending on the head position, which allowed more to be stored on the floppy disk, but made it incompatible with drives from other manufacturers.
One trick to increase the access speed was the so-called interleaving , whereby the sectors were not recorded numerically in ascending order, but in a different order on a track. In this way, for example, the technically necessary post-processing of a read process could be carried out, and immediately afterwards the offset logically next sector could be read. The ideal interleave rate depends on the hardware.
Similarly, the idea was to arrange the logically first sector of a track slightly offset from the neighboring tracks, so that when reading successive tracks after a track change, during which the floppy disk rotates a little further, this sector arrives just below the read head, so that can be read on immediately.
Floppy disks have write protection which, with 3.5 ″ disks, can be switched on and off using a small slide at the top right at the back (open = write protection). With 5.25 ″ and 8 ″ floppy disks, a write protection recess at the edge (with 8 ″ on the front, with 5.25 ″ on the side) must be sealed with a dark write protection sticker (closed = write protection). The write protection is detected in the drive by a mechanical switch or a light barrier that interrupts the power to the write head; it is intended that the write protection cannot be bypassed by software. Original diskettes from commercially available software often lacked this slider or this recess from the outset, so that they are always write-protected. The missing slider on the 3.5 ″ floppy disks can also be replaced with transparent adhesive tape, since the write protection test is carried out mechanically on these disks.
Data transfer rate
5.25 "-HD- and 8" disks rotate normally with 360 min -1 , 5.25 "-DD-, 3" - and 3.5 "disks 300 min -1 .
With SD disks, the data is transmitted at 125 kbit / s, with DD disks it is 250 kbit / s, with HD disks 500 kbit / s, and with ED disks 1 Mbit / s is possible.
Although some manufacturers of HD floppy disks advertised a theoretical service life of up to 100 years, this value can only be achieved when stored under specific environmental conditions. If it is adequately shielded from heat, sun and magnetism, storage times of 10 to 30 years should be possible. Experience has shown that floppy disks with a lower write density can be stored for decades in a dry place. To protect them from contamination, 5.25 "and 8" floppy disks are usually stored in a paper or cardboard bag that is included with the diskette. With constant use, floppy disks are subject to greater stress due to the mechanical read and write head in the disk drive. In the worst case, floppy disks show defects after one to two years.
With some older floppy disks, the coating can slowly peel off and contaminate the read / write head when used in the drive. This depends on the manufacturer and if you look closely at the surface, such changes are often visible beforehand. The read / write head can usually be cleaned again with an alcohol solution. There are also special cleaning disks.
Floppy disk drives
Table overview of the disk formats
As a result of the increasing dominance of IBM-compatible PCs , the FAT12 file system developed by Microsoft and used by IBM established itself as the standard for floppy disks from 1981, and floppy disks that were already pre-formatted with FAT12 at the factory were increasingly being sold. The FAT12 file system is still in use for floppy disks under Microsoft Windows , but other operating systems (such as Linux ) have long been able to read and write data carriers in this format.
|format||Publishing year||Capacity in KiB
(unless otherwise stated)
|different capacities specified in stores|
|8 ″ SS (read-only)||1971||80|
|8 ″ SS||1973||256|
|8 ″ SS||1974||800|
|8 ″ DS||1975||1000|
|5.25 ″ SS||1976||110|
|5.25 "DS, SD||1977||180|
|5.25 "DS, DD||1978||360|
|5.25 "DS, QD||1982||720|
|5.25 "DS, HD||1984||1200|
|3 ″ SD||1982||360|
|3.5 ″ SS, DD||1983||360|
|3 ″ DD||1984||720|
|3.5 ″ DS, DD||1984||720|
|3.5 ″ HD||1987||1440||"1.44 MB"|
|3.5 "ED||1991||2880||"2.88 MB"|
|3.5 ″ LS-120||1996||120375|
|3.5 ″ LS-240||1997||240750|
|3.5 ″ HiFD||1998/99||150000/200000|
|Abbreviations: SS = Single Sided; DS = Double Sided; SD = single density; DD = double density; QD = Quad Density; HD = high density; ED = extra-high density; LS = laser servo; HiFD = high capacity floppy disk|
|The listed storage capacities refer to:
With other formats, the storage capacity that can be achieved with the same drives and floppy disks may vary. For example, there are programs for MS-DOS such as HD-COPY, VGA-COPY or 2MGUI with which, for example, 3.5 ″ HD disks with more than 1440 KiB can be formatted (e.g. 1.722 MiB). On Linux this is also possible with fdformat. AmigaOS (1.76 MiB) and MacOS format with more than 1440 KiB.
Usable file systems (examples)
Not every file system can be used on every data carrier. While z. B. FAT12 was developed for floppy disks and could also be used on hard disk partitions up to 16 MiB (up to the 1980s), the definition of cylinders was added with FAT16. Although the cylinders of the hard drives coated on one side, which were common at the time, were identical to the track, the FAT16 / 32 and NTFS drivers at least require the support of cylinders in the drive's control electronics. Such file systems are therefore - in contrast to the electronics of solid-state drives , which were explicitly designed as a replacement for hard disks - without supporting control electronics, not downwardly compatible with floppy disks. This came into use only with the later SuperDisk and Zip disk drives .
|File system||primary supported operating systems|
|FAT12||DOS , Windows , Atari TOS|
|UFS||BSD family, Solaris|
In practice, the widespread use of DOS and Windows operating systems has resulted in FAT12 being the dominant file system on floppy disks. FAT12 is supported as a compatible file format for file exchange on most other operating systems. Special devices with floppy drives such as typewriters (see Brother LW series ) or keyboards and later floppy emulators also support FAT12.
After exchangeable disk stacks or individual hard disks from 1956, IBM launched the first diskette (with a disk diameter of 200 mm, ≈ 8 ″) with the associated drive for the System / 370 computer series in 1969 . This drive could only read and not write to floppy disks and was therefore only used to make new versions of the IBM system software available to users at a lower price. For the day-to-day work, the expensive and space-consuming punch cards, punched strips and magnetic tapes initially remained common. The invention of the floppy disk is commonly attributed to Alan Shugart . The capacity of the first disk was exactly 80 Kibibyte (at that time usually abbreviated as "KB"), which corresponded to 1000 punch cards , a sales unit that was common at the time.
In 1972 the Memorex company brought the first floppy disk drive with write capability to the market, again developed by Shugart; this began the gradual replacement of punched cards, punched tapes and magnetic tapes. Shugart founded his own company ( Shugart Associates ) in 1973 and developed the so-called 5.25 ″ diskette (disk diameter 130 mm, ≈ 5.25 ") in 1976. In 1978 TEAC presented the world's first 5.25 ″ diskette drive; for The then new microcomputers took up the new format immediately, for mainframes a little later. In 1981 Sony presented the so-called 90 mm floppy disk in a rigid housing, initially on one side with 360 KiB, later on both sides with 720 KiB (737,280 bytes in 9 sectors ) and then 1440 KiB (1,474,560 bytes in 18 sectors). Its disk diameter is 85 mm, but its plastic housing is 90 mm wide. Later it was mainly referred to as a 3.5 ″ disk - in accordance with the other disk sizes.
Many other systems used the same floppy disks, but with different recording formats and / or file systems . For example, a 3.5 ″ HD disk from an Amiga computer formatted with FFS holds 1.76 MiB, but 3.5 ″ diskettes that were formatted with around 880 KiB were usually used there. Later so-called ED disks with 2880 KiB (36 sectors) appeared. The latter were mainly used in computers from NeXT and the PS / 2 series from IBM, but were not widely used beyond that.
The 1440 KiB floppy disk remained the common standard through the 1990s. It was pushed into the background towards the end of the decade, because the amount of data was increasing and no open standards for floppy disks of larger capacity were developed. Software was often sold on pressed CDs . Until CD burners became affordable and data exchange over the Internet became widespread, diskette-like products with higher capacities from individual manufacturers gained a certain degree of popularity, especially the Zip drive , but also the SuperDisk .
At least since flash memories have become inexpensive and most computers can at least read and write to USB sticks without any problems, the floppy disk has practically no market significance and no more applications. However, Sony still sold 12 million units in Japan in 2009 with a market share of 70%, but announced the end of production for March 2011. Verbatim will thus be the last producer of floppy disks, which are mainly sold in the successor states of the former Soviet Union .
Even today there is still a small market for older synthesizers and samplers , as floppy disks were often used for these as storage media for the sound data, e.g. B. the Roland S-50. In contrast to older computers, these musical instruments are still used productively more often. For them there are now drive emulators for replacing the floppy disk drive, which can store up to 100 virtual floppy disks on a USB stick (→ alternatives). With devices that have the option of MIDI dump , the sound data can also be transmitted in this way.
- From 1991 onwards, Insites floptical drives with 21 MiB storage capacity on special 3.5 ″ floppy disks were used in certain niches. Conventional 3.5 ″ -DD and HD floppy disks could be read and written. The drive was integrated via SCSI , optionally the drive was also bootable. Due to the very high price and the comparatively complicated connection, the system could not establish itself on the mass market.
- At times, Zip drives (100 MB , later 250 MB and finally 750 MB) were installed as replacement floppy drives in IBM-compatible PCs and, above all, Apple computers . In PCMCIA-enabled laptops and cameras, there was also a smaller version called the Iomega Clik! with 40 MB storage capacity. Especially in DTP region were removable hard drives from SyQuest with initially 44 MB, widespread later up to 270 MB. Despite widespread acceptance, Zip drives could not establish themselves in the long term because they could not keep up with the storage capacity of the writable optical media that were being developed in parallel.
- The SuperDisk drives (LS120 and LS240) were less successful . In addition to special storage media with servo tracks, normal 3.5 ″ floppy disks with a capacity of 1440 KiB or 720 KiB could also be used, some of which could be read significantly faster than in conventional drives. The 240 MB drive could also store up to 32 MiB on normal 1440 KiB HD floppy disks using special packet writing software.
- In 1998, Sony tried to replace the current drives with a HiFD floppy disk drive that could read and write floppy disks with 150 MB, from 1999 with 200 MB, and which was compatible with the 1440 KiB HD disk. The data storage version of the MiniDisc (MD-Data) with 140 MB capacity presented by Sony in 1991 and the Hi-MD (300 MB or 1 GB) presented in 2004 were also rarely used as removable media. At MD-Data, this was also due to Sony's restrictive licensing policy, which made the standard unattractive for third-party manufacturers.
- Also in 1998 Caleb tried in vain to establish itself with UHD144 drives. These could store 144 MB on special floppy disks and also read and write normal 1440 KiB floppy disks.
However, none of these improved versions of the original 3.5 ″ floppy disk drive could become more widespread. In the meantime, they too have become obsolete in terms of storage capacity and speed.
Since 2004/2005, even IBM-compatible PCs have increasingly often no longer have built-in floppy drives. Instead, you can connect external floppy disk drives to the USB interface, but these are not included in the scope of delivery of new devices and often do not support reading and writing of HD floppy disks other than 1440 KiB formatted. Often the necessary controller for floppy drives is still available on the mainboard, so that you can then install a floppy drive yourself. Such controllers on plug-in cards have not been available since the 1990s because the DMA signals of the ISA bus required for this are missing on the PCI bus and also on PCI Express . The floppy disk drive controllers on newer PC mainboards are connected to the processor via the LPC bus ; From a software point of view, LPC is an ISA-compatible bus, which, however, requires fewer lines and does not have any slots.
Since 2002/2003, with the availability of the sufficiently fast USB 2.0 connection, USB sticks ( flash memory ) and other external USB and FireWire mass storage devices such as hard drives and DVDs have been increasingly used as data carriers. However, the necessary capabilities for a complete replacement of the floppy disk on this basis, especially bootability , were only given a few years later.
There are some models of USB sticks in which the storage area is divided into two parts: The first storage area corresponds in organization and capacity to a 3.5 ″ HD floppy disk that is formatted with the FAT12 file system (1440 KiB, 80 tracks with 18 Sectors per track and 512 bytes per sector). This area can therefore be used directly as a virtual boot disk. The second, much larger storage area is organized as a so-called removable disk, as is the case with all other USB sticks.
For older synthesizers and program-controlled machines, there are hardware- compatible floppy disk emulators in the usual 3.5 ″ drive size with a front connection for USB memory sticks. Up to 100 disk images of the formats 720 KiB, 1200 KiB or 1440 KiB can then be saved on this. One of the virtual floppy disks can then be selected using buttons and a two-digit display on the emulator. To manage the content on a desktop computer, either such an emulator can be connected, or the usual USB port can be used, after which the desired virtual floppy disk can be written using software. More specialized systems can also emulate 8 ″ disks or 3.5 ″ special formats and work with a CF card or over a network.
Examples of recent use cases
- In 2015, Norwegian doctors still often sent patient data to authorities on 3.5-inch diskettes by post. The government wants to change the system from 2016.
- According to CBS in 2014, 8-inch floppy disks were still used in mainframes in US nuclear weapons storage facilities for data exchange. In 2019, this process began to be converted to SSD data carriers.
- The New York Times reported in 2013 that the Federal Register, the official gazette of the US government, still transmits some data on 3.5-inch diskettes. USB sticks are not allowed and secure internet connections are more complex.
- Various music publishers also publish individual labels on 3.5-inch disks. The largest label in the field is Floppy Noise Records from Ukraine, which is a sub-label of Depressive Illusions Records and only releases on 3.5-inch floppy disk.
- The information about seat reservations on Deutsche Bahn trains was still transmitted to the trains in 2015 by diskette.
- Other examples include the control of industrial equipment such as weaving and sewing machines that were manufactured during the 1990s. The machines were designed for a service life of several decades. It is often cheaper for companies to keep floppy disks and disk drives in operation than equipping the machines for network connections.
- Critical software updates in Boeing 747 aircraft will still be imported via floppy disk in 2020.
Long after the disappearance of disk drives in most modern PCs is the disk, usually as a 3.5-inch disk, continue on almost all operating systems and many application programs as a symbol, English Icon , for saving files to find. Because younger people have often not experienced the era of floppy disk drives on computers, they sometimes only know floppy disks as the save symbol in menus and toolbars . Together with the advent of 3D printers , the joke developed in which the father holds a floppy disk in his hand and the son comments on this with the following words: "Cool, you printed the save symbol!"
Although there were repeated attempts in the 2000s to replace the floppy disk as the save symbol with something more modern, it can still be found in e.g. B. Microsoft Office .
- Long-term archiving - about the problem of the "expiry" of disk contents
- CopyWrite - a program for exact diskette copies under DOS
- ISO - ISO standards for floppy disks
- The floppy user guide - Comprehensive description of floppy disks and drives
- The capacities of floppy disks are noted in a mixture of powers of two and powers of ten. For floppy disks, "KB" usually stands for the unit of 2 10 = 1024 bytes, also known as KiB and Kibibyte . "MB" stands for 1000 or 1024 KiB for floppy disks, depending on the type. In this article, “KiB” and “MiB” are used to mean 1024 bytes and 1024 KiB, respectively, and “KB” and “MB” are used to mean 1000 bytes and 1000 KB, respectively, unless otherwise specified.
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