Floppy disk

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Formats for images of floppy disk data can be found at [[Disk Image Formats]].
 
Formats for images of floppy disk data can be found at [[Disk Image Formats]].
  
−
== 8 Inch ==
+
The main ways in which floppy disks could differ at a recording level:
−
* DEC
+
* The physical dimensions and physical layout – the most common sizes were 8-inch, 5¼-inch (officially the metric 130 mm, but in common parlance referred to by its inch approximation even in countries which normally use the metric system), 3½ inch (likewise officially metric 90 mm, but commonly known by the inch approximation). Note those are the sizes of the actual magnetic disk, the jacket/cartridge is larger. However, there were many other rare sizes.
−
** [[DEC RX01]]
+
* The method of data encoding: the earliest floppies IBM 8-inch floppies used [[FM encoding]]. Capacity was doubled, without changing the disks physically, by switching to the more efficient [[MFM encoding]]. The original FM encoded disks were called "single density", and the MFM encoded "double density". IBM PC 5¼-inch and 3½ inch floppies used MFM encoding; the term "double density" was later extended to "high density" and beyond, but this time it referred to changes in the magnetic material and type of disk heads rather than an encoding change. [[GCR encoding]] was also popular, particularly with systems such as Apple IIs and Commodore 64s. Some early "double density" drives used [[M2FM encoding]] (most notably Intel ISIS-II and HP 9885) which was later replaced by the simpler MFM.
−
** [[DEC RX02]]
+
* Magnetic recording material: more expensive media could store more data
−
* IBM
+
* Type of magnetic disk heads: more expensive magnets could store more data
−
** [[IBM Type 1]] (33FD)
+
* Speed of rotation
−
** [[IBM Type 2]] (43FD)
+
* Constant angular velocity (CAV) versus constant linear velocity (CLV)
−
** [[IBM Type 2D]] (53FD)
+
* Number of sides – early disks and drives were single-sided only and could only record on one side of the disk; later disks and drives were double-sided and supported recording on both sides. There were also "flippy disks" where a single-sided drive could be used to record on both sides of a disk by the user manually flipping the disk to access the other side.
−
** [[IBM 23FD]]
+
* Longitudinal magnetic recording versus perpendicular magnetic recording: traditionally floppies used longitudinal; 2.88 MB floppy drives doubled the capacity over 1.44MB by switching to perpendicular
−
** [[IBM 3740 format]]
+
* Sector size: the earliest floppies had 128 byte sectors; IBM PC floppies normally had 512 byte sectors. IBM PC floppy controllers could support any power of 2 from 128 to 4096. Rarely, different tracks on a floppy could be recorded with different sector sizes, or even a single track with a mix of different sector sizes.
 +
* Gap length between sectors: reducing the gap length could squeeze more sectors on to the disk but at the risk of data loss
 +
* Format of track and sector headers, including CRC algorithms and any per-sector flags (e.g. IBM 3740 has a flag to mark each sector as "deleted", a feature carried forward into IBM PC floppy formats, but almost never used in them.)
 +
* Number of tracks per disk and number of sectors per track
 +
 
 +
A given combination of floppy disk controller, floppy drive, and disk, could generally support several different variations on the same basic format, but only within certain constraints – e.g. IBM PC floppies could be formatted with a non-standard sector size or number of tracks, but not with GCR or MMFM encoding (since the floppy disk controllers used in IBM PCs did not support those encodings).
 +
 
 +
The disk geometry, encoding, etc, is orthogonal to the filesystem – 1.44MB Apple Mac floppies were physically interoperable with IBM PC floppies, even though IBM PCs normally lacked software to read Apple's HFS filesystem; by contrast, the earlier 800KB and 400KB Apple Mac floppies were incompatible with IBM PC floppies, since IBM PC floppy drives could not physically read them, nor could those earlier Mac floppy drives physically read IBM PC floppies.
 +
 
 +
== 2 Inch ==
 +
* [[LT-1]]
 +
* [[Video Floppy]]
 +
 
 +
== 2 1/2 Inch ==
 +
* [[Sharp 2.5-inch floppy disk]]
 +
 
 +
== 3 Inch ==
 +
* [[CF-2 Compact Floppy Disk]]
 +
* [[MCD-1 Micro Cassette]]
 +
 
 +
== 3 1/2 Inch ==
 +
* Acorn
 +
** [[Acorn double density 3 1/2" disk]]
 +
** [[Acorn high density 3 1/2" disk]]
 +
* [[Akai Disk Format]]
 +
* Amiga
 +
** [[Amiga double density disk]]
 +
** [[Amiga high density disk]]
 +
* Apple
 +
** [[Apple double-density 3 1/2" disk]]
 +
** [[Apple high-density 3 1/2" disk]]
 +
* Brother
 +
** [[Brother 120k]]
 +
** [[Brother 240k]]
 +
** [[Brother HD]]
 +
* Commodore
 +
** [[Commodore 1581 disk]]
 +
* IBM PC and compatibles
 +
** [[PC-DOS 720K format]]
 +
** [[PC-DOS 1.44M format]]
 +
** [[PC-DOS 2.88M format]]
 +
* SAM Coupé
 +
** [[SAM Coupé disk]]
 +
* ZX Spectrum
 +
** [[ZX Spectrum Beta Disc 3.5" floppy]] (see [[TR-DOS filesystem]])
 +
 
 +
== 4 Inch ==
 +
* [[IBM DemiDiskette]]
  
 
== 5 1/4 Inch ==
 
== 5 1/4 Inch ==
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** [[Atari 810]]
 
** [[Atari 810]]
 
* CalComp
 
* CalComp
−
** [[CalComp Vistagraphics 4500]]
+
** [[CalComp Vistagraphic 4500 floppy disk]]
 
* Commodore
 
* Commodore
 
** [[Commodore 2040 disk]] (and 4040; for PET computers; preceded 1541 despite higher number)
 
** [[Commodore 2040 disk]] (and 4040; for PET computers; preceded 1541 despite higher number)
Line 53: Line 100:
 
** [[North Star MDS-A-D]]
 
** [[North Star MDS-A-D]]
 
* PMC
 
* PMC
−
** [[PMC MicroMate]]
+
** [[PMC MicroMate floppy disk]]
 
* Tandy
 
* Tandy
−
** TRS-80 Model I, II
+
** TRS-80 Model I, III, 4
 
*** [[TRS-80 single density 5.25" disk]]
 
*** [[TRS-80 single density 5.25" disk]]
 
*** [[TRS-80 double density 5.25" disk]]
 
*** [[TRS-80 double density 5.25" disk]]
 
** TRS-80 Color Computer
 
** TRS-80 Color Computer
−
*** [[TRS-80 Color Computer single density 5.25" disk]]
+
*** [[TRS-80 Color Computer single sided 5.25" disk]]
−
*** [[TRS-80 Color Computer double density 5.25" disk]]
+
*** [[TRS-80 Color Computer double sided 5.25" disk]]
 
* Texas Instruments
 
* Texas Instruments
 
** [[TI-99/4A 90K]]
 
** [[TI-99/4A 90K]]
 
** [[TI-99/4A 180K]]
 
** [[TI-99/4A 180K]]
 
** [[TI-99/4A 360K]]
 
** [[TI-99/4A 360K]]
 +
* ZX Spectrum
 +
** [[ZX Spectrum Beta Disc 5.25" floppy]] (see [[TR-DOS filesystem]])
  
−
== 3 1/2 Inch ==
+
== 8 Inch ==
−
* Acorn
+
[[File:floppy-disks-8in.jpg|thumb|upright|[[Some 8" floppy disks]]]]
−
** [[Acorn double density 3 1/2" disk]]
+
* DEC
−
** [[Acorn high density 3 1/2" disk]]
+
** [[DEC RX01]]
−
* [[Akai Disk Format]]
+
** [[DEC RX02]]
−
* Amiga
+
* IBM
−
** [[Amiga double density disk]]
+
** [[IBM Type 1]] (33FD)
−
** [[Amiga high density disk]]
+
** [[IBM Type 2]] (43FD)
−
* Apple
+
** [[IBM Type 2D]] (53FD)
−
** [[Apple double-density 3 1/2" disk]]
+
** [[IBM 23FD]]
−
** [[Apple high-density 3 1/2" disk]]
+
** [[IBM 3740 format]]
−
* Commodore
+
−
** [[Commodore 1581 disk]]
+
−
* IBM PC and compatibles
+
−
** [[PC-DOS 720K format]]
+
−
** [[PC-DOS 1.44M format]]
+
−
** [[PC-DOS 2.88M format]]
+
−
 
+
−
== 3 Inch ==
+
−
* [[HP 3-inch disk]]
+
  
 
== Data encoding formats ==
 
== Data encoding formats ==
Line 91: Line 131:
 
* [[GCR encoding]]
 
* [[GCR encoding]]
 
* [[MFM encoding]]
 
* [[MFM encoding]]
 +
* [[RLL encoding]]
  
−
== References ==
+
== Devices to read floppy disks ==
  
−
* [http://en.wikipedia.org/wiki/List_of_floppy_disk_formats List of Floppy Disk Formats], Wikipedia.
+
* [http://www.deviceside.com/fc5025.html Device Side Data FC5025 USB 5.25" floppy controller]
 +
* [[KryoFlux]]
 +
* [http://discferret.com/wiki/DiscFerret DiskFerret]
 +
* [http://wiki.icomp.de/wiki/Catweasel Catweasel]
 +
* [http://www.cbmstuff.com/proddetail.php?prod=SCP SuperCard Pro]
 +
* [http://cowlark.com/fluxengine/index.html FluxEngine]
 +
 
 +
== Disk transfer info ==
 +
 
 +
* [http://retro.icequake.net/apple2pc.html Info on disk transfers between Apple II and PC/Mac]
 +
* [http://xfrstn.newmuseum.org/ XFER STN (New Museum)] (available to artists for converting old-format works)
 +
* [http://www.macdisk.com/lecten.php PC-Lect, program to read old disk formats] (for PC/MS-DOS; doesn't work in Windows past Win98)
 +
 
 +
== Utilities ==
 +
 
 +
* [http://disktype.sourceforge.net/ disktype: detect format of disk or disk image]
 +
* [http://digitalcontinuity.org/post/144268258748/floppy-disk-format-identifer-tool Floppy Disk Format Identifer Tool]
 +
 
 +
== Other links and references ==
 +
 
 +
* [[Wikipedia:List of floppy disk formats|List of Floppy Disk Formats]], Wikipedia.
 +
* [http://digitize.archiveteam.org/index.php/Floppy_Disks Digitize the Planet: Floppy Disks]
 
* Michael Haardt et al's [http://www.moria.de/~michael/floppy/ Floppy User Guide] has some information on physical, magnetic, etc formats.
 
* Michael Haardt et al's [http://www.moria.de/~michael/floppy/ Floppy User Guide] has some information on physical, magnetic, etc formats.
 
* [http://www.retrotechnology.com/herbs_stuff/drive.html Floppy drive tech info]
 
* [http://www.retrotechnology.com/herbs_stuff/drive.html Floppy drive tech info]
−
* [http://www.deviceside.com/fc5025.html Device Side Data FC5025 USB 5.25" floppy controller software]
 
 
* [http://archive.org/details/commodore_protection Commodore copy protection books and manuals]
 
* [http://archive.org/details/commodore_protection Commodore copy protection books and manuals]
−
* [http://retro.icequake.net/apple2pc.html Info on disk transfers between Apple II and PC/Mac]
 
 
* [http://www.archiveteam.org/index.php?title=Rescuing_Floppy_Disks Rescuing Floppy Disks (Archive Team)]
 
* [http://www.archiveteam.org/index.php?title=Rescuing_Floppy_Disks Rescuing Floppy Disks (Archive Team)]
 
* [http://archive.org/stream/bitsavers_kaypro3318uideFeb85_2222683/3318-A_Kaypro_Robbie_Users_Guide_Feb85#page/n15/mode/2up Care of diskettes]
 
* [http://archive.org/stream/bitsavers_kaypro3318uideFeb85_2222683/3318-A_Kaypro_Robbie_Users_Guide_Feb85#page/n15/mode/2up Care of diskettes]
 
* [http://vimeo.com/64248011 Floppy disk archaeology lecture (video)]
 
* [http://vimeo.com/64248011 Floppy disk archaeology lecture (video)]
 
* [http://goughlui.com/?p=3239 Dealing with difficult disks and drives]
 
* [http://goughlui.com/?p=3239 Dealing with difficult disks and drives]
−
* [http://xfrstn.newmuseum.org/ XFER STN (New Museum)] (available to artists for converting old-format works)
+
* [http://www.theonion.com/articles/new-improved-obamacare-program-released-on-35-flop,34294/ New, Improved Obamacare Program Released On 35 Floppy Disks (The Onion; humor)]
−
* [http://www.macdisk.com/lecten.php PC-Lect, program to read old disk formats] (for PC/MS-DOS; doesn't work in Windows past Win98)
+
* [http://superuser.com/questions/231273/what-are-the-windows-a-and-b-drives-used-for What are the Windows A: and B: drives used for?]
 +
* [http://ascii.textfiles.com/archives/4226 The Flippy Disk Thing]
 +
* [http://offog.org/notes/archiving/minifloppies/ Imaging 5.25" floppies]
 +
* [http://www.dustbury.com/archives/17950 This could take a while...]
 +
* [http://studioforcreativeinquiry.org/events/warhol-discovery Previously Unknown Warhol Works Discovered on Floppy Disks from 1985]
 +
* [http://studioforcreativeinquiry.org/public/warhol_amiga_report_v10.pdf Detailed report on the Warhol graphic recovery (PDF)]
 +
* [https://twitter.com/mikko/status/460883199690678273/photo/1/large One of the computers that would receive a nuclear launch order from the President still uses 8" floppy disks.]
 +
* [http://www.loc.gov/preservation/resources/rfs/softgame.html Library of Congress Recommended Format Specifications: Software/Gaming]
 +
* [http://qanda.digipres.org/199/settings-should-imaging-floppy-disks-using-kryoflux-device What settings should be used when imaging floppy disks using a Kryoflux device?]
 +
* [https://docs.google.com/spreadsheets/d/1g_xM_cmUAl2AIYwD3d_2IulZlOG6_JmDDf7FoIRW9EM/edit Spreadsheet of floppy formats and Kryoflux settings]
 +
* [https://github.com/euanc/kryofluxDiskID Kryoflux Disk ID software; tries to identify disk types in image]
 +
* [http://www.openplanetsfoundation.org/blogs/2014-06-26-bulk-disk-imaging-and-disk-format-identification-kryoflux Bulk disk imaging and disk-format identification with KryoFlux]
 +
* [http://www.sugarcayne.com/2013/09/exile-zip-disks-floppies/ Zip Disks & Floppies: musical piece by artist who formerly used those media for storing beats]
 +
* [http://dmweb.free.fr/?q=node/210 Notes on copy protection of Dungeon Master and Chaos Strikes Back for Atari ST and Amiga]
 +
* [http://news.softpedia.com/news/Windows-10-Preview-Removes-Floppy-Disk-Drive-Support-468177.shtml Windows 10 Preview Removes Floppy Disk Drive Support]
 +
* [http://forum.kryoflux.com/viewtopic.php?f=3&t=630&hilit=8+inch Some discussion of Shugart 801 8" drive]
 +
* [http://www.macworld.com/article/3018315/storage/star-trek-creators-lost-words-recovered-from-old-floppies.html How Star Trek creator Gene Roddenberry’s words were freed from old floppy disks]
 +
* [http://openpreservation.org/blog/2016/09/01/an-8-floppy-disk-challenge/ An 8″ Floppy Disk Challenge]
 +
* [http://openpreservation.org/blog/2016/09/02/digital-obsolescence-reproducing-data-cables/ Digital Obsolescence: Reproducing Floppy Data Cables]
 +
* [https://www.youtube.com/watch?v=EHRc-QMoUE4 The 8-Bit Guy: How Old School Floppy Drives Worked] (video)
 +
* [http://journal.code4lib.org/articles/11986 Working with Floppy Disks from the 1980s]
  
 
See also [[Disk Imaging Software & Systems]].
 
See also [[Disk Imaging Software & Systems]].

Latest revision as of 11:41, 5 September 2024

See also Filesystems, which are contained on Floppy Disks.
File Format
Name Floppy disk
Ontology

Some floppies, 5 1/4" and 3 1/2".

Some floppies, 5 1/4" and 3 1/2".

Formats for images of floppy disk data can be found at Disk Image Formats.

The main ways in which floppy disks could differ at a recording level:

  • The physical dimensions and physical layout – the most common sizes were 8-inch, 5¼-inch (officially the metric 130 mm, but in common parlance referred to by its inch approximation even in countries which normally use the metric system), 3½ inch (likewise officially metric 90 mm, but commonly known by the inch approximation). Note those are the sizes of the actual magnetic disk, the jacket/cartridge is larger. However, there were many other rare sizes.
  • The method of data encoding: the earliest floppies IBM 8-inch floppies used FM encoding. Capacity was doubled, without changing the disks physically, by switching to the more efficient MFM encoding. The original FM encoded disks were called "single density", and the MFM encoded "double density". IBM PC 5¼-inch and 3½ inch floppies used MFM encoding; the term "double density" was later extended to "high density" and beyond, but this time it referred to changes in the magnetic material and type of disk heads rather than an encoding change. GCR encoding was also popular, particularly with systems such as Apple IIs and Commodore 64s. Some early "double density" drives used M2FM encoding (most notably Intel ISIS-II and HP 9885) which was later replaced by the simpler MFM.
  • Magnetic recording material: more expensive media could store more data
  • Type of magnetic disk heads: more expensive magnets could store more data
  • Speed of rotation
  • Constant angular velocity (CAV) versus constant linear velocity (CLV)
  • Number of sides – early disks and drives were single-sided only and could only record on one side of the disk; later disks and drives were double-sided and supported recording on both sides. There were also "flippy disks" where a single-sided drive could be used to record on both sides of a disk by the user manually flipping the disk to access the other side.
  • Longitudinal magnetic recording versus perpendicular magnetic recording: traditionally floppies used longitudinal; 2.88 MB floppy drives doubled the capacity over 1.44MB by switching to perpendicular
  • Sector size: the earliest floppies had 128 byte sectors; IBM PC floppies normally had 512 byte sectors. IBM PC floppy controllers could support any power of 2 from 128 to 4096. Rarely, different tracks on a floppy could be recorded with different sector sizes, or even a single track with a mix of different sector sizes.
  • Gap length between sectors: reducing the gap length could squeeze more sectors on to the disk but at the risk of data loss
  • Format of track and sector headers, including CRC algorithms and any per-sector flags (e.g. IBM 3740 has a flag to mark each sector as "deleted", a feature carried forward into IBM PC floppy formats, but almost never used in them.)
  • Number of tracks per disk and number of sectors per track

A given combination of floppy disk controller, floppy drive, and disk, could generally support several different variations on the same basic format, but only within certain constraints – e.g. IBM PC floppies could be formatted with a non-standard sector size or number of tracks, but not with GCR or MMFM encoding (since the floppy disk controllers used in IBM PCs did not support those encodings).

The disk geometry, encoding, etc, is orthogonal to the filesystem – 1.44MB Apple Mac floppies were physically interoperable with IBM PC floppies, even though IBM PCs normally lacked software to read Apple's HFS filesystem; by contrast, the earlier 800KB and 400KB Apple Mac floppies were incompatible with IBM PC floppies, since IBM PC floppy drives could not physically read them, nor could those earlier Mac floppy drives physically read IBM PC floppies.

Contents

[edit] 2 Inch

[edit] 2 1/2 Inch

[edit] 3 Inch

[edit] 3 1/2 Inch

[edit] 4 Inch

[edit] 5 1/4 Inch

[edit] 8 Inch

Some 8" floppy disks

[edit] Data encoding formats

[edit] Devices to read floppy disks

[edit] Disk transfer info

[edit] Utilities

[edit] Other links and references

See also Disk Imaging Software & Systems.

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