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List of floppy disk formats

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For a more in-depth textual description of some of these formats, see Floppy disk variants.

8-inch, 5+1⁄4-inch, and 3+1⁄2-inch floppy disks

This is a list of different floppy disk formats.

Physical formats

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Size Density Sides Tracks tpi bpi Sectoring Coercivity Unformatted capacity per side
2 inch Video Floppy 52 256 >800 kB or 50 fields of analog video[1]
2 inch LT-1 double 80 245
21⁄2 inch Single 16[2][3] 48[2] 64 kB
3 inch QuickDisk
3.25 inch single 1 80[4] 140 4,625 250 kB
double 9,250 500 kB
31⁄2 inch Single 2 40[5] 67.5 8,650 soft 665 Oe 250 kB[citation needed]
Double 80 135 8,717 665 Oe[6] 500 kB[citation needed]
High 80 135 17,434 720-750 Oe 1 MB
Extended 80 135 34,868 900 Oe 2 MB
Triple[7] 240[8] 406.5[8] 36,700[8] 6.5 MB
4 inch DemiDiskette 1[9]
51⁄4 inch Single/Double 2 40 48 5,876 soft or hard 300 Oe 250 kB
Quad 77 100 300 Oe 500 kB (Micropolis-compatible)
Quad 80 96 5,922 300 Oe 500 kB
High 80 96 9,646 soft 600 Oe 833 kB
EH[10] 104 125 29,560 6.5 MB[11]
51⁄4 inch

Apple FileWare

Double 2 80 62.5 soft 851 kiB[12]
8 inch Single 77 48 3,268-3,408 soft or hard (inner edge) 300 Oe 1 MB
Double 6,816 1 MB
HD[13] 154 96 20,560 600 Oe 9.6 MB[14]
8 inch Memorex FD 650 1[15] 50[15] 2,400 hard (outer edge) 1.5 Mb[15]
651 64[16] 3,100 2.5 Mb[16][17]
8 inch Burroughs Double 2 139 150 7,100 2[18]

Logical formats

[edit]

Throughout the 1970s and 1980s, many different logical disk formats were used, depending on the hardware platform.

Common floppy disk formats, logical characteristics by platform
Platform Size Density Sides Tracks/ side Sectors/ track Bytes/ sector Sectoring Capacity rpm Encoding Note
Acorn 51⁄4 inch Single 1 40 10 256 soft 100 kB 300 FM
80 200 kB
Double 1 40 16 256 160 kB MFM
80 320 kB
2 640 kB
31⁄2 inch Double 2 80 16 256 640 kB 300 MFM Format L: MOS (Electron, Master Compact)
5 1024 800 kB
  • Format D: Arthur, RISC iX
  • Format E: RISC OS
High 10 1,600 kB Format F: RISC OS 3 and later. Archimedes models before the A5000 require an upgraded floppy drive.
Agat 51⁄4 inch Double 2 80 21 256 840 kB 300 MFM [NB 1]
Amstrad CPC/PCW 3 inch Double 1 40 9 512 180 kB 300 MFM Single head drive, but double-sided floppy discs (total of 360 kB per floppy)
Amstrad PCW8512/9512 3 inch Double 2 80 9 512 720 kB 300 MFM 720 kB mode uses both sides - ensure disc inserted correct way up.
Apple II 51⁄4 inch Double 1 35 13 256 soft 113.75 kB 300 GCR [NB 2]
1 16 140 kB
31⁄2 inch Double 1 80 Variable (8-12) 512 400 kB 394 - 590 GCR [NB 3]
2 800 kB
High 2 80 18 512 1,440 kB 300 MFM [NB 4]
Apple Lisa 51⁄4 inch FileWare Double 2 46 Variable (15-22) 512 soft 851 kB 218 - 320[19] GCR
Apple Lisa 2/Macintosh XL,

Macintosh

31⁄2 inch Double 1 80 Variable (8-12) 512 soft 400 kB 394 - 590 GCR
Apple Macintosh 2 800 kB
High 2 80 18 512 1,440 kB 300 MFM
Atari 8-bit 51⁄4 inch Single 1 40 18 128 soft 90 kB 288 FM [NB 5]
Dual 26 128 130 kB MFM
Double 18 256 180 kB
Double 2 18 256 360 kB 300
Atari ST/TT/Falcon 31⁄2 inch Double 1 80 9 512 soft 360 kB 300 MFM
2 720 kB
High 18 1,440 kB
Coleco ADAM 51⁄4 inch Double 1 40 8 512 soft 160 kB 300 MFM
Commodore 64 (8-bit) 51⁄4 inch Double 1 35 Variable (17-21) ZCAV 256 soft 170 kB 300 GCR [NB 6]
2 340 kB
Quad 1 77 Variable (23-29) ZCAV 521 kB
2 1,042 kB
31⁄2 inch Double 2 80 10 512 800 kB MFM  
Commodore Amiga 51⁄4 inch Double 2 40 11 512 soft 440 kB[NB 7] 300 MFM [NB 8]
Quad 80 880 kB[NB 9]
31⁄2 inch Double 880 kB
High 19 1,520 kB GCR [NB 10]
22 1,760 kB 150 MFM [NB 8]
Commodore 900 51⁄4 inch High 2 80 13-16 512 Soft 1,200kB ? GCR https://vintagecomputer.ca/files/Commodore/C900/C900%20Floppy%20Specification.pdf
IBM 33FD 8 inch Single 1 77 26 128 240.5 kiB 360 FM Diskette 1[20]
15 256 277.5 kiB
8 512 296 kiB
IBM 43FD 2 26 128 481 kiB Diskette 2[20]
15 256 555 kiB
IBM 53FD Double 26 256 962 kiB MFM Diskette 2D[20]
15 512 1.08 MiB
8 1,024 1.16 MiB
DEC RX01 8 inch Single 1 77 26 128 250 kB 360 FM
DEC RX02 8 inch Double 1 77 26 256 500 kB 360 FM/MFM
DEC RX50 51⁄4 inch Quad 1 80 10 512 400 kB 300 MFM
IBM PC compatibles[21] 8 inch Single 1 77 26 128 soft 250.25 kB[NB 11][21][22][23] 360 FM [NB 12]
2 500.5 kB[NB 11][21][22][23]
Double 1 8 1,024 616 kB[NB 11][22][23] MFM
2 1,232 kB[NB 11][21][22][23]
51⁄4 inch Double 1 40 8 512 160 kB[NB 11] 300 MFM  
2 320 kB[NB 11]
1 9 180 kB[NB 11]
2 360 kB[NB 11]
Quad[NB 13] 1 80 8 320 kB[NB 11] 300
2 640 kB[NB 11]
High 2 80 15 1,200 kB[NB 11] 360
31⁄2 inch Double 1 80 8 512 320 kB[NB 11] 300 MFM
9 360 kB[NB 11]
2 8 640 kB[NB 11]
9 720 kB[NB 11]
High 18 1,440 kB[NB 11]
21 1,680 kB[NB 11] DMF[NB 14]
82 1,720 kB[NB 11]
Extended 80 36 2,880 kB[NB 11]
MGT SAM Coupé 31⁄2 inch Double 2 80 10 512 800 kB 300 MFM  
NEC PC98 8 inch Single 1 77 26 128 250.25 kB[NB 11] 360 FM  
Double 2 77 8 1,024 1,232 kB[NB 11] MFM
51⁄4 inch Double 2 80 8 512 640 kB[NB 11] 360 MFM
9 720 kB[NB 11]
High 15 1,200 kB[NB 11]
77 (80)[NB 15] 8 1,024 1,232 (1,280) kB[NB 11][NB 15] [NB 15]
31⁄2 inch Double 2 80 8 512 640 kB[NB 11] 360 MFM
9 720 kB[NB 11]
High 15 1,200 kB[NB 11] 3-mode[NB 16][NB 15]
77 (80)[NB 15] 8 1,024 1,232 (1280) kB[NB 11][NB 15]
80 18 512 1.44 MB[NB 11] 300
Triple 240 38 512 9,120 kB 360 NEC PC-88 VA3 2TD drive only[8][7]
Osborne 1[24] 51⁄4 inch Single 1 40 10 256 soft 100 kB 300 FM
Double 5 1,024 200 kB MFM
Sega SF-7000 3 inch Single 2 40 16 256 160 kB ? ? Expansion unit for SC-3000 home computer. Capacity is per side.

[25]

SHARP X68000 51⁄4 inch High 2 77 8 1,024 1,232 kB[NB 11] 360 MFM  
31⁄2 inch
SHARP CE-1600F, CE-140F 21⁄2 inch[2][3] Single drive: 1, diskette: 2 (flippable) 16 8 512 2× 64 kB 270 GCR (4/5) Internally based on FDU-250 Micro Floppy Disk Drive Unit[2]
Thomson 51⁄4 inch Single 1 40 16 128 80 kB 300 FM Thomson UD90.070
Double 2 256 320 kB MFM Thomson DD90-320[NB 17]
31⁄2 inch Double 1 80 16 256 320 kB 300 MFM Thomson TO9, Thomson DD09-350
Double 2 640 kB Thomson TO8D, TO9+, Thomson DD90-352[NB 18]
Victor 9000 / ACT Sirius 1[26] 51⁄4 inch Single 1 80 11-19 (variable) 512 612 kB[27] 252-417 (variable) GCR Disks varied sectors / track and disk speed to keep consistent bit density across tracks[26]
Double 2 512 1,196 kB[27]
Tandy TRS-80 51⁄4 inch Single 1 35 10 256 soft 88 kB 300 FM Model 1/3/4
51⁄4 inch Double 1 40 18 256 180 kB MFM Model 1/3/4P
51⁄4 inch Double 2 40 18 256 360 kB MFM Model 4D
8 inch Double 1 77 26 256 500 kB MFM Model 2
31⁄2 inch Single 1 40 2 1,280 100 kB[28] FM Tandy Portable Disk Drive (aka Brother FB-100, knitking FD-19)
31⁄2 inch Single 1 80 2 1,280 200 kB[29] FM Used only in Tandy Portable Disk Drive 2
51⁄4 inch Double 1 35 18 256 157 kB[30] MFM Color Computer
HP 9114A 31⁄2 inch Double 2 80 16 256 128-710kB[31] 600 MFM Used with HP 110 and Portable Series 40 & 70
HP 9895A 8 inch Double 2 77 29 256 1.18 MB[32] 360 MFM
HP 9130K 51⁄4 inch Double 2 35 16 256 286 kB[33] 300 MFM
Burroughs MD122 8 inch Double 2 139 44 256 soft 6.26 MB[18] 524 MFM
Memorex 650 8 inch single 1 50 8 3,500 b hard 1.4 Mb[15] 375 FM
Memorex 651 single 64 32 1.056 b 2.2 Mb[17]
Platform Size Density Side Track Sector Byte Sectoring Capacity RPM Encoding Note
Commodore 128 (CP/M) 5 1/4 Double 2 40 26 128 Soft 260K 300 MFM Commodore 1571
16 256 320K
9 512 360K
5 1,024 400K

https://www.c64-wiki.com/wiki/Commodore_1571

https://vintagecomputer.ca/files/Commodore/C900/C900%20Floppy%20Specification.pdf

See also

[edit]
  • Zip drive (floppy-like, but incompatible medium using different technology)
  • PocketZip (floppy-like, but incompatible medium using different technology)
  • SuperDisk (floppy-like with drives also compatible with 3.5" floppy disks)
  • Magneto-optical drive (floppy-like, but incompatible medium using different technology)

Notes

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  1. ^ Custom controller with unique track layout.[1]
  2. ^ 16 sector filesystems require a compatible disk controller (PROM update) and Apple DOS 3.3 or later.
  3. ^ Apple II double-density 31⁄2-inch (90 mm) drives use variable sectors sizes (tracks 00-15: 12 sectors, tracks 16-31: 11 sectors, tracks 32-47: 10 sectors, tracks 48-63: 9 sectors, tracks 64-79: 8 sectors), 394 rpm to 590 rpm. [2]
  4. ^ Apple II high-density 31⁄2-inch (90 mm) drives require a compatible disk controller and ProDOS 8.
  5. ^ Third party drives offer up to 1440 KB.
  6. ^ Commodore floppy drives used a fixed rotation speed with variable sector density (see: Zone bit recording).
  7. ^ This format was used by the Amiga 1020 external floppy drive and some third-party drives connected to the normal Amiga floppy drive bus.
  8. ^ a b Though the Amiga used MFM, the format places sectors too close together for a standard IBM PC compatible floppy disk controller to read (appearing as one 5632-byte physical sector per track).
  9. ^ Format used by rare third-party drives with quad density disks; such drives were usually switchable between 80-track and 40-track (A1520/PC-compatible) operation.
  10. ^ Format used by third-party gcrdisk.device driver in order to use PC-standard HD floppy drives (which rotated at a fixed 300 rpm) via the Amiga floppy drive bus. The Amiga's floppy controller could not keep up with the data rate needed for MFM recording on HD floppies without reducing rotational speed, so the third party driver used an alternate GCR mode.
  11. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae The calculated formatted capacity is based on FAT12 format.
  12. ^ While IBM didn't include an 8-inch floppy drive option on any of their PCs and PC DOS, MS-DOS 1.25 supported 8-inch disks and added support for higher capacities in version 2.0. MS-DOS' predecessor 86-DOS used 8-inch diskettes as well.
  13. ^ Rare format appearing on some early PC/XT clones using quad-density disks.
  14. ^ These variations are known as DMF diskettes, used for a time to pack more data on to each disk for software distribution.
  15. ^ a b c d e f Inner 3 tracks of 8 sectors/track format are unused.
  16. ^ The PC98 31⁄2-inch (90 mm) formats are also known as "3 Mode" floppy disks, usable on IBM PC compatibles with a 3-mode floppy drive.
  17. ^ The two sides are managed as two independent 160 KB disks
  18. ^ The two sides are managed as two independent 320 KB disks

References

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  1. ^ US4609949A, Kutaragi, Ken, "Magnetic disc reproducing apparatus", issued 1986-09-02, assigned to Sony Corporation 
  2. ^ a b c d "Model CE-1600F". Sharp PC-1600 Service Manual (PDF). Yamatokoriyama, Japan: Sharp Corporation, Information Systems Group, Quality & Reliability Control Center. July 1986. pp. 98–104. Archived (PDF) from the original on March 23, 2017. Retrieved March 23, 2017.
  3. ^ a b Sharp Service Manual Model CE-140F Pocket Disk Drive (PDF). Sharp Corporation. 00ZCE140F/SME. Archived (PDF) from the original on March 11, 2017. Retrieved March 11, 2017.
  4. ^ Tabor TC-500 Specifications. USA: Tabor Corp. Archived from the original on January 12, 2022.
  5. ^ "PF-10" (PDF). Epson. 1984. Archived from the original (PDF) on June 21, 2020. Retrieved November 30, 2022.
  6. ^ "Floppy Drive Tech Info". www.retrotechnology.com. Retrieved July 6, 2023.
  7. ^ a b NEC μPD72070 - Floppy Disk Controller Specification Version 2.0 (PDF). 2.0 preliminary. NEC Corporation. October 1991. Archived from the original (PDF) on March 20, 2017. Retrieved March 20, 2017.
  8. ^ a b c d "ハードウエア" [Hardware]. NEC PC-88VA (in Japanese). Archived from the original on June 18, 2017.
  9. ^ US4482929A, Beck, John L.; Bornhorst, Randy J. & Smith, Donald J. et al., "Magnetic recording disk cartridge", issued 1984-11-13 
  10. ^ "Fujitsu Sales Prospector 1986". Archive.org. 1986. p. 238. Retrieved November 7, 2023.
  11. ^ "コンピュータ・情報システム・パソコン・周辺機器" [Hitachi Computer Peripherals] (PDF). hitachihyoron.com. January 6, 1985. p. 9. Retrieved November 7, 2023.
  12. ^ Berry, D (September 7, 1982). Lisa Hardware Manual (PDF). Apple Computer Inc. pp. 9–1.
  13. ^ "Fujitsu Sales Prospector 1986". 1986. pp. 238, 239 – via Archive.org.
  14. ^ "FDD-441大容量フロッピーディスク駆動装置の開発" [Development of FDD-441 Large-Capacity Floppy Disk Drive] (PDF). hitachihyoron.com. August 3, 1984. p. 3. Retrieved November 7, 2023.
  15. ^ a b c d 650 Flexible Disc File OEM Manual 2944.010. Memorex Corp. 1972. p. 9.
  16. ^ a b Memorex Markette Flexible Discs (PDF). USA: Memorex Corp. 1978. pp. 1–2.
  17. ^ a b Memorex 651 Flexible Disc File OEM Manual. USA: Memorex Corp. 1977. p. 4.
  18. ^ a b Burroughs MD 122 Brochure. USA: Burroughs Marketing. 1979. p. 2.
  19. ^ "Apple's Twiggy Disks". www.brouhaha.com. Retrieved October 11, 2023.
  20. ^ a b c The IBM Diskette General Information Manual (PDF) (Reference Manual). USA: IBM. 1979. pp. 18–19.
  21. ^ a b c d "Standard Floppy Disk Formats Supported by MS-DOS". 2.0. Microsoft. December 17, 2000. Retrieved February 5, 2020.
  22. ^ a b c d Zbikowski, Mark; Allen, Paul; Ballmer, Steve; Borman, Reuben; Borman, Rob; Butler, John; Carroll, Chuck; Chamberlain, Mark; Chell, David; Colee, Mike; Courtney, Mike; Dryfoos, Mike; Duncan, Rachel; Eckhardt, Kurt; Evans, Eric; Farmer, Rick; Gates, Bill; Geary, Michael; Griffin, Bob; Hogarth, Doug; Johnson, James W.; Kermaani, Kaamel; King, Adrian; Koch, Reed; Landowski, James; Larson, Chris; Lennon, Thomas; Lipkie, Dan; McDonald, Marc; McKinney, Bruce; Martin, Pascal; Mathers, Estelle; Matthews, Bob; Melin, David; Mergentime, Charles; Nevin, Randy; Newell, Dan; Newell, Tani; Norris, David; O'Leary, Mike; O'Rear, Bob; Olsson, Mike; Osterman, Larry; Ostling, Ridge; Pai, Sunil; Paterson, Tim; Perez, Gary; Peters, Chris; Petzold, Charles; Pollock, John; Reynolds, Aaron; Rubin, Darryl; Ryan, Ralph; Schulmeisters, Karl; Shah, Rajen; Shaw, Barry; Short, Anthony; Slivka, Ben; Smirl, Jon; Stillmaker, Betty; Stoddard, John; Tillman, Dennis; Whitten, Greg; Yount, Natalie; Zeck, Steve (1988). "Technical advisors". The MS-DOS Encyclopedia: versions 1.0 through 3.2. By Duncan, Ray; Bostwick, Steve; Burgoyne, Keith; Byers, Robert A.; Hogan, Thom; Kyle, Jim; Letwin, Gordon; Petzold, Charles; Rabinowitz, Chip; Tomlin, Jim; Wilton, Richard; Wolverton, Van; Wong, William; Woodcock, JoAnne (Completely reworked ed.). Redmond, Washington, USA: Microsoft Press. ISBN 1-55615-049-0. LCCN 87-21452. OCLC 16581341. (xix+1570 pages; 26 cm) (NB. This edition was published in 1988 after extensive rework of the withdrawn 1986 first edition by a different team of authors. [3])
  23. ^ a b c d Xerox 16/8 Professional Computer – MS-DOS OS Handbook for 8" Floppy Disks (PDF). Xerox. November 1983.
  24. ^ Hogan, Thom; Iannamico, Mike (1982). Osborne 1 Technical Manual (PDF). Osborne Computer Corporation. p. 39.
  25. ^ "Sega SF-7000 Super Control Station User Guide". Sega Enterprises. Retrieved February 10, 2020.
  26. ^ a b "Victor 9000 Hardware Reference Manual" (PDF). Archived (PDF) from the original on January 29, 2022. Retrieved September 12, 2022.
  27. ^ a b Lemmons, Phil (November 1982). "Victor Victorious". BYTE. p. 216. Retrieved October 19, 2013.
  28. ^ Tandy Portable Disk Drive Operation Manual 26-3808. Japan: Radio Shack. 1985. p. 25.
  29. ^ Tandy Portable Disk Drive 2 Operation Manual 26-3814. Japan: Radio Shack. 1986. p. 33.
  30. ^ Radio Shack Hardware Manual: Color Computer Disk System Owners Manual (1981)(Tandy). 1981.
  31. ^ 9914A Disc Drive (PDF). Hewlett-Packard. June 1, 1984. p. 1-2.
  32. ^ 9895A Flexible Disc Users Manual (PDF). Fort Collins, Colorado USA: Hewlett-Packard Desktop Computer Division. 1978. p. 6.
  33. ^ HP 9130K Flexible Disc Drive Service Documentation (PDF). Fort Collins, Colorado USA: Hewlett-Packard Greeley Division. 1981.
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