1FD(4)                      Linux Programmer's Manual                     FD(4)
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NAME

6       fd - floppy disk device
7

CONFIGURATION

9       Floppy  drives  are  block devices with major number 2.  Typically they
10       are owned by root:floppy (i.e., user root, group floppy) and  have  ei‐
11       ther mode 0660 (access checking via group membership) or mode 0666 (ev‐
12       erybody has access).  The minor numbers encode the device  type,  drive
13       number, and controller number.  For each device type (that is, combina‐
14       tion of density and track count) there is a base minor number.  To this
15       base  number,  add  the drive's number on its controller and 128 if the
16       drive is on the secondary controller.  In the following device  tables,
17       n represents the drive number.
18
19       Warning:  if  you  use  formats with more tracks than supported by your
20       drive, you may cause it mechanical damage.  Trying once if more  tracks
21       than  the  usual  40/80 are supported should not damage it, but no war‐
22       ranty is given for that.  If you are not sure, don't create device  en‐
23       tries for those formats, so as to prevent their usage.
24
25       Drive-independent  device  files  which  automatically detect the media
26       format and capacity:
27
28       Name    Base
29              minor #
30       ───────────────
31       fdn       0
32
33       5.25 inch double-density device files:
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35       Name         Capacity   Cyl.   Sect.   Heads    Base
36                      KiB                             minor #
37       ───────────────────────────────────────────────────────
38       fdnd360        360       40      9       2        4
39
40       5.25 inch high-density device files:
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42       Name         Capacity   Cyl.   Sect.   Heads    Base
43                      KiB                             minor #
44       ───────────────────────────────────────────────────────
45       fdnh360        360       40      9       2       20
46       fdnh410        410       41     10       2       48
47       fdnh420        420       42     10       2       64
48       fdnh720        720       80      9       2       24
49       fdnh880        880       80     11       2       80
50       fdnh1200       1200      80     15       2        8
51       fdnh1440       1440      80     18       2       40
52       fdnh1476       1476      82     18       2       56
53       fdnh1494       1494      83     18       2       72
54       fdnh1600       1600      80     20       2       92
55
56       3.5 inch double-density device files:
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58       Name         Capacity   Cyl.   Sect.   Heads    Base
59                      KiB                             minor #
60       ───────────────────────────────────────────────────────
61       fdnu360        360       80      9       1       12
62       fdnu720        720       80      9       2       16
63       fdnu800        800       80     10       2       120
64       fdnu1040       1040      80     13       2       84
65       fdnu1120       1120      80     14       2       88
66
67       3.5 inch high-density device files:
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69       Name         Capacity   Cyl.   Sect.   Heads    Base
70                      KiB                             minor #
71       ───────────────────────────────────────────────────────
72       fdnu360        360       40      9       2       12
73       fdnu720        720       80      9       2       16
74       fdnu820        820       82     10       2       52
75       fdnu830        830       83     10       2       68
76       fdnu1440       1440      80     18       2       28
77       fdnu1600       1600      80     20       2       124
78       fdnu1680       1680      80     21       2       44
79       fdnu1722       1722      82     21       2       60
80       fdnu1743       1743      83     21       2       76
81       fdnu1760       1760      80     22       2       96
82       fdnu1840       1840      80     23       2       116
83       fdnu1920       1920      80     24       2       100
84
85       3.5 inch extra-density device files:
86
87       Name         Capacity   Cyl.   Sect.   Heads    Base
88                      KiB                             minor #
89       ───────────────────────────────────────────────────────
90       fdnu2880       2880      80     36       2       32
91       fdnCompaQ      2880      80     36       2       36
92       fdnu3200       3200      80     40       2       104
93       fdnu3520       3520      80     44       2       108
94       fdnu3840       3840      80     48       2       112
95

DESCRIPTION

97       fd special files access the floppy disk drives in raw mode.   The  fol‐
98       lowing ioctl(2) calls are supported by fd devices:
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100       FDCLRPRM
101              clears  the  media  information  of a drive (geometry of disk in
102              drive).
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104       FDSETPRM
105              sets the media information of a drive.   The  media  information
106              will be lost when the media is changed.
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108       FDDEFPRM
109              sets  the  media  information  of  a  drive (geometry of disk in
110              drive).  The media information will not be lost when  the  media
111              is changed.  This will disable autodetection.  In order to reen‐
112              able autodetection, you have to issue an FDCLRPRM.
113
114       FDGETDRVTYP
115              returns the type of a drive (name parameter).  For formats which
116              work in several drive types, FDGETDRVTYP returns a name which is
117              appropriate for the oldest drive type which supports  this  for‐
118              mat.
119
120       FDFLUSH
121              invalidates the buffer cache for the given drive.
122
123       FDSETMAXERRS
124              sets the error thresholds for reporting errors, aborting the op‐
125              eration, recalibrating, resetting, and reading sector by sector.
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127       FDSETMAXERRS
128              gets the current error thresholds.
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130       FDGETDRVTYP
131              gets the internal name of the drive.
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133       FDWERRORCLR
134              clears the write error statistics.
135
136       FDWERRORGET
137              reads the write error statistics.  These include the total  num‐
138              ber  of  write  errors, the location and disk of the first write
139              error, and the location and disk of the last write error.  Disks
140              are  identified  by  a generation number which is incremented at
141              (almost) each disk change.
142
143       FDTWADDLE
144              Switch the drive motor off for a few microseconds.   This  might
145              be  needed in order to access a disk whose sectors are too close
146              together.
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148       FDSETDRVPRM
149              sets various drive parameters.
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151       FDGETDRVPRM
152              reads these parameters back.
153
154       FDGETDRVSTAT
155              gets the cached drive state (disk changed,  write  protected  et
156              al.)
157
158       FDPOLLDRVSTAT
159              polls the drive and return its state.
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161       FDGETFDCSTAT
162              gets the floppy controller state.
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164       FDRESET
165              resets the floppy controller under certain conditions.
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167       FDRAWCMD
168              sends a raw command to the floppy controller.
169
170       For  more  precise  information,  consult  also  the  <linux/fd.h>  and
171       <linux/fdreg.h> include files, as well as the  floppycontrol(1)  manual
172       page.
173

FILES

175       /dev/fd*
176

NOTES

178       The  various  formats  permit  reading and writing many types of disks.
179       However, if a floppy is formatted with an inter-sector gap that is  too
180       small,  performance  may drop, to the point of needing a few seconds to
181       access an entire track.  To prevent this, use interleaved formats.
182
183       It is not possible to read  floppies  which  are  formatted  using  GCR
184       (group code recording), which is used by Apple II and Macintosh comput‐
185       ers (800k disks).
186
187       Reading floppies which are hard sectored (one hole per sector, with the
188       index  hole  being  a little skewed) is not supported.  This used to be
189       common with older 8-inch floppies.
190

SEE ALSO

192       chown(1),  floppycontrol(1),  getfdprm(1),  mknod(1),   superformat(1),
193       mount(8), setfdprm(8)
194

COLOPHON

196       This  page  is  part of release 5.13 of the Linux man-pages project.  A
197       description of the project, information about reporting bugs,  and  the
198       latest     version     of     this    page,    can    be    found    at
199       https://www.kernel.org/doc/man-pages/.
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203Linux                             2020-08-13                             FD(4)
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