1FD(4) Linux Programmer's Manual FD(4)
2
6 fd - floppy disk device
7
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
11 either mode 0660 (access checking via group membership) or mode 0666
12 (everybody has access). The minor numbers encode the device type,
13 drive number, and controller number. For each device type (that is,
14 combination of density and track count) there is a base minor number.
15 To this base number, add the drive's number on its controller and 128
16 if the drive is on the secondary controller. In the following device
17 tables, n represents the drive number.
18 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. Don't create device entries for those formats
23 to prevent their usage if you are not sure.
24 Drive independent device files which automatically detect the media
26 format and capacity:
27 Name Base minor #
29 ────────────────────
30 fdn 0
31 5.25 inch double density device files:
33 Name Capac. Cyl. Sect. Heads Base minor #
35 ──────────────────────────────────────────────────────────
36 fdnd360 360K 40 9 2 4
37 5.25 inch high density device files:
39 Name Capac. Cyl. Sect. Heads Base minor #
41 ──────────────────────────────────────────────────────────
42 fdnh360 360K 40 9 2 20
43 fdnh410 410K 41 10 2 48
44 fdnh420 420K 42 10 2 64
45 fdnh720 720K 80 9 2 24
46 fdnh880 880K 80 11 2 80
47 fdnh1200 1200K 80 15 2 8
48 fdnh1440 1440K 80 18 2 40
49 fdnh1476 1476K 82 18 2 56
50 fdnh1494 1494K 83 18 2 72
51 fdnh1600 1600K 80 20 2 92
52 3.5 inch double density device files:
54 Name Capac. Cyl. Sect. Heads Base minor #
56 ──────────────────────────────────────────────────────────
57 fdnD360 360K 80 9 1 12
58 fdnD720 720K 80 9 2 16
59 fdnD800 800K 80 10 2 120
60 fdnD1040 1040K 80 13 2 84
61 fdnD1120 1120K 80 14 2 88
62 3.5 inch high density device files:
64 Name Capac. Cyl. Sect. Heads Base minor #
68 ──────────────────────────────────────────────────────────
69 fdnH360 360K 40 9 2 12
70 fdnH720 720K 80 9 2 16
71 fdnH820 820K 82 10 2 52
72 fdnH830 830K 83 10 2 68
73 fdnH1440 1440K 80 18 2 28
74 fdnH1600 1600K 80 20 2 124
75 fdnH1680 1680K 80 21 2 44
76 fdnH1722 1722K 82 21 2 60
77 fdnH1743 1743K 83 21 2 76
78 fdnH1760 1760K 80 22 2 96
79 fdnH1840 1840K 80 23 2 116
80 fdnH1920 1920K 80 24 2 100
81 3.5 inch extra density device files:
83 Name Capac. Cyl. Sect. Heads Base minor #
85 ──────────────────────────────────────────────────────────
86 fdnE2880 2880K 80 36 2 32
87 fdnCompaQ 2880K 80 36 2 36
88 fdnE3200 3200K 80 40 2 104
89 fdnE3520 3520K 80 44 2 108
90 fdnE3840 3840K 80 48 2 112
91
93 fd special files access the floppy disk drives in raw mode. The fol‐
94 lowing ioctl(2) calls are supported by fd devices:
95 FDCLRPRM
97 clears the media information of a drive (geometry of disk in
98 drive).
99 FDSETPRM
101 sets the media information of a drive. The media information
102 will be lost when the media is changed.
103 FDDEFPRM
105 sets the media information of a drive (geometry of disk in
106 drive). The media information will not be lost when the media
107 is changed. This will disable autodetection. In order to reen‐
108 able autodetection, you have to issue an FDCLRPRM.
109 FDGETDRVTYP
111 returns the type of a drive (name parameter). For formats which
112 work in several drive types, FDGETDRVTYP returns a name which is
113 appropriate for the oldest drive type which supports this for‐
114 mat.
115 FDFLUSH
117 invalidates the buffer cache for the given drive.
118 FDSETMAXERRS
120 sets the error thresholds for reporting errors, aborting the
121 operation, recalibrating, resetting, and reading sector by sec‐
122 tor.
123 FDSETMAXERRS
125 gets the current error thresholds.
126 FDGETDRVTYP
128 gets the internal name of the drive.
129 FDWERRORCLR
131 clears the write error statistics.
132 FDWERRORGET
134 reads the write error statistics. These include the total num‐
135 ber of write errors, the location and disk of the first write
136 error, and the location and disk of the last write error. Disks
137 are identified by a generation number which is incremented at
138 (almost) each disk change.
139 FDTWADDLE
141 Switch the drive motor off for a few microseconds. This might
142 be needed in order to access a disk whose sectors are too close
143 together.
144 FDSETDRVPRM
146 sets various drive parameters.
147 FDGETDRVPRM
149 reads these parameters back.
150 FDGETDRVSTAT
152 gets the cached drive state (disk changed, write protected et
153 al.)
154 FDPOLLDRVSTAT
156 polls the drive and return its state.
157 FDGETFDCSTAT
159 gets the floppy controller state.
160 FDRESET
162 resets the floppy controller under certain conditions.
163 FDRAWCMD
165 sends a raw command to the floppy controller.
166 For more precise information, consult also the <linux/fd.h> and
168 <linux/fdreg.h> include files, as well as the manual page for floppy‐
169 control.
170
172 /dev/fd*
173
175 The various formats allow to read and write many types of disks. How‐
176 ever, if a floppy is formatted with a too small inter sector gap, per‐
177 formance may drop, up to needing a few seconds to access an entire
178 track. To prevent this, use interleaved formats. It is not possible
179 to read floppies which are formatted using GCR (group code recording),
180 which is used by Apple II and Macintosh computers (800k disks). Read‐
181 ing floppies which are hard sectored (one hole per sector, with the
182 index hole being a little skewed) is not supported. This used to be
183 common with older 8 inch floppies.
184
186 chown(1), floppycontrol(1), getfdprm(1), mknod(1), superformat(1),
187 mount(8), setfdprm(8)
188
190 This page is part of release 3.25 of the Linux man-pages project. A
191 description of the project, and information about reporting bugs, can
192 be found at http://www.kernel.org/doc/man-pages/.
193Linux 1995-01-29 FD(4)