man4/fd.4

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   2 .\" Copyright (c) 1993 Michael Haardt (michael@cantor.informatik.rwth-aachen.de)
   3 .\" and 1994,1995 Alain Knaff (Alain.Knaff@imag.fr)
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  26 .\" Modified, Sun Feb 26 15:00:02 1995, faith@cs.unc.edu
  27 .\"
  28 .TH FD 4 2014-05-10 "Linux" "Linux Programmer's Manual"
  29 .SH NAME
  30 fd \- floppy disk device
  31 .SH CONFIGURATION
  32 Floppy drives are block devices with major number 2.
  33 Typically they
  34 are owned by
  35 root:floppy
  36 (i.e., user root, group floppy) and have
  37 either mode 0660 (access checking via group membership) or mode 0666
  38 (everybody has access).
  39 The minor
  40 numbers encode the device type, drive number, and controller number.
  41 For each device type (that is, combination of density and track count)
  42 there is a base minor number.
  43 To this base number, add the drive's
  44 number on its controller and 128 if the drive is on the secondary
  45 controller.
  46 In the following device tables, \fIn\fP represents the
  47 drive number.
  48 .PP
  49 \fBWarning: if you use formats with more tracks
  50 than supported by your drive, you may cause it mechanical damage.\fP
  51 Trying once if more tracks than the usual 40/80 are supported should not
  52 damage it, but no warranty is given for that.
  53 If you are not sure, don't create device
  54 entries for those formats, so as to prevent their usage.
  55 .PP
  56 Drive-independent device files which automatically detect the media
  57 format and capacity:
  58 .TS
  59 l c
  60 l c.
  61 Name    Base
  62         minor #
  63 _
  64 \fBfd\fP\fIn\fP 0
  65 .TE
  66 .PP
  67 5.25 inch double-density device files:
  68 .TS
  69 lw(1i) l l l l c
  70 lw(1i) c c c c c.
  71 Name    Capacity        Cyl.    Sect.   Heads   Base
  72         KiB                             minor #
  73 _
  74 \fBfd\fP\fIn\fP\fBd360\fP       360     40      9       2       4
  75 .TE
  76 .PP
  77 5.25 inch high-density device files:
  78 .TS
  79 lw(1i) l l l l c
  80 lw(1i) c c c c c.
  81 Name    Capacity        Cyl.    Sect.   Heads   Base
  82         KiB                             minor #
  83 _
  84 \fBfd\fP\fIn\fP\fBh360\fP       360     40      9       2       20
  85 \fBfd\fP\fIn\fP\fBh410\fP       410     41      10      2       48
  86 \fBfd\fP\fIn\fP\fBh420\fP       420     42      10      2       64
  87 \fBfd\fP\fIn\fP\fBh720\fP       720     80      9       2       24
  88 \fBfd\fP\fIn\fP\fBh880\fP       880     80      11      2       80
  89 \fBfd\fP\fIn\fP\fBh1200\fP      1200    80      15      2       8
  90 \fBfd\fP\fIn\fP\fBh1440\fP      1440    80      18      2       40
  91 \fBfd\fP\fIn\fP\fBh1476\fP      1476    82      18      2       56
  92 \fBfd\fP\fIn\fP\fBh1494\fP      1494    83      18      2       72
  93 \fBfd\fP\fIn\fP\fBh1600\fP      1600    80      20      2       92
  94 .TE
  95 .PP
  96 3.5 inch double-density device files:
  97 .TS
  98 lw(1i) l l l l c
  99 lw(1i) c c c c c.
 100 Name    Capacity        Cyl.    Sect.   Heads   Base
 101         KiB                             minor #
 102 _
 103 \fBfd\fP\fIn\fP\fBu360\fP       360     80      9       1       12
 104 \fBfd\fP\fIn\fP\fBu720\fP       720     80      9       2       16
 105 \fBfd\fP\fIn\fP\fBu800\fP       800     80      10      2       120
 106 \fBfd\fP\fIn\fP\fBu1040\fP      1040    80      13      2       84
 107 \fBfd\fP\fIn\fP\fBu1120\fP      1120    80      14      2       88
 108 .TE
 109 .PP
 110 3.5 inch high-density device files:
 111 .TS
 112 lw(1i) l l l l c
 113 lw(1i) c c c c c.
 114 Name    Capacity        Cyl.    Sect.   Heads   Base
 115         KiB                             minor #
 116 _
 117 \fBfd\fP\fIn\fP\fBu360\fP       360     40      9       2       12
 118 \fBfd\fP\fIn\fP\fBu720\fP       720     80      9       2       16
 119 \fBfd\fP\fIn\fP\fBu820\fP       820     82      10      2       52
 120 \fBfd\fP\fIn\fP\fBu830\fP       830     83      10      2       68
 121 \fBfd\fP\fIn\fP\fBu1440\fP      1440    80      18      2       28
 122 \fBfd\fP\fIn\fP\fBu1600\fP      1600    80      20      2       124
 123 \fBfd\fP\fIn\fP\fBu1680\fP      1680    80      21      2       44
 124 \fBfd\fP\fIn\fP\fBu1722\fP      1722    82      21      2       60
 125 \fBfd\fP\fIn\fP\fBu1743\fP      1743    83      21      2       76
 126 \fBfd\fP\fIn\fP\fBu1760\fP      1760    80      22      2       96
 127 \fBfd\fP\fIn\fP\fBu1840\fP      1840    80      23      2       116
 128 \fBfd\fP\fIn\fP\fBu1920\fP      1920    80      24      2       100
 129 .TE
 130 .PP
 131 3.5 inch extra-density device files:
 132 .TS
 133 lw(1i) l l l l c
 134 lw(1i) c c c c c.
 135 Name    Capacity        Cyl.    Sect.   Heads   Base
 136         KiB                             minor #
 137 _
 138 \fBfd\fP\fIn\fP\fBu2880\fP      2880    80      36      2       32
 139 \fBfd\fP\fIn\fP\fBCompaQ\fP     2880    80      36      2       36
 140 \fBfd\fP\fIn\fP\fBu3200\fP      3200    80      40      2       104
 141 \fBfd\fP\fIn\fP\fBu3520\fP      3520    80      44      2       108
 142 \fBfd\fP\fIn\fP\fBu3840\fP      3840    80      48      2       112
 143 .TE
 144 .SH DESCRIPTION
 145 \fBfd\fP special files access the floppy disk drives in raw mode.
 146 The following
 147 .BR ioctl (2)
 148 calls are supported by \fBfd\fP devices:
 149 .IP \fBFDCLRPRM\fP
 150 clears the media information of a drive (geometry of disk in drive).
 151 .IP \fBFDSETPRM\fP
 152 sets the media information of a drive.
 153 The media information will be
 154 lost when the media is changed.
 155 .IP \fBFDDEFPRM\fP
 156 sets the media information of a drive (geometry of disk in drive).
 157 The media information will not be lost when the media is changed.
 158 This will disable autodetection.
 159 In order to reenable autodetection, you
 160 have to issue an \fBFDCLRPRM\fP.
 161 .IP \fBFDGETDRVTYP\fP
 162 returns the type of a drive (name parameter).
 163 For formats which work
 164 in several drive types, \fBFDGETDRVTYP\fP returns a name which is
 165 appropriate for the oldest drive type which supports this format.
 166 .IP \fBFDFLUSH\fP
 167 invalidates the buffer cache for the given drive.
 168 .IP \fBFDSETMAXERRS\fP
 169 sets the error thresholds for reporting errors, aborting the operation,
 170 recalibrating, resetting, and reading sector by sector.
 171 .IP \fBFDSETMAXERRS\fP
 172 gets the current error thresholds.
 173 .IP \fBFDGETDRVTYP\fP
 174 gets the internal name of the drive.
 175 .IP \fBFDWERRORCLR\fP
 176 clears the write error statistics.
 177 .IP \fBFDWERRORGET\fP
 178 reads the write error statistics.
 179 These include the total number of
 180 write errors, the location and disk of the first write error, and the
 181 location and disk of the last write error.
 182 Disks are identified by a
 183 generation number which is incremented at (almost) each disk change.
 184 .IP \fBFDTWADDLE\fP
 185 Switch the drive motor off for a few microseconds.
 186 This might be
 187 needed in order to access a disk whose sectors are too close together.
 188 .IP \fBFDSETDRVPRM\fP
 189 sets various drive parameters.
 190 .IP \fBFDGETDRVPRM\fP
 191 reads these parameters back.
 192 .IP \fBFDGETDRVSTAT\fP
 193 gets the cached drive state (disk changed, write protected et al.)
 194 .IP \fBFDPOLLDRVSTAT\fP
 195 polls the drive and return its state.
 196 .IP \fBFDGETFDCSTAT\fP
 197 gets the floppy controller state.
 198 .IP \fBFDRESET\fP
 199 resets the floppy controller under certain conditions.
 200 .IP \fBFDRAWCMD\fP
 201 sends a raw command to the floppy controller.
 202 .PP
 203 For more precise information, consult also the \fI<linux/fd.h>\fP and
 204 \fI<linux/fdreg.h>\fP include files, as well as the
 205 .BR floppycontrol (1)
 206 manual page.
 207 .SH FILES
 208 .I /dev/fd*
 209 .SH NOTES
 210 The various formats permit reading and writing many types of disks.
 211 However, if a floppy is formatted with an inter-sector gap that is too small,
 212 performance may drop,
 213 to the point of needing a few seconds to access an entire track.
 214 To prevent this, use interleaved formats.
 215 .PP
 216 It is not possible to
 217 read floppies which are formatted using GCR (group code recording),
 218 which is used by Apple II and Macintosh computers (800k disks).
 219 .PP
 220 Reading floppies which are hard sectored (one hole per sector, with
 221 the index hole being a little skewed) is not supported.
 222 This used to be common with older 8-inch floppies.
 223 .\" .SH AUTHORS
 224 .\" Alain Knaff (Alain.Knaff@imag.fr), David Niemi
 225 .\" (niemidc@clark.net), Bill Broadhurst (bbroad@netcom.com).
 226 .SH SEE ALSO
 227 .BR chown (1),
 228 .BR floppycontrol (1),
 229 .BR getfdprm (1),
 230 .BR mknod (1),
 231 .BR superformat (1),
 232 .BR mount (8),
 233 .BR setfdprm (8)