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 .I 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 l.
  60 Name    Base minor #
  61 _
  62 \fBfd\fP\fIn\fP 0
  63 .TE
  64 .PP
  65 5.25 inch double-density device files:
  66 .TS
  67 lw(1i) l l l l l.
  68 Name    Capac.  Cyl.    Sect.   Heads   Base minor #
  69 _
  70 \fBfd\fP\fIn\fP\fBd360\fP       360K    40      9       2       4
  71 .TE
  72 .PP
  73 5.25 inch high-density device files:
  74 .TS
  75 lw(1i) l l l l l.
  76 Name    Capac.  Cyl.    Sect.   Heads   Base minor #
  77 _
  78 \fBfd\fP\fIn\fP\fBh360\fP       360K    40      9       2       20
  79 \fBfd\fP\fIn\fP\fBh410\fP       410K    41      10      2       48
  80 \fBfd\fP\fIn\fP\fBh420\fP       420K    42      10      2       64
  81 \fBfd\fP\fIn\fP\fBh720\fP       720K    80      9       2       24
  82 \fBfd\fP\fIn\fP\fBh880\fP       880K    80      11      2       80
  83 \fBfd\fP\fIn\fP\fBh1200\fP      1200K   80      15      2       8
  84 \fBfd\fP\fIn\fP\fBh1440\fP      1440K   80      18      2       40
  85 \fBfd\fP\fIn\fP\fBh1476\fP      1476K   82      18      2       56
  86 \fBfd\fP\fIn\fP\fBh1494\fP      1494K   83      18      2       72
  87 \fBfd\fP\fIn\fP\fBh1600\fP      1600K   80      20      2       92
  88 .TE
  89 .PP
  90 3.5 inch double-density device files:
  91 .TS
  92 lw(1i) l l l l l.
  93 Name    Capac.  Cyl.    Sect.   Heads   Base minor #
  94 _
  95 \fBfd\fP\fIn\fP\fBu360\fP       360K    80      9       1       12
  96 \fBfd\fP\fIn\fP\fBu720\fP       720K    80      9       2       16
  97 \fBfd\fP\fIn\fP\fBu800\fP       800K    80      10      2       120
  98 \fBfd\fP\fIn\fP\fBu1040\fP      1040K   80      13      2       84
  99 \fBfd\fP\fIn\fP\fBu1120\fP      1120K   80      14      2       88
 100 .TE
 101 .PP
 102 3.5 inch high-density device files:
 103 .TS
 104 lw(1i) l l l l l.
 105 Name    Capac.  Cyl.    Sect.   Heads   Base minor #
 106 _
 107 \fBfd\fP\fIn\fP\fBu360\fP       360K    40      9       2       12
 108 \fBfd\fP\fIn\fP\fBu720\fP       720K    80      9       2       16
 109 \fBfd\fP\fIn\fP\fBu820\fP       820K    82      10      2       52
 110 \fBfd\fP\fIn\fP\fBu830\fP       830K    83      10      2       68
 111 \fBfd\fP\fIn\fP\fBu1440\fP      1440K   80      18      2       28
 112 \fBfd\fP\fIn\fP\fBu1600\fP      1600K   80      20      2       124
 113 \fBfd\fP\fIn\fP\fBu1680\fP      1680K   80      21      2       44
 114 \fBfd\fP\fIn\fP\fBu1722\fP      1722K   82      21      2       60
 115 \fBfd\fP\fIn\fP\fBu1743\fP      1743K   83      21      2       76
 116 \fBfd\fP\fIn\fP\fBu1760\fP      1760K   80      22      2       96
 117 \fBfd\fP\fIn\fP\fBu1840\fP      1840K   80      23      2       116
 118 \fBfd\fP\fIn\fP\fBu1920\fP      1920K   80      24      2       100
 119 .TE
 120 .PP
 121 3.5 inch extra-density device files:
 122 .TS
 123 lw(1i) l l l l l.
 124 Name    Capac.  Cyl.    Sect.   Heads   Base minor #
 125 _
 126 \fBfd\fP\fIn\fP\fBu2880\fP      2880K   80      36      2       32
 127 \fBfd\fP\fIn\fP\fBCompaQ\fP     2880K   80      36      2       36
 128 \fBfd\fP\fIn\fP\fBu3200\fP      3200K   80      40      2       104
 129 \fBfd\fP\fIn\fP\fBu3520\fP      3520K   80      44      2       108
 130 \fBfd\fP\fIn\fP\fBu3840\fP      3840K   80      48      2       112
 131 .TE
 132 .SH DESCRIPTION
 133 \fBfd\fP special files access the floppy disk drives in raw mode.
 134 The following
 135 .BR ioctl (2)
 136 calls are supported by \fBfd\fP devices:
 137 .IP \fBFDCLRPRM\fP
 138 clears the media information of a drive (geometry of disk in drive).
 139 .IP \fBFDSETPRM\fP
 140 sets the media information of a drive.
 141 The media information will be
 142 lost when the media is changed.
 143 .IP \fBFDDEFPRM\fP
 144 sets the media information of a drive (geometry of disk in drive).
 145 The media information will not be lost when the media is changed.
 146 This will disable autodetection.
 147 In order to reenable autodetection, you
 148 have to issue an \fBFDCLRPRM\fP.
 149 .IP \fBFDGETDRVTYP\fP
 150 returns the type of a drive (name parameter).
 151 For formats which work
 152 in several drive types, \fBFDGETDRVTYP\fP returns a name which is
 153 appropriate for the oldest drive type which supports this format.
 154 .IP \fBFDFLUSH\fP
 155 invalidates the buffer cache for the given drive.
 156 .IP \fBFDSETMAXERRS\fP
 157 sets the error thresholds for reporting errors, aborting the operation,
 158 recalibrating, resetting, and reading sector by sector.
 159 .IP \fBFDSETMAXERRS\fP
 160 gets the current error thresholds.
 161 .IP \fBFDGETDRVTYP\fP
 162 gets the internal name of the drive.
 163 .IP \fBFDWERRORCLR\fP
 164 clears the write error statistics.
 165 .IP \fBFDWERRORGET\fP
 166 reads the write error statistics.
 167 These include the total number of
 168 write errors, the location and disk of the first write error, and the
 169 location and disk of the last write error.
 170 Disks are identified by a
 171 generation number which is incremented at (almost) each disk change.
 172 .IP \fBFDTWADDLE\fP
 173 Switch the drive motor off for a few microseconds.
 174 This might be
 175 needed in order to access a disk whose sectors are too close together.
 176 .IP \fBFDSETDRVPRM\fP
 177 sets various drive parameters.
 178 .IP \fBFDGETDRVPRM\fP
 179 reads these parameters back.
 180 .IP \fBFDGETDRVSTAT\fP
 181 gets the cached drive state (disk changed, write protected et al.)
 182 .IP \fBFDPOLLDRVSTAT\fP
 183 polls the drive and return its state.
 184 .IP \fBFDGETFDCSTAT\fP
 185 gets the floppy controller state.
 186 .IP \fBFDRESET\fP
 187 resets the floppy controller under certain conditions.
 188 .IP \fBFDRAWCMD\fP
 189 sends a raw command to the floppy controller.
 190 .PP
 191 For more precise information, consult also the \fI<linux/fd.h>\fP and
 192 \fI<linux/fdreg.h>\fP include files, as well as the
 193 .BR floppycontrol (1)
 194 manual page.
 195 .SH FILES
 196 /dev/fd*
 197 .SH NOTES
 198 The various formats permit reading and writing many types of disks.
 199 However, if a floppy is formatted with an inter-sector gap that is too small,
 200 performance may drop,
 201 to the point of needing a few seconds to access an entire track.
 202 To prevent this, use interleaved formats.
 203
 204 It is not possible to
 205 read floppies which are formatted using GCR (group code recording),
 206 which is used by Apple II and Macintosh computers (800k disks).
 207
 208 Reading floppies which are hard sectored (one hole per sector, with
 209 the index hole being a little skewed) is not supported.
 210 This used to be common with older 8-inch floppies.
 211 .\" .SH AUTHORS
 212 .\" Alain Knaff (Alain.Knaff@imag.fr), David Niemi
 213 .\" (niemidc@clark.net), Bill Broadhurst (bbroad@netcom.com).
 214 .SH SEE ALSO
 215 .BR chown (1),
 216 .BR floppycontrol (1),
 217 .BR getfdprm (1),
 218 .BR mknod (1),
 219 .BR superformat (1),
 220 .BR mount (8),
 221 .BR setfdprm (8)