General Introduction

Fdutils is a collection of utilities for configuring and using the Linux floppy driver. With fdutils, you can:

1. Format disks with a higher capacity than usual (up to 1992KB on a 3 1/2 HD disk).
2. Reconfigure the autodetection sequence to automatically detect some of these extended formats.
3. Access various internal driver structures and drive configuration using the floppycontrol program.

This manual describes these utilities, and also the floppy driver itself.

1. Where to get fdutils and its documentation

Fdutils can be found at the following places (+ mirrors):

ftp://www.tux.org/pub/knaff/fdutils/fdutils-5.5.tar.gz
ftp://metalab.unc.edu/pub/Linux/utils/disk-management/fdutils-5.5.tar.gz
ftp://tsx-11.mit.edu/pub/linux/sources/sbin/fdutils-5.5.tar.gz

The FAQ included in this package is also available separately at:

http://alain.knaff.linux.lu/floppy/FAQ.html
http://www.tux.org/pub/knaff/floppy/FAQ.html

The FAQ at fdutils.linux.lu and www.tux.org is usually more up to date than versions found elsewhere. Thus, if you don’t find an answer in the copy of the FAQ you have, please check this one for more recent info.

Before reporting a bug, make sure that it has not yet been fixed in the Alpha patches which can be found at:

http://fdutils.linux.lu
ftp://www.tux.org/pub/knaff/fdutils

These patches are named fdutils-version-ddmm.taz, where version stands for the base version, dd for the day and mm for the month. Due to a lack of space, I usually leave only the most recent patch.

There is an fdutils mailing list at fdutils @ www.tux.org . Please send all bug reports to this list. You may subscribe to the list by sending a message with ’subscribe fdutils @ www.tux.org’ in its body to majordomo @ www.tux.org . (N.B. Please remove the spaces around the "@" both times. I left them there in order to fool spambots.) Announcements of new fdutils versions will also be sent to the list, in addition to the linux announce newsgroups. The mailing list is archived at http://www.tux.org/hypermail/fdutils/latest

2. Basic usage

This chapter describes basic usage of floppies, and gives a few simple tips for using floppies under Linux.

2.1 How disks are organized

All floppies have two levels of formatting, both of which must be known in order to read them. The first is the binary or sector level format, which is how raw data is stored on the disk. The second is a higher level organization, often called a file system, which allows multiple files to be conveniently stored on the disk.

For example, a typical 1.44MB disk contains a low-level format, with 18 sectors per track, 80 tracks, and two sides (or heads); each sector can hold 512 bytes of data for a total of 1474560 bytes (or 1440 KB). When used under MS-DOS, this floppy would have a small portion of the disk used to keep track of files on the disk (including a bootsector, file allocation tables, directories, etc.).

The floppy driver generally takes care of reading the binary, or low-level format. It can often "guess" the low-level disk geometry needed to read the disk. This is called autodetection (see section How autodetection works). If the driver can’t autodetect the disk (e.g. if it is in an unusual format) you can tell the driver what the geometry is either by using the setfdprm (see section setfdprm) utility or by using a fixed geometry device device (e.g. ‘/dev/fd0H1440’).

Under Linux, many different file systems from many sources can be used. Some of these file systems are interpreted via a utility program (for example mtools for using disks with an MS-DOS file system). Many file systems can alternatively be "mounted" to appear in the UNIX directory structure until subsequently being unmounted; this is usually implemented by having the kernel itself interpret the file system on the disk.

2.2 File systems supported by Linux

The following file systems are supported:

OS/2 HPFS:

read-only support (mount/kernel)

Mac HPFS 1.44MB:

read-only (xhfs utility)

MS-DOS:

read, write, format (mtools utility and mount/kernel)

tar, cpio:

compatible with many variations of UNIX (tar, cpio utilities)

System V, minix, xia, ext, ext2:

(mount/kernel)

pure binary disk access:

no file system (any program, usually dd, cat, and cp)

2.3 What’s in a name

The following figure shows the meaning of the different parts of the name of a floppy device:

 +--------------- /dev: directory for devices
 |   +------------- fd: floppy disk device prefix
 |   | +------------ 0: floppy drive #0 (A:) (0-1 typical, 0-7
 |   | |                possible)
 |   | |+-- 3.5" drive: (use d for 5.25" double density drives, and
 |   | ||                    h for 5.25" high density drives,
 |   | ||                    u for 3.5" drive of any density)
 |   | ||   +---- 1440: Capacity (in KB) of format (usually between
 |   | ||   |           360 and 3920)
/dev/fd0u1440

2.4 What to do if you get an unidentified floppy disk

dd if=/dev/fd0 of=/tmp/foo count=1
        # If it works:
getfdprm                # This will report what geometry the disk has
file /tmp/foo           # This may indicate the type of file system
mdir a:                 # Check for an MS-DOS file system
tar tvf /dev/fd0        # Check for a tar archive
cpio -itv < /dev/fd0    # Check for a cpio archive
e2fsck /dev/fd0         # Check for an "ext2" file system
        # If it doesn't work:
        # Try the above dd command using various /dev/fd0* devices

2.5 Nickel tours

2.5.1 mtools

mdir a:                # Read directory of MS-DOS disk in drive A:
mcopy /tmp/foo\* a:    # Copy files beginning with foo in /tmp to A:
mcopy a:\* .           # Copy all files from A: to current directory
mformat a:             # Add MS-DOS file system to formatted disk

2.5.2 Tar (Tape ARchive)

tar tvf /dev/fd0              # Read directory of tar archive in
                              # drive A:
tar cvf /dev/fd0 foo1 foo2    # Write foo1 and foo2 to A: in tar
                              # format foo1/foo2 can be entire
                              # directory trees
tar xvfp /dev/fd0             # extract entire tar archive in
                              # drive A:

Tar is not a file system. Only low-level format (superformat, see section superformat) are needed to prepare a disk to accept a tar archive.

2.5.3 CPIO (CoPy In/Out)

cpio -itv < /dev/fd0        # Read directory of cpio archive in A:
find foo1 foo2 -print | cpio -ov < /dev/fd0
                            # Write foo1/foo2 to A:
                            # foo1/foo2 can be entire directory trees
cpio -idumv < /dev/fd0      # extract entire CPIO archive in drive A:

Note: blocks reported are in 512-byte units (due to UNIX System V heritage). Cpio is not a file system. Only low-level format (fdformat or superformat (see section superformat) needed.

2.6 Ext2 (Second Extended File System)

mke2fs /dev/fd0 1440          # Makes an ext2 filesystem of 1440
                              # block on A:
mke2fs -c /dev/fd0 1440       # Same as above, but tests floppy first
e2fsck /dev/fd0               # Tests filesystem integrity. (like
                              # chkdsk in Dos)
e2fsck -p /dev/fd0            # Repairs filesystem. (like chkdsk /f
                              # in Dos)
mount -t ext2 /dev/fd0 /mnt   # Mounts the disk in A: on /mnt.
                              # The directory /mnt must already exist
umount /mnt                   # Unmounts /mnt. No process should
                              # have its working directory in /mnt
                              # No process should have open files in
                              # /mnt

Note: don’t use ext2 on 2m disks On some systems mke2fs is also called mkfs.ext2, and e2fsck is also called fsck.ext2

2.7 New Features of 1.2+ kernels

2.7.1 New features of 1.2+ kernels

• Faster and more comprehensive automatic sensing of floppy formats
• Second Floppy Disk Controller (FDC) supported
• DOS fdformat-style formats (up to 21 sectors on HD 3.5" disk)
• DOS 2m-style formats (up to 24 sectors equivalent on HD 3.5" disk)
• non-DOS 2m-inspired formats
• Several long-standing bugs fixed
• More exact detection of FDC type
• More exact detection of floppy drives

2.7.2 New features of mtools-3.0

• Support for new floppy formats (fdformat, 2m, 2m-like, ED)
• 2.88MB (Extra Density) floppies supported
• More friendly syntax (e.g. "mcopy a:", "mmove")
• Improved mmount
• 16-bit FATs (needed for some ED formats)
• Automatically sets disk geometry for Linux
• Several bug fixes

NOTE: Mtools has no longer maintained by its original maintainer Emmet P. Gray after 2.0.7.

2.7.3 New Utilities

• superformat (replaces fdformat; up to 3.84 MB floppies, faster, calls mformat)
• new getfdprm/setfdprm
• fdrawcmd (allows user-mode programs to do low-level floppy actions) floppycontrol (general-purpose floppy driver configuration utility)
• MAKEFLOPPIES (makes floppy devices)

3. Device numbers

The floppy device nodes are usually made using the MAKEFLOPPIES shell script (See section makefloppies.).

The major device number for the floppy drives is 2. The minor device number contains describes which drive it represents, and may in addition describe the kind of media which is currently in the drive.

There are two kind of floppy devices:

• Variable geometry device nodes. Their minor number doesn’t depend on the media in the drive, and is calculated as follows:

  minor_device = 128 * fdc_nr + unit_nr

• Fixed geometry device nodes. Their minor number not only depends on the drive which they represent, but also the type of media currently in the drive. It is computed as follows:

  minor_device = 128 * fdc_nr + unit_nr + 4 * format_nr

In this formula, fdc_nr is the number of the floppy disk controller (0 or 1, usually 0), and unit_nr is the Unit number (0 to 3, 0 for Dos drive A:, and 1 for Dos drive B:). Format_nr is only meaningful for the fixed format devices. It describes the disk geometry that is used. It is an index into the geometry list The geometry list. Using all available controller numbers and all available drive numbers, you may thus connect up to 8 floppy drives to a single Linux box.

3.1 Variable format devices

Variable format devices don’t have an intrinsic geometry. When using these devices, the geometry has to be set either by using autodetection (see section How autodetection works), or by using the FDSETPRM or FDGETPRM ioctl. The latter ioctl can be issued using the setfdprm (see section setfdprm) and getfdrpm (see section getfdprm) programs. With the default settings, common formats are detected transparently, and you can access any disk transparently using the variable format devices.

The geometry information is kept as long as the disk is in the drive, and is discarded as soon as the disk is removed, unless the geometry has been declared permanent by using setfdprm’s -p flag (see section setfdprm).

3.2 Fixed format devices

Fixed format devices should not be used under normal circumstances.

Fixed format devices have an intrinsic geometry. They are useful for the fdformat program (which is now considered obsolete), and for booting off floppies which have formats that are different from the default format (because during booting, there is no application that can issue the otherwise needed FDSETPRM ioctl).

3.3 The geometry list

The floppy driver contains a builtin list of 32 formats. This list is used for two purposes:

• It says which geometry is used for the fixed format devices.
• It is used for autodetection

The following formats (geometries) are known:

format_nr

Format

0

autodetect

1

360KB, 5.25" DD drive

2

1200KB, 5.25" HD drive

3

360KB, 3.5" DD drive

4

720KB, 3.5" DD drive

5

360KB, 5.25" DD disk in HD drive

6

720KB, 5.25" DD disk in HD drive

7

1440KB, 3.5" HD drive

8

2880KB, 3.5" ED drive

9

3120KB, 3.5" ED drive

10

1440KB, 5.25" HD drive

11

1680KB, 3.5" HD drive

12

410KB, 5.25" DD disk in HD drive

13

820KB, 3.5" DD drive

14

1476KB, 5.25" HD drive

15

1722KB, 3.5" HD drive

16

420KB, 5.25" DD disk in HD drive

17

830KB, 3.5" DD drive

18

1494KB, 5.25" HD drive

19

1743KB, 3.5" HD drive

20

880KB, 5.25" DD drive

21

1040KB, 3.5" DD drive

22

1120KB, 3.5" DD drive

23

1600KB, 5.25" HD drive

24

1760KB, 3.5" HD drive

25

1920KB, 3.5" HD drive

26

3200KB, 3.5" ED drive

27

3520KB, 3.5" ED drive

28

3840KB, 3.5" ED drive

29

1840KB, 3.5" HD drive

30

800KB, 3.5" DD drive

31

1600KB, 3.5" HD drive

This table lists first the format_nr (0-31) used to compute the minor number, then the capacity of the format (360KB - 3200KB), and then the type of the drive in which this format is used.

The formats 0..8 are the standard PC formats. The remaining formats are extended capacity formats. Some of them have been taken from Heiko Schroeder’s fdpatches (after correcting some minor bugs). Others have been added by David Niemi and me (Alain Knaff). Formats 9, 12, 13, 16, 17, 30 and 31 are non-interleaved formats with normal sized sectors, and have the highest capacity that can be achieved without resorting to interleaving or bigger sectors (More sectors per cylinder). Formats 10, 11, 14, 15, 18, 19 use interleaving interleaving to achieve a higher capacity (Using interleave). Formats 20 and 22 to 29 use bigger sectors than usual (Larger sectors and Mixed sector size (MSS) formats).

In addition to these techniques, formats 13-19 use more cylinders than usual (More Cylinders). USE THESE FORMATS (13-19) ONLY IF YOUR DRIVE SUPPORTS THE NECESSARY NUMBER OF TRACKS

3.4 Adding new formats

You can redefine the default formats using the setfdprm program (setfdprm) (1). The following example illustrates how to add a new 19 sector format, and make a device entry for it. First, we pick an entry for it, which we want to reuse. I recommend to redefine an entry which is only rarely used. For instance, if you have no 5 1/4 drive on your system, you can redefine any 5 1/4 entry without a loss. In our example, we pick 10.

First we make the device node:

mknod /dev/fd0H1520 b 2 40
         ^          ^ ^  ^
         |          | |  Minor device number (format number * 4 +
         |          | |                       drive + controller*128)
         |          | Major device number (always 2!)           
         |          Blockdevice
    A name that you choose for the format. I
    recommend to base the name on the capacity,
    but you may choose any name you want.

Then we redefine the geometry of the new device:

setfdprm /dev/fd0H1520 1520 19 2 80 0 0x1b 0 0xcf 0x6c

NB: This redefines the geometry for any device node with the same format number, not just the new node.

The new geometry is only valid until the next reboot (or removal of the floppy module). In order to make it permanent, you have to execute the setfdprm command from your ‘/etc/rc’ file or whenever you insert the floppy module.

4. Media description

4.1 Introduction

Fdutils-5.0 introduces a new uniform format description, which is supported both by setfdprm and superformat. The new format description is easier to handle, because it allows to set the different parameters of a format description in a symbolic and position independent way, using a series of variable=value clauses. Moreover, it automatically fills in sensible default values for unspecified parameters. Thus you only need to describe those aspects of the format that are important to you, and let the system handle the others.

Moreover, the new description separates those aspects that were specific to the drive (like for instance its rotation speed) from those that are specific to the media (spacial density, number of sectors, etc.).

The same description can be used both by setfdprm and superformat:

setfdprm /dev/fd0 hd sect=21 cyl=83
superformat /dev/fd0 hd sect=21 cyl=83

The first line above configures a 21 sector/83 cylinder format for drive 0, and the second line formats a disk using this same format.

4.2 Syntax

A media description is a series of variable=value and selector clauses. Value is a number followed by an optional unit. The unit is either KB (1024 bytes) or b (blocks of 512 bytes), or none (bytes).

4.2.1 Selecting the density

To select a density just insert its two letter code into the format description. Selecting a density also selects its default number of sectors, heads and cylinders. However, these latter parameters can be overridden.

hd

High density (1440KB for 3 1/2 and 1200KB for 5 1/4). The most commonly used format today.

dd

Double density (720KB for 3 1/2 and 360KB for 5 1/4)

ed

Extra density (2880KB for 3 1/2)

qd

Quad density (720KB for 5 1/4).

sd

Single density (no nominal size). Used mostly for CP/M. Only for experienced users.

If no density is given, the maximal density supported by the drive is used. However, in order to keep the drive description and the media description independent, I strongly suggest that you always indicate the density anyways.

4.2.2 Selecting the number of cylinders, heads and sectors

This subsection describes how to select custom formats with a non-standard number of heads, cylinders or sectors. However, note that just describing the number of sectors, heads and cylinders is not enough: you also need to indicate which density your custom format is based on (cf. previous section).

sect=nb_of_sectors

This describes the number of sectors.

head=nb_of_heads

This describes the number of heads to be used.

cyl=nb_of_cylinders

This described the number of cylinders to be used.

4.2.3 Selecting non-standard sector sizes

In order to achieve a higher capacity, you may want to use a bigger sector size.

ssize=sector_size

Choses a bigger sector size. The sector size is expressed in bytes. Only powers of two between 128 and 32768 are acceptable

sect=nb_of_sectors

Describes the number of sectors. For example hd sect=11 ssize=1024 describes a format where one track (1 side) is made up of 11 sectors of 1024 bytes each (thus 11KB per track, and 22KB per cylinder).

tracksize=size_of_one_track

Describes the size of one track. For example, hd tracksize=11KB ssize=1KB describes a format where one track contains 11KB of data (tracksize) stored in sectors of 1KB each.

This option exists mainly to describe MSS (mixed sector size) formats. For example, hd tracksize=12KB mss describes a format where one track which contains 12 KB of data. The sectors size are chosen by the system in a way to take up the least raw space: 8KB + 4KB.

mss

This option says that the format is an MSS format.

2m

This option says that the format is a so-called 2M format. These formats are intended for easy readability on DOS boxes. Their first track has the usual 18 sectors, whereas the other tracks have bigger sector, and in some cases mixed sector sizes.

4.2.4 Legacy formats

The swapsides format allows to describe disks whose sides are swapped, such as CBM1581 disks.

4.2.5 Expert options

The following options are not needed in most common situations, as they are implied by the density selector. They may be needed to read some legacy (CP/M) formats.

tpi=48

For 5 1/4 disks only. This says that the format uses double-spaced cylinders (implied by double density).

tpi=96

For 5 1/4 disks only. This says that the format uses single-spaced cylinders (implied by quad and high density).

fm=0

Uses MFM encoding (implied by double, quad, high and extra density)

fm=1

Uses FM encoding (implied by single density)

dtr=dtr-code

Sets the data transfer rate. The following table lists the dtr codes for various transfer rates:

dtr-code rate for FM rate for MFM ============================================= 0 250kb/s 500kb/s 1 150kb/s 300kb/s 2 125kb/s 250kb/s 3 500kb/s 1000kb/s

perp=0

Do not use "perpendicular mode" sector headers (this setting is implied by single, double, quad and high density).

perp=1

Use "perpendicular" sector headers (this setting is implied by extra-density)

gap=value

Sets the size of the read/write gap. I don’t know the purpose of this parameter (which is passed as-is to the floppy controller): any value seems to work with any format...

fmt_gap=value

Sets the size of the formatting gap. This is only used by the now obsolete fdformat program, and not by superformat.

4.3 The media description dictionary in /etc/fdmediaprm

‘/usr/local/etc/fdmediaprm’ (2) contains a dictionary of commonly used media descriptions. Each description is identified by a name, which can then be used by setfdprm or superformat to refer to it, instead of an explicit description.

Each definition starts with "name":, followed by the actual description. Definitions may be spread over several lines, for better readability. The file may contain comments, which start with # and stop at the end of the line.

5. Drive descriptions

Unlike earlier version, fdutils-5.0 separates drive descriptions and media description. For more details on this separation, see section Introduction. Drive descriptions are used to describe the hardware characteristics of a drive, such as their maximal density, their rotation speed, their form factor, etc.

5.1 Syntax

A drive description is a series of variable=value and selector clauses.

5.1.1 Density

The density of a drive is the highest media density that it supports. Density is one of sd, dd, qd, hd or ed. Usually, you do not need to specify this parameter, as it can be derived from the drives CMOS code.

5.1.2 Form factor

The form factor of a drive describes the physical dimensions of the media it accepts. It is one of 3.5, 5.25 or etfdprm .3 Selecting non-standard sector sizes

In order to achieve a higher capacity, you may want to use a bigger sector size.