@node Basic usage, Device numbers, Location, Top
@chapter Basic usage

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

@menu
* Disk organisation   :: How a disk is organized, high-level and low-level
                         formats
* File systems        :: Which file systems does Linux support
* Device names        :: How floppy drives are named
* Identifying disks   :: How to identify a disk
* Nickel tours        :: Short summaries of the various storage methods
* New features        :: New features of the kernel, mtools, and fdutils
@end menu

@node Disk organisation, File systems, Basic usage, Basic usage
@section How disks are organized
@cindex low level format
@cindex format (low level vs. high level)
@cindex high level format

All floppies have two levels of @emph{formatting}, both of which must be
known in order to read them.  The first is the @emph{binary} or
@emph{sector} level format, which is how raw data is stored on the disk.
The second is a higher level organization, often called a @emph{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
(@pxref{Autodetection}).  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 @code{setfdprm} (@pxref{setfdprm})
utility or by using a fixed geometry device device
(e.g. @file{/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 @code{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.

@node File systems, Device names, Disk organisation, Basic usage
@section File systems supported by Linux
@cindex supported file systems
@cindex file systems supported by linux

The following file systems are supported:

@table @strong
@item OS/2 HPFS:
read-only support (mount/kernel)
@item Mac HPFS 1.44MB:
read-only (xhfs utility)
@item MS-DOS:
read, write, format (mtools utility @emph{and} mount/kernel)
@item tar, cpio:
compatible with many variations of UNIX (tar, cpio utilities)
@item System V, minix, xia, ext, ext2:
(mount/kernel)
@item pure binary disk access:
no file system (any program, usually dd, cat, and cp)
@end table

@node Device names, Identifying disks, File systems, Basic usage
@section What's in a name
@cindex floppy device name
@cindex file name of floppy devices
@cindex name of floppy devices

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

@example
 +--------------- /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
@end example


@node Identifying disks, Nickel tours, Device names, Basic usage
@section What to do if you get an unidentified floppy disk
@cindex indentifying unknown disks

@example
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
@end example

@node Nickel tours, New features, Identifying disks, Basic usage
@section Nickel tours
@cindex nickel tours

@menu
* Mtools             :: Access MS-Dos disks from Unix
* Tar                :: Tarring files directly to floppy disks
* CPIO               :: Another archive format
* Ext2               :: Seconded Extended File System
@end menu

@node Mtools, Tar, Nickel tours, Nickel tours
@subsection mtools
@cindex mtools (nickel tour)

@example
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
@end example

@node Tar, CPIO, Mtools, Nickel tours
@subsection Tar (Tape ARchive)
@cindex tar

@example
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:
@end example

Tar is not a file system.  Only low-level format (@code{superformat},
@pxref{superformat}) are needed to prepare a disk to accept a tar
archive.

@node CPIO, Ext2, Tar, Nickel tours
@subsection CPIO (CoPy In/Out)
@cindex CPIO

@example
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:
@end example

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 (@pxref{superformat}) needed.

@node Ext2,, CPIO, Nickel tours
@section Ext2 (Second Extended File System)
@cindex Ext2

@example
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
@end example

Note: don't use ext2 on 2m disks
On some systems @code{mke2fs} is also called mkfs.ext2, and e2fsck is also
called fsck.ext2

@node New features,, Nickel tours, Basic usage
@section New Features of 1.2+ kernels
@cindex New features

@menu
* kernel                 :: New kernel features since 1.2.0
* mtools                 :: New mtools features since mtools-3.0
* fdutils                :: Utilities contained in the fdutils package
@end menu

@node kernel, mtools, New features, New features
@subsection New features of 1.2+ kernels
@cindex Kernel (new features)

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

@node mtools, fdutils, kernel, New features
@subsection New features of mtools-3.0
@cindex Mtools (new features)

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

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

@node fdutils,, mtools, New features
@subsection New Utilities
@cindex Fdutils (brief list of supplied utilities)

@itemize @bullet
@item
@code{superformat} (replaces fdformat; up to 3.84 MB floppies, faster,
calls mformat)

@item
new @code{getfdprm}/@code{setfdprm}

@item
@code{fdrawcmd} (allows user-mode programs to do low-level floppy
actions) @code{floppycontrol} (general-purpose floppy driver
configuration utility)

@item
@code{MAKEFLOPPIES} (makes floppy devices)
@end itemize