Pliny the Elder

Pliny
On legacy systems, floppy disks are sometimes the only option for media. This page contains helpful tips for Linux and BSD systems for formatting floppy diskettes, as well as a table of commonly-used formats. Almost all computers, including those that run UNIX-like systems as well as DOS/MS-DOS, default to the "IBM PC-Compatibles" formatting standard for floppies. While there are other standards, like those of early Apple / Commodore / etc, they are not of practical use since they are non-standard -- the table below is a summary of the most commonly used "standard" formats.

| Size | Tracks | Sectors | Sides | Formatted Size | Additional Notes | +--------+--------+---------+-------+----------------+-----------------------------------------------------------------+ | 3.5" | 80 | 8/9 | 1 | 320/360kB | Double Density, single sided | +--------+--------+---------+-------+----------------+-----------------------------------------------------------------+ | 3.5" | 80 | 9 | 2 | 720kB | Double Density, double sided | +--------+--------+---------+-------+----------------+-----------------------------------------------------------------+ | 3.5" | 80 | 18 | 1 | 720kB | High Density, single sided | +--------+--------+---------+-------+----------------+-----------------------------------------------------------------+ | 3.5" | 80 | 18 | 2 | 1440kB | "Standard" High Density (HD) capacity | +--------+--------+---------+-------+----------------+-----------------------------------------------------------------+ | 3.5" | 80 | 21 | 2 | 1680kB | Works in most FDDs | +--------+--------+---------+-------+----------------+-----------------------------------------------------------------+ | 3.5" | 82 | 21 | 2 | 1720kB | Highest capacity for most drives, may damage head on old drives | +--------+--------+---------+-------+----------------+-----------------------------------------------------------------+ | 3.5" | 80 | 36 | 2 | 2880kB | Extended Density diskettes - wont work on most drives | +--------+--------+---------+-------+----------------+-----------------------------------------------------------------+ | 5.25" | 40 | 8/9 | 1 | 160/180kB | Original 5.25" standards -- should work in any drive | +--------+--------+---------+-------+----------------+-----------------------------------------------------------------+ | 5.25" | 40 | 8/9 | 2 | 320/360kB | Original 5.25" standards -- should work in any drive | +--------+--------+---------+-------+----------------+-----------------------------------------------------------------+ | 5.25" | 80 | 8 | 2 | 640kB | Quad Density -- fairly standard for later drives | +--------+--------+---------+-------+----------------+-----------------------------------------------------------------+ | 5.25" | 80 | 15 | 2 | 1200kB | Extended density -- probably won't work in many drives | +--------+--------+---------+-------+----------------+-----------------------------------------------------------------+


Linux's GNU userland tools and those traditionally bundled with the BSDs have different ways of setting the settings for the formatting process. While on both systems, running the command to format is `fdformat`, the way they accept setting options varies. In Linux, floppy formatting is set by picking a different device node from the /dev/fd* file tree -- selecting /dev/fd0 results in a standard 1.44MB diskette, while selecting /dev/fd0h1722 makes a 1720kb formatted diskette, for instance. Note: on Linux, a 'd' prefix before the floppy node's size denotes "Double Density", an 'h' denotes "High Density" disks. On *BSD however, there is only one floppy node per physical - /dev/rfd0 in most systems. Parameters for setting number of tracks and sectors per track are done on the command line:
# Make a standard floppy fdformat /dev/rfd0 # Set paramaters manually fdformat -s -c /dev/rfd0 # For example: make a 1720kB disk fdformat -s21 -c82 /dev/rfd0 # You can also set the number of heads (sides) for the disk fdformat -h # Make a 1-sided (720k) HD disk fdformat -s18 -c80 -h1 # On NetBSD, the command substitutes -T for -h: fdformat -S21 -C82 -T1

Pliny

A finally note is that GNU fdformat will format an entire disk, and then verify the disk, whereas *BSD versions format a single cylinder and then verify before moving to the next cylinder. Functionally, they are equivalent.