HP-UX Reference (11i v2 07/12) - 7 Device (Special) Files, 9 General Information, Index (vol 10)

f
floppy(7) floppy(7)
NAME
floppy - direct flexible (floppy) disk access
DESCRIPTION
Flexible disk devices are removable-media disk devices that are typically used to share data with other sys-
tems. Media types are identified by physical size (such as 3.5-inch and 5.25-inch), number of data surfaces
(or sides), and data density. By convention, flexible disk devices are named using the same conventions as
those used for other disk devices (see disk(7)).
Data can be stored on flexible disk media in a variety of logical formats. The capacity of these devices is
generally too small to hold useful HP-UX file systems. Instead, DOS or LIF file systems (see dosif(4) and
lif(4) for a detailed description of these file systems) are commonly used. Data can also be stored in an
archive-utility format. For example,
tar and cpio are commonly used to share data with other HP-UX
systems (see tar(1) and cpio(1)).
Logical volumes are not supported on flexible disks. The floppy disk does not support partitions. Section
zero (0) is the only accessible partition.
In addition to the various logical formats, data can be stored on flexible disk media in a variety of physical
data formats called geometries. The following parameters are used to describe a flexible disk geometry:
heads Number of surfaces (or sides) on the media that contain valid data.
tracks Number of tracks on a single media surface or side (the term cylinders is sometimes
also used). This value does not include spare tracks.
sectors Number of sectors in a single track. The number of sectors that can fit on a track
depends on the bit density (as controlled by transfer rate and media rotation rate) and
the sector size.
sector size Number of bytes in a logical sector. Since all I/O operations must be an integral
number of sectors in length, this parameter also indicates the minimum character-
special file I/O size.
transfer rate Media data rate in Kbits per second. The transfer rate is an indirect means of
representing bit density. Bit density is measured in bits per radian, and is the formal
intra-track data density parameter for standard specification. Transfer rate is gen-
erally used to program flexible media devices and is therefore more appropriate for
this interface. Since the media rotation rate for most flexible disk devices is standard,
conversion between these two representations is straight-forward.
track density Number of tracks per inch. Some low density formats can be supported on high-
density drives by skipping tracks during head stepping.
data encoding
Encoding method used to store data. FM (frequency modulation) and MFM (modified
frequency modulation) are the most common encoding methods; RLL (run length lim-
ited) is a modification of MFM that allows higher densities.
The following table shows some useful flexible disk media geometries (without density information). The
right-most column indicates which
mediainit -f option should be used to format media to the indi-
cated geometry (see mediainit(1)).
44 Hewlett-Packard Company − 1 − HP-UX 11i Version 2: December 2007 Update