Quantum FIREBALL PLUS AS 10.2 Product Manual page 158

Glossary
T T T T
THIN FILM – A type of coating, used for
disk surfaces. Thin film surfaces allow more
bits to be stored per disk.
TPI – Acronym for tracks per inch. The
number of tracks or cylinders that are
written in each inch of travel across the
surface of a disk.
TRACK – One of the many concentric
magnetic circle patterns written on a disk
surface as a guide to where to store and read
the data.
TRACK DENSITY – How closely the tracks
are packed on a disk surface. The number is
specified as tracks per inch (TPI).
TRACK TO TRACK SEEK TIME – The
time required for the read/write heads to
move to an adjacent track.
TRANSFER RATE – The rate at which the
disk sends and receives data from the
controller. Drive specifications usually
reference a high number that is the burst
mode rate for transferring data across the
interface from the disk buffer to system
RAM. Sustained data transfer is at a much
lower rate because of system processing
overhead, head switches, and seeks.
U U U U
UNFORMATTED CAPACITY – The total
number of bytes of data that could be fit onto
a disk. Formatting the disk requires some of
this space to record location, boundary
definitions, and timing information. After
formatting, user data can be stored on the
remaining disk space, known as formatted
capacity. The size of a Quantum drive is
expressed in formatted capacity.
G-8 Quantum Fireball Plus LM 10.2/15.0/20.5/30.0 GB AT
V V V V
VOICE COIL – A type of motor used to
move the disk read/write head in and out to
the right track. Voice-coil actuators work
like loudspeakers with the force of a
magnetic coil causing a proportionate
movement of the head. Quantum's actuator
uses voice-coil technology, and thereby
eliminates the high stress wearing parts
found on stepper motor type actuators.
W W W W
WEDGE SERVO – The position on every
track that contains data used by the closed
loop positioning control. This information is
used to fine tune the position of the
read/write heads exactly over the track
center.
WINCHESTER DISKS – Hard disks that
use a technology similar to an IBM model
using Winchester as the code name. These
disks use read/write heads that ride just
above the magnetic surface, held up by the
air flow created by the turning disk. When
the disk stops turning, the heads land on the
surface, which has a specially lubricated
coating. Winchester disks must be sealed
and have a filtration system since ordinary
dust particles are large enough to catch
between the head and the disk.
WRITE ONCE – In the context of optical
disks, technologies that allow the drive to
store data on a disk and read it back, but not
to erase it.