Seagate DiamondMax 17 Manual page 60

Glossary
SPINDLE – The center shaft of the disk upon which the
drive's platters are mounted.
SPUTTER – A type of coating process used to apply the
magnetic coating to some high-performance disks. In
sputtering, the disks are placed in a vacuum chamber and the
coating is vaporized and deposited on the disks. The resulting
surface is hard, smooth, and capable of storing data at high
density. Maxtor disk drives use sputtered thin film disks.
STEPPER – A type of motor that moves in discrete
amounts for each input electrical pulse. Stepper motors used
to be widely used for read/write head positioner, since they
can be geared to move the head one track per step. Stepper
motors are not as fast or reliable as the rotary voice coil
actuators which Maxtor disk drives use.
SUBSTRATE – The material the disk platter is made of
beneath the magnetic coating. Hard disks are generally made
of aluminum or magnesium alloy (or glass, for optical disks)
while the substrate of floppies is usually mylar.
SURFACE – The top or bottom side of the platter which
is coated with the magnetic material for recording data. On
some drives one surface may be reserved for positioning
information.
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.
G-6 Maxtor DiamondMax 17 80-160GB Serial ATA Hard Disk Drive
T
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 Maxtor drive is expressed
in formatted capacity.
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. Maxtor's actuator uses voice-coil technology, and
thereby eliminates the high stress wearing parts found on
stepper motor type actuators.
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.