Maxtor MaxLine Plus II 250GB AT Product Manual page 74

Glossary
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.
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.
MaXLine Plus II 250GB AT
G-8
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.