Glossary
G-8
Maxtor Fireball3
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.
T
TERABYTE (TB)
– A unit of measurement
to 1,024 gigabytes (GB), or
1,099,511,627,776 bytes, except when
referring to disk storage capacity. Storage
capacities of one or more terabytes is achieved
by installing multiple hard drive in a RAID
system. 1 TB = 1,000,000,000,000 bytes
when referring to disk storage capacity. See
also gigabyte.
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
Ultra DMA
– (UDMA, or, more accurately,
Ultra DMA/133) is a protocol for transferring
data between a hard disk drive through the
computer's data paths (or bus) to the
computer's random access memory (RAM).
The Ultra DMA/133 protocol transfers data
in burst mode at a rate of 133 MBps
(megabytes per second), twice as fast as the
previous Direct Memory Access (DMA)
interface.