Maxtor D540X-4G - Manual (Page 49)

Glossary
Maxtor D540X-4G G-3
DISK CONTROLLER – A plug-in board,
or embedded circuitry on the drive, that
passes information to and from the disk. The
Maxtor disk drives all have controllers
embedded on the drive printed-circuit board.
DISKWARE – The program instructions
and data stored on the disk for use by a
processor.
DMA – Acronym for direct memory access. A
process by which data moves directly between
a disk drive (or other device) and system
memory without passing through the CPU,
thus allowing the system to continue
processing other tasks while the new data is
being retrieved.
DRIVE – Short form of disk drive.
DRIVE GEOMETRY – The functional
dimensions of a drive in terms of the number
of heads, cylinders, and sectors per track. See
also logical format.
E
ECC – Acronym for error correction code. The
recording of extra verifying information
encoded along with the disk data. The
controller uses the extra information to check
for data errors, and corrects the errors when
possible.
EMBEDDED SERVO – A timing or
location signal placed on the disk’s surface on
the tracks that also store data. These signals
allow the actuator to fine-tune the position of
the read/write heads.
ENCODING – The protocol by which
particular data patterns are changed prior to
being written on the disk surface as a pattern
of On and Off or 1 and 0 signals.
EXTERNAL DRIVE – A drive mounted in
an enclosure separate from the PC or
computer system enclosure, with its own
power supply and fan, and connected to the
system by a cable.F
FAT – Acronym for file allocation table. A data
table stored on the outer edge of a disk that
tells the operating system which sectors are
allocated to each file and in what order.
FCI – Acronym for flux changes per inch. See
also BPI.
FILE SERVER – A computer that provides
network stations with controlled access to
shareable resources. The network operating
system is loaded on the file server, and most
shareable devices (disk subsystems, printers)
are attached to it. The file server controls
system security and monitors
station-to-station communications. A
dedicated file server can be used only as a file
server while it is on the network. A non
dedicated file server can be used
simultaneously as a file server and a
workstation.
FLUX DENSITY – The number of
magnetic field patterns that can be stored in a
given length of disk surface. The number is
usually stated as flux changes per inch (FCI),
with typical values in the thousands.
FLYING HEIGHT – The distance between
the read/write head and the disk surface
caused by a cushion of air that keeps the head
from contacting the media. Smaller flying
heights permit more dense storage of data, but
require more precise mechanical designs.
FORMAT – To write onto the disk surface a
magnetic track pattern that specifies the
locations of the tracks and sectors. This
information must exist on a disk before it can
store any user data. Formatting erases any
previously stored data.
FORMATTED CAPACITY – The
amount of room left to store data on the disk
after the required space has been used to write
sector headers, boundary definitions, and
timing information generated by a format
operation. All Maxtor drive capacities are
expressed in formatted capacity.
FORM FACTOR – The physical outer
dimensions of a device as defined by industry
standard. For example, most Maxtor disk
drives use a 3 1/2-inch form factor.