Maxtor DIAMONDMAX 91536H2 - Manual (Page 58)

GLOSSARY
GL – 1
GLOSSARY
Glossary
A
ACCESS
To obtain data from, or place data into, RAM, a register, or data
storage device.
ACCESS TIME
The interval between the issuing of an access command and the
instant that the target data may be read or written. Access time
includes seek time, latency and controller overhead time.
ADDRESS
A number, generally binary, distinguishing a specific member of an
ordered set of locations. In disk engineering, the address may
consist of drives (unit address), radial positions (cylinder address),
or circumferential position (sector address).
ALLOCATION
A process of assigning designated areas of the disk to particular
files.
ALTERNATE TRACK
A spare track used in the event that a normal track becomes
damaged or is unusable.
ANALOG
A signal or system that does not use digital states to convey
information. A signal may have any number of significant states
(values), contrasted to digital signals which can only have two
states.
ANSI
American National Standards Institute.
APPLICATION PROGRAM
A sequence of programmed instructions that tell the computer how
to perform some end-user task, such as accounting or word
processing.
AREAL DENSITY
Bit density (bits per inch) multiplied by track density (tracks per inch)
or bits per square inch.
ASYMMETRY
A distortion of the readback signal which is shown in different
intervals between the positive and negative voltage peaks.
AUXILIARY MEMORY
Memory other than main memory; generally a mass-storage
subsystem containing disk drives and backup tape drives,
controller(s) and buffer memory (also called peripheral memory).
AVERAGE ACCESS TIME
The average time to make all possible length accesses (seeks).
AVERAGE SEEK TIME
The average time to make all possible length seeks. A typical
measure of performance.
B
BAD BLOCK
A block that cannot store data because of a media flaw.
BIT
An abbreviation for binary digit, of which there are two (0 and 1). A
bit is the basic data unit of most digital computers. A bit is usually
part of a data byte or word, but bits may be used singly to control or
read logic “on-off” functions. The fundamental unit information,
often used loosely to refer to a circuit or magnetization state at a
particular instant in time.
BIOS
Acronym for Basic Input/Output System. The firmware area of a CPU
that controls operations through the system bus and to the
attached cards and peripheral devices.
BPI
Acronym for bits per inch. See bit density.
BLOCK
A group of bytes handled, stored, and accessed as a logical data
unit, such as an individual file record.
BUFFER
A temporary data storage area that compensates for a difference in
data transfer rates and/or data processing rates between sender
and receiver.
BUS
A collection of functionally parallel conductors that forms an
interconnection between functional blocks in a digital device. A
length of parallel conductors that forms a major interconnection
route between the computer system CPU (central processing unit)
and its peripheral subsystems. Depending on its design, a bus may
carry data, addresses, power, and more.
BYTE
An ordered collection of bits treated as a unit. Most often, a byte is
understood to consist of eight bits. One byte is necessary to define
an alphanumeric character.
C
CACHE
Random access memory (RAM) used as a buffer between the CPU
and the disk drive.
CAPACITY
The amount of data, usually expressed in bytes, which can be stored
in a given device or portion of same.
CENTRAL PROCESSING UNIT (CPU)
The heart of the computer system that executes programmed
instructions. It includes the arithmetic logic unit (ALU) for performing
all math and logic operations, a control section for interpreting and
executing instructions, internal memory for temporary storage of
program variables and other functions.
CHANNEL
A collection of electronic circuits used in the process of writing and
reading information to and from magnetic media.
CHARACTER
An ordered collection of bits representing one of a set of
predefined symbols. Often the term is used interchangeably with
byte, but this is inexact.
CLOSED LOOP
A control technique that enables the positioning system to correct
off-track errors in real time. The actual head position is monitored
and compared to the ideal track position to determine any position
error that might be occurring. This information is then used to
produce a correction signal (feedback) that goes to the positioner
to correct the error. (See also track following servo).
CLOSED LOOP SERVO
A servo control technique that uses position feedback to correct
off-track errors. See Track Following Servo.
CLUSTER
The smallest allocatable unit of disk storage allowed by MS-DOS;
each FAT entry represents one cluster.
CONTROLLER
An electronic device for connecting one or more mass storage
peripherals (rigid disk drives, tape drives, and optical disk drives) to
the input/output circuits of a host computer. Controllers vary in
complexity, with more sophisticated units able to buffer and
schedule commands, correct data errors, and bypass media defects
without host intervention.