Glossary
G-4 Quantum Fireball Plus LM 10.2/15.0/20.5/30.0 GB AT
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GIGABYTE (GB) – One billion bytes (one
thousand megabytes).
GUIDE RAILS – Plastic strips attached to
the sides of a disk drive mounted in an IBM
AT and compatible computers so that the
drive easily slides into place.
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HALF HEIGHT – Term used to describe a
drive that occupies half the vertical space of
the original full size 5 1/4-inch drive. 1.625
inches high.
HARD DISK – A type of storage medium
that retains data as magnetic patterns on a
rigid disk, usually made of an iron oxide or
alloy over a magnesium or aluminum platter.
Because hard disks spin more rapidly than
floppy disks, and the head flies closer to the
disk, hard disks can transfer data faster and
store more in the same volume.
HARD ERROR – A repeatable error in disk
data that persists when the disk is reread,
usually caused by defects in the media
surface.
HEAD – The tiny electromagnetic coil and
metal pole piece used to create and read back
the magnetic patterns (write and read
information) on the media.
HIGH-CAPACITY DRIVE – By industry
conventions typically a drive of 1 gigabytes
or more.
HIGH-LEVEL FORMATTING –
Formatting performed by the operating
system’s format program. Among other
things, the formatting program creates the
root directory and file allocation tables. See
also low-level formatting.
HOME – Reference position track for
recalibration of the actuator, usually the
outer track (track 0).
HOST ADAPTER – A plug-in board that
forms the interface between a particular type
of computer system bus and the disk drive.
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INITIALIZE – See low level formatting.
INITIATOR – A SCSI device that requests
another SCSI device to perform an
operation. A common example of this is a
system requesting data from a drive. The
system is the initiator and the drive is the
target.
INTERFACE – A hardware or software
protocol, contained in the electronics of the
disk controller and disk drive, that manages
the exchange of data between the drive and
computer.
INTERLEAVE – The arrangement of sectors
on a track. A 1:1 interleave arranges the
sectors so that the next sector arrives at the
read/write heads just as the computer is
ready to access it. See also interleave factor.
INTERLEAVE FACTOR – The number of
sectors that pass beneath the read/write
heads before the next numbered sector
arrives. When the interleave factor is 3:1, a
sector is read, two pass by, and then the next
is read. It would take three revolutions of the
disk to access a full track of data. Quantum
drives have an interleave of 1:1, so a full
track of data can be accessed within one
revolution of the disk, thus offering the
highest data throughput possible.
INTERNAL DRIVE – A drive mounted
inside one of a computer’s drive bays (or a
hard disk on a card, which is installed in one
of the computer’s slots).
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JUMPER – A tiny box that slips over two
pins that protrude from a circuit board.
When in place, the jumper connects the pins
electrically. Some board manufacturers use
Dual In-Line Package (DIP) switches
instead of jumpers.