Information
storage devices are a driving force behind the digital
revolution. Of these various devices, the hard drive
is perhaps the most common and easily-recognized. But
while many people know what a hard drive is, few really
know how it is constructed or how it operates. A good
way to begin building this knowledge is with a basic
familiarity with the components of a desktop drive.
The "hard drive" gets its name from the part
that actually stores information: a rigid disk called
a platter (a), which is rotated by a spindle
motor (b). To increase storage capacity, most hard
drives feature two or more platters. Information is
written to and read from the platter by a read/write
head, located in the head stack assembly
(c). An actuator arm (d) holds this assembly
in place. In turn, the actuator arm is positioned by
upper and lower magnets, also known as mag plates
(e). The mag plates control the movement of the
actuator arm across the platter surface. This
movement, along with the spinning of the platter, gives
the read/write head access to specific locations on
the platter.
Signals that are read or written by the head are amplified
by the read/write preamplifier (f) which,
along with the actuator coil (g) and the associated
connectors, make up the flex circuit (h). Near
the flex circuit is the airlock (i). When the
drive is powered down, this device locks the read/write
head into the "landing zone," a safe place
on the platter where no information is stored. This
helps prevents data loss.
These components are encased in a base casting assembly
(j) and a cover (k), which are sealed tightly
in a cleanroom environment. This keeps out dust and
other contaminants that can damage or destroy the drive.
Every drive also contains a printed circuit assembly
(PCA) (l). The PCA houses the drive electronics
that allow the hard drive to communicate with the computer,
and allow all of the hard drive components to work in
synch. Among these electronics are a microprocessor
that controls all of the drive functions; interface
electronics, which communicate with the computer's interface
bus; a controller ASIC, which operates all of the controller
hardware for the drive; the read channel, which encodes
and decodes the data; and a motor ASIC, which drives
the motor and actuator coil.
©
1997 Quantum Corporation
500 McCarthy Blvd, Milpitas.CA
95035
408-894-4000
©1997
Data Recovery Labs, Inc.
2045 Lawson Road, Clearwater.FL
33763
727-726-8985
Used with the permission of Quantum Corp.
