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.
29296 US 19 North, Clearwater.FL 33761
727-772-7455
Used with the permission of Quantum Corp.
