PC Hardware A Beginner’s Guide

(^170) PC Hardware: A Beginner’s Guide
V
irtually every PC sold today has at least one hard disk drive installed inside its
system case. At one time, this was also true of floppy disk drives, but PCs with
floppy disk drives are beginning to disappear, giving way to Zip disks, Super
disks, and other forms of removable mass storage.
The hard disk and floppy disk are types ofsecondary storage, with the PC’s RAM pro-
viding its primary storage (see Chapter 7). Whereprimary storagestores data temporarily
while it’s in use, secondary storage holds data, programs, and other digital objects
permanently. In fact, RAM is referred to astemporary storage, and the hard disk and
floppy disk are consideredpermanent storage. The data is not permanent in the sense that
it is etched in stone, but compared to the volatility of RAM, it is far more enduring.
Permanent storage on a disk drive means that the data is still available even after the
primary power source is removed.

Hard Disk Drives

The hard disk is hardly a personal computer invention. The first hard disks, which first

showed u pin the 1950s on mainframe com puters, were 20 inches in diameter and held

only a few megabytes of data. Hard disks were originally called “fixed disks” and

“Winchester drives” and became known as hard disks later to differentiate them from

floppy disks. However, the basic technology used in the earliest hard disks has not

changed all that much over the years, although the size and capacity of the drives has.

Hard Disk Construction

There are many different types and styles of hard disks on the market, all of which have

roughly the same physical components. The differences among the different drive styles

and types are usually in the components—the materials used and the way they are put

together. But essentially one disk drive operates like all others. The major components in

a typical hard disk drive are as follows (see Figure 9-1):

 Disk platters

 Spindle and spindle motor

 Read/write heads

 Head actuators

 Air filter

 Logic board

 Connectors and jumpers

 Bezel

Of this list, only the connectors and jumpers are accessible outside of the enclosure

that houses all of the other components of the disk drive. The metal case and the components