(^442) PC Hardware: A Beginner’s Guide
I
nputdevicesservetwodistinctpurposesonaPC.First,theyallowtheusertocommand
and control the activities of the PC; second, input devices allow the user to capture
and enter data into the PC. The most important thing to know about an inputdevice is
howtooperateit.TheinputandoutputdevicesofthePCexisttoallowthehumanoperator
and the PC to communicate with one another.
Output devices are adapted to human senses of sight and sound, but input devices
are adapted to gather data from a number of sources. For example, the operator can
manipulate the keys on a keyboard using a combination of sight and touch to enter
text and numeric data. A mouse captures the movement of the user’s hand to point, select,
and execute objects displayed on the PC’s monitor. Scanners convert captured images and
text into computer-readable forms for manipulation by the user. Video capture cards
convert analog video into digital data that can be viewed on the PC. There are also devices
to capture sound as well as devices that capture data so that the PC can control the
temperature in a building. The options for output devices are limited to sight and sound
(so far), but the options for input devices are virtually limitless as more devices are
adapted to capture data in its natural form, such as thermometers, timing devices,
pressure pads, and a wide variety of other types.
Unlike many of the PC’s components, it really isn’t necessary to know all of the technical
parts and operational details of most input devices. In today’s technology, the primary
input devices—the keyboard and mouse—are considered disposable devices. Should
they sto pworking or become broken, it is usually far easier and often less ex pensive to
simply replace them than it is to repair them. However, these input devices and other
nondisposable input devices must be cared for to keep them operating properly.
This chapter does provide some technical details on most of the current classes of
input devices. This is done primarily to acquaint you with the technologies in use and not
to teach you how to dissect and repair internal technical problems with these devices.
Keyboards
The most common input device is the keyboard. The keyboard allows a user to communi-
cate with the PC through keystrokes that represent character data and commands. Virtually
every PC sold has a keyboard included as a part of its standard package. In fact, most
people take their keyboard for granted and rarely even think about it. As long as the keys
work and the user is able to enter data, the keyboard is just fine.
The keyboard, despite its many variations and ergonomic (human engineering)
styles is very much a standardized device. Virtually all keyboards, like the one shown
in Figure 18-1, have a standard keyboard layout, connect to a PC with primarily one
connector, and are for the most part interchangeable between manufacturers.