Microsoft Office Tutorials and References
In Depth Information
Understanding Assistive Devices
People with physical impairments or disabilities can use computers because of advances
in making computers accessible to everyone. For example, people who cannot use their
arms or hands instead can use foot, head, or eye movements to control the pointer.
People with poor vision can use keyboards with large keys for input, screen enlargers to
enlarge the type and images on the monitor, or screen readers to read the content of the
screen aloud. Computers have even been developed that can be controlled by a person’s
thoughts, that is, the brain’s electromagnetic waves.
Recall that output is the result of processing data; output devices store or show you those
results. Output can be stored inside the computer itself or on an external storage device,
such as a DVD. You will learn more about storage devices later in this tutorial.
The most common devices for displaying output are monitors and printers. The
monitor shown in Figure 18 is a ﬂ at panel monitor . Most ﬂ at panel monitors use LCD liquid (
crystal display ) technology, which creates the image you see on the screen by
manipulating light within a layer of liquid crystal. This is the same technology used in digital
watches or the time display on a microwave oven. LCD monitors require a backlight.
Flat-panel monitors labeled as LED light emitting diode ) monitors use LEDs to provide (
the backlight. LED backlighting is more energy efﬁ cient than ordinary backlighting. One
problem with LCD monitors is that when you view the monitor from an angle, it can be
hard to see the images on it. LED backlighting helps solve this problem.
Factors that inﬂ uence the quality of a monitor’s output are screen size, resolution,
and dot pitch. Screen size is the diagonal measurement in inches from one corner of
the screen to the other. Most desktop monitors range from 15 to 30 inches. Monitors on
notebook computers range from 12 to 20 inches. The ﬁ rst PC monitors were
characterbased. A character-based display divides the screen into a grid of rectangles, one for
each typed character. A monitor that is capable of displaying graphics, called a graphics
display , divides the screen into a matrix of small dots called pixels . Resolution is the
number of pixels the monitor can display. Standard resolutions range from 640 × 480
to 1600 × 1200. The resolution you use depends on your monitor size. If your screen
is small, a 1600 × 1200 resolution will make the objects on the screen too small to