dot-matrix similar to a dot-matrix printing device. Nor-
mally, it is the display device manufacturer who will
decide on a specific matrix size—say, 7 by 12 (for a total
of 84 dots or pixels) to display each character of text
(see figure 1-14). The more pixels used to form charac-
ters, the higher is the resolution. Most display devices
use 25 rows of 80-character lines when displaying text,
and there are some that will display 50 rows of 132-
character lines in what is called a compressed mode.
Graphics output consists of complex picture
images, which brings us to the term bit mapping. Bit
mapped graphics use a technique whereby each dot or
pixel on the screen can be addressed and individually
controlled by the user.
This allows you to create
virtually any type of image on the screen. Knowing this
should give you abetter understanding and appreciation
of why resolution is so important, especially if you are
viewing two documents on the screen at the same time,
side-by-side, or working with three-dimensional
graphics.
The type of monitor or display device you have on
your microcomputer will often dictate what type of
display/graphics board you can plug into your system
unit. The key word here is compatibility. Some
display devices can automatically switch between any
standard display/color graphics card. Having such a
display device or monitor allows you to upgrade the
video/ graphics board in the system unit without having
to upgrade the display unit. However, not all display
devices are designed to accept the different types of
video boards available primarily because of their
resolution characteristics. It is important that you read
all the documentation that comes with your micro to
determine whether or NOT your display device will be
compatible with the video/graphics board you want to
install.
Figure 1-14.—The letter “L” as formed within a 7- by 12-dot
matrix.
Keyboards
Of all the components that make up a
microcomputer, you will become most familiar with the
keyboard. It will probably be your primary means for
inputting programs and data on microcomputers.
Keyboards come in many shapes and sizes, have
different numbers and arrangements of keys, differ in
respect to touch, and have special keys to allow you to
communicate specific software commands. Most
manufacturers have designed their keyboards as
separate devices so you can place them wherever it is
convenient. Other manufacturers have designed their
keyboards into the display/monitor device or system
unit.
The important things you need to know about
keyboards are the types of keys and the function and
placement of each. All keyboards have the alphabetic
characters (upper and lower case), numbers, and some
special characters. In addition, keyboards have special
function keys and control keys that are defined by the
operating system or the program. We will briefly
describe an example keyboard and explain some of the
more common keys you are likely to use.
LETTERS, NUMBERS, AND SPECIAL
CHARACTER KEYS.— The arrangement of letter,
number, and special character keys may vary. The
QWERTY keyboard shown in figure 1-15 has the same
format as the conventional typewriter.
1-16
Figure 1-15.—QWERTY keyboard.
