A+ - Chapternot that one 1

clashjudiciousElectronics - Devices

Nov 8, 2013 (3 years and 7 months ago)



What Is a Computer

EC 4

Types of Computers

EC 6

Computer Hardware

EC 9

Data Communications

EC 22

Computer Software

EC 26

Chapter 1

What Is a Computer?

Computers have become essential tools in almost every type of activity in virtually every type of

A computer is defined as an electronic device that accepts input, processes data, stores data, and
produces output. It is a versatile tool with the potential to perform many different tasks.

A computer system includes a computer, peripheral devices, and software. The physical components
of a computer are referred to as hardware. The design and construction of a particular computer is
referred to as its architecture, or configuration. The technical details about each component are
called specifications. For example, a computer system might be configured to include a printer; a
specification for that printer might be a print speed of eight pages per minute or the capacity to
print in color. The computer itself takes care of the processing function, but it needs additional
components, called peripherals, to accomplish its input, output, and storage functions.



refers to the intangible components of a computer system, particularly the programs, or lists
of instructions, that the computer needs to perform a specific task. Software is the key to a
computer’s versatility. When your computer is using word processing soft ware

for example, the
Microsoft Word program

you can type memos, letters, and reports. When your computer is using
accounting software, you can maintain information about what your customers owe you and
display a graph showing the timing of customer payments.

The computer processes the report according to your commands and
instructions contained in the software

the title becomes centered and all the text double
Processing changes the data you have input, for example, by moving text, sorting lists, or perfomiing
calculations. Or, you might choose to import from another computer an illustration, text, or numeric data
such as stock prices. This processing takes place on the main circuit board of the computer, also
referred to as the motherboard, which contains the computer’s major electronic components. The
electronic components of the main circuit board are referred to as processing hardware.

Using a computer to type your report has several advantages. The first is the speed at which you can
perform the task. Second, the capability of storing the answer and using it over and over again, in so
many different ways, makes using a computer the most effective way to perform many personal and
clerical tasks. Finally, an important advantage is sharing data and output with others. You make a note
to find out whether Paik employees will need to share their data.

Types of Computers


Personal computers are not the only way to compute; there are other
types of computers, which are classified by their size, speed, and
cost. Microcomputers, also called personal computers (PCs), are the
computers typically used by a single user, usually at home or at the
office. They come in many shapes and sizes, as you can see in

A standard desktop microcomputer
fits on a desk and runs on power
from an electrical wall outlet. The
display screen is usually placed on
top of the horizontal desktop case.

A microcomputer
with a tower case
contains the same
basic components
as a standard
but the vertically
oriented case is
large and allows
more room for
expansion. The
tower unit can be
placed on the
floor to save desk

A notebook computer
is small and light,
giving it the advantage
of portability that
standard desktop
computers do not
have. A notebook
computer can run on
power from an
electrical outlet or

A personal digital assistant
(PDA), or palm
computer achieves even
more portability than a
notebook computer by
shrinking or eliminating
some standard
components, such as the
key board. On a
keyboardless PDA, a
sensitive screen
accepts characters drawn
with your finger. PDAs
easily connect to desktop
computers to exchange
and update information.


Terminals act as each user’s main
input and output device. The
terminal has a keyboard for input
and a display screen for output,
but it does not process the user’s
data. Instead, processing
requests must be transmitted from
the terminal to the minicomputer.

stores data for
all the users in
one centralized

Mainframe computers,

are larger and more powerftil than minicomputers. As with a minicomputer,
one mainframe computer performs process ing tasks for multiple users on
terminals. However, the mainframe can handle many more users than a
minicomputer. Mainframes are typically used to provide centralized storage,
processing, and management for large amounts of data. The price of a
typical mainframe computer can be several hundred thousand dollars.

The largest and fastest computers,
called supercomputers, were first
developed for high
volume computing
tasks such as weather prediction.
Supercomputers like the one shown in
Figure 6 are also being used by large
corporations when the tremendous
volume of data ould seriously delay
processing on a mainframe computer.
Although its cost can be several million
dollars, a supercomputer’s processing
speed is so much faster than that of
microcomputers, minicomputers, and
mainframes that the investment can be

Computer Hardware

You input data and commands by using an input device such as a keyboard or a mouse.
The computer can also receive input from a storage device. This section takes a closer
look at the input devices you might use. Output and storage devices are covered in later

The most frequently used input device is a keyboard. The top keyboard in Figure 7 is a
standard 101
key keyboard. Newer keyboards such as the bottom keyboard in Figure 7,
are ergonomic, which means that they have been designed to fit the natural placement
of your hands and should reduce your risk of repetitive
motion injuries. All keyboards
consist of three major parts: the main keyboard, the keypads, and the function keys.

input Devices


All microcomputers also should be equipped with a pointing device.

The pointing device controls a pointer on the display screen. Using a pointing device

an important skiil because most microcomputers depend on such devices to select
com mands and manipulate text or graphics on the screen. Computers that input from
terminals do not normally use pointing devices. Computers used for presentations
often feature remote input devices, such as the remote control used for a TVIVCR.
The remote input device allows you to control the pointer from the back of the

Now that you have read about input devices, refer back to the computer
advertisement shown in Figure 1 at the beginning of the chapter. Can you list the
input devices included with the adver tised system? A mouse and a keyboard are
considered essential peripheral devices, so advertise ments do not always list them.
Unless the ad specifies some other input device, such as a track ball, you can safely
assume the computer comes equipped with a traditional keyboard and mouse.

A track point is a small

like device
embedded among

typing keys. To control
the on

screen pointer,
you push the track point
up, left, right, or down.
Buttons for clicking and
clicking are
located in front of the

A track ball is like an

mouse. By rolling
the ball with your
fingers, you control
the on
pointer. Buttons for
clicking are often
located above or to
the side of the track

A touch pad is a
device. By dragging
your finger over the
surface, you control
the on
pointer. Two
buttons equivalent
to mouse buttons
are located in front
of the touch pad.