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Power users often use so
ftware that allows them to work with graphics and multimedia.
Computer
-
aided design

(
CAD
)
software

assists in creating engineering, architectural, and
scientific designs.
Desktop publishing
(
DTP
) software is used to design and produce
sophisticated documen
ts. DTP is developed specifically to support
page layout
, which is the
process of arranging text and graphics in a document.

Paint software

is used to draw graphical
images with various on
-
screen tools.
Image editing software

provides the capability to mod
ify
existing images.
Video editing software

and
audio editing software

can be used to modify
video
and
audio

segments.

Multimedia authoring software

is used to create electronic interactive presentations that can
include text, images, video, audio, and ani
mation. Web page authoring software is designed to
create Web pages and to organize, manage, and maintain Web sites.

Many software applications are designed specifically for use at home or for personal or
educational use.
Integrated software

combines seve
ral productivity software applications that
share a similar interface and common features into a single package.

Personal finance software

is an accounting program that helps pay bills, balance a checkbook, track income and expenses,
follow investments, an
d evaluate financial plans.

Legal software

assists in the creation of legal
documents and provides legal advice.
Tax preparation software

guides users through the
process of filing federal taxes.
Personal DTP software

helps develop conventional documents
b
y asking questions, presenting predefined layouts, and supplying standard text.

Photo
-
editing software

is used to edit digital photographs. A
clip art/image gallery

is a
collection of clip art and photographs that can be used in all types of documents.
Hom
e
design/landscaping software

assists with planning or remodeling.

Educational software

teaches a particular skill and exists for about any subject.
Reference software

provides valuable
and thorough information for all individuals.
Entertainment software

i
ncludes interactive
games, videos, and other programs designed to support a hobby or provide amusement.

One of the main reasons people use computers is to communicate and share information.
E
-
mail
software

is used to create, send, receive, forward, store,

print, and delete
e
-
mail

(
electronic
mail
). A
Web browser

is a software application used to access and view Web pages. A
chat
client

is software that allows you to connect to a
chat room
, which permits users to chat via the
computer. A
newsreader

is a software program used to participate in a
newsgroup
, which is an
online area on the Web where users conduct written discussion about a particular subject. An
instant messenger

is a software program installed to use
instant messaging

(
IM
), a real
-
time

communications service that notifies you when one or more people are online and then allows
you to exchange messages or files.
Groupware

is a software application that helps groups of
people on a network work together and share information. A
videoconfere
nce

is a meeting
between two or more geographically separated people who use a network or the Internet to
transmit audio and video data.






Identify various products available as Web applications

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A
Web application

is a software application that exists o
n a Web site. To access the Web
application, you visit the Web site that offers the program. Some Web applications are free; for
others, you pay for use, service, support, or when a certain action occurs.
Web
-
based training

(
WBT
) is a type of CBT (computer
-
based training) that uses Internet technology. Many Web
sites offer WBT to the general public. An
application service provider

(
ASP
) is a third
-
party
organization that manages and distributes software and services on the Web.





Describe the learning ai
ds available with many software applications

Many software applications and Web sites provide learning aids.
Online Help

is the electronic
equivalent of a user manual. Usually integrated into an application software package, online
Help often is
context
-
se
nsitive
, meaning that the Help information is related to the current task
being attempted. Most online Help also provide links to Web sites that have a FAQs page.
FAQs

(Frequently Asked Questions) supply answers to common queries. Many books are available
to
help you learn to use the features of a personal computer application package. A
wizard

is an
automated assistant that helps complete a task by asking questions and then performing actions
based on the answers.








Expand Your
Knowledge

1.

Application software

2.

System software

3.

The user interface

4.

Starting an application

5.

Software

6.

Web applications

7.

Learning aids

Here you will find additional information that will expand and enhance your knowledge beyond
that contained in your textbook. Compare this information to what may
be provided in a
traditional classroom by your instructor or peers.





Application Software

Popular types of application software can be categorized by their general use: productivity
software, graphics design/multimedia software,
home/personal/educational software, and
communications software. An application can belong to more than one category. For example, an
e
-
mail program can be considered both productivity software and communications software.





System Software

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Many applica
tion programs are designed to run with a specific operating system. When shopping
for an application software package, buyers must make sure they have a compatible operating
system. A software package designed to be used with the Macintosh operating system

may not
work with the Windows operating system. The operating system version also is important. An
application designed for Windows XP may not work with Windows 3.1. Yet, because most
operating systems are downward compatible, software written for earlier

versions of an operating
system (such as Windows 98) usually can be used with recent versions of the operating system
(such as Windows XP).





The User Interface

The user interface plays a key role in application software. Studies have found that GUI us
ers
generally complete tasks more accurately, work faster, are more productive, and feel less fatigue
than users of a text interface. The Macintosh operating system


the first popular GUI


actually
was developed from an earlier GUI
-
based operating system

created by Xerox.

The first version of Windows (1985) imitated the Macintosh’s GUI (Apple sued Microsoft,
unsuccessfully, for copyright infringement). Although some users still feel the Macintosh
interface is superior, today some form of Windows is used o
n almost 90 percent of personal
computers. Because of this, even competitive products often use similar features, such as the
same menu names.





Starting an Application

To
click

an object on the screen, you move the pointer to the object and then press and release a
button on the mouse. Often, applications also can be started by double
-
clicking the icon that
represents the application.

When an application is started, the right
-
ha
nd corner of the application window title bar usually
displays three buttons:



Minimize





When clicked, this button reduces a window to a button on the taskbar.



Restore





When clicked, this button returns a window to its initial size. When a
window do
es not fill the desktop, the Restore button is replaced by a Maximize button



that, when clicked, enlarges the window so it covers the entire desktop.



Close





When clicked, this button closes the window. The Close button removes the
window from the de
sktop and its button from the taskbar.

A dialog box can contain option buttons, check boxes, text boxes, and command buttons. Option
buttons stipulate desired alternatives; check boxes turn specific capabilities on or off; text boxes
allow text to be enter
ed; and command buttons immediately perform an action, such as
implementing (OK) or ignoring (Cancel) the choices made in a dialog box. Shortcut menus can
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change depending on where the pointer rests when the mouse is right
-
clicked. Dimmed
commands on a men
u or shortcut menu are unavailable.

Some applications use automatically display a smart tag when you perform a certain action.
Clicking the smart tag displays a menu of commands related to the action.





Software

Word processing software is used for crea
ting, editing, formatting, saving, and printing
documents. In the modern office, word processing software has replaced the typewriter for
almost all written work. The editing capabilities of word processing software have altered the
creative process. The f
reedom to express yourself without reservation, knowing you easily can
revise what you have written, can improve the quality of written work. It is good practice to save
a document before printing it. When a document is saved, it exists as a file, or named

collection
of data, instructions, or information. A file name uniquely identifies each file. Restrictions on file
names once were severe; file names could be no more than eight characters long, and many
characters, including spaces, could not be used. In
Windows XP, however, a file name can have
up to 255 characters, including spaces.

Some spreadsheet programs offer more than 200 internal functions. When creating a spreadsheet,
formulas and functions usually must be preceded by a special character (such as

=, +, or @) to
distinguish them from labels or values. Formulas use cell references, or addresses, of cells that
contain values. When formulas are copied from one cell to another, the cell references change to
reflect the new location. This update is call
ed relative referencing. Another powerful capability,
called goal
-
seek, finds what value is needed to reach a specified goal.

While spreadsheet packages can manage data tables of a few thousand records, database software
can efficiently handle much larger
data tables. In a database, common data types include text,
numeric, currency, date, memo, hyperlink, and object. When identifying data types, numbers
treated as text (such as zip codes, Social Security numbers, or telephone numbers) sometimes are
referred

to as alphanumeric data because they are not used in calculations. The results of a
database query are placed in an ANSWER table.

Although introduced years after word processing and spreadsheet software, presentation graphics
software has had almost as gr
eat an impact on business, and on how people do business, as either
of the older applications. Presentations often include an outline with the text from each slide,
audience handouts that can be distributed to the audience, and a notes page with additional

notes
for the presenter. Some presentation graphics packages offer templates for various presentations
(company meeting, financial report, marketing plan, progress report, employee orientation,
training, and so on).

PIMs essentially are “free style” datab
ase managers. They are very popular with people who
spend much of their time in business travel. These people, often called road warriors, find PIMs
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a valuable part of the arsenal they bring to their daily battles. Like a daily planner, PIMs must be
review
ed regularly to be effective.

Unlike word processing software, DTP software increases hardware requirements. Because of its
relatively low cost (an advanced DTP system can be purchased for less than $10,000) and the
speed, control, security, and flexibilit
y offered by desktop publishing, many companies are using
DTP instead of outside printing firms for their publishing needs.

Paint software and image editing software have had a tremendous impact on commercial art.
Commercial artists praise the capabilities

offered by these applications. At the same time, many
feel these applications have led clients to demand more, both in terms of time and expectations.
As a result, some commercial artists believe their income, actually has dropped because of
graphic softw
are.

Most software for home, personal, and educational use is relatively inexpensive. It still pays to
shop around. Prices for some software for home/personal use, such as integrated software, can
vary greatly for the same brand depending on the vendor. So
me personal finance packages can
prepare reports on income and expenses, budget, net worth, taxes, and investments.

Personal finance software wizards (automated assistants) can help to balance accounts, prepare
budgets, plan mortgages, calculate savings, a
nd arrange retirements. Legal software is designed
to facilitate creation of standard documents; unusual circumstances might still demand the
services of a lawyer. Tax preparation software also is best used by people in fairly common
circumstances.

For som
e students, educational software is a welcome alternative to traditional classes, allowing
them to work privately at their own pace. Reference software articles often include links that,
when clicked, display related articles. Because referenced material c
an change frequently, some
reference software packages can be updated via the World Wide Web.

Computer communications touch everyone’s life. Consider the ATM that “knows” a bank
balance even though it is located 500 miles from the bank. Many e
-
mail
programs allow users to
send “registered mail” with a return receipt guaranteeing the recipient received the message. E
-
mail and personal information management (PIM) software sometimes also are considered part
of groupware. Although e
-
mail has assumed an
important role in business messages, traditional
paper letters and memos still are used In fact, some maintain that the amount of paper
correspondence has increased.





Web Applications

Web applications can be a better buy than packaged applications. For

example, a $50 packaged
antivirus program can be replaced by a Web application that costs less than $30 annually, is
updated frequently, and uses less space on a hard disk. In addition, packaged software might
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include features you will never use, which in
creases the cost of the package. Often, you can use
the standard version of a similar Web application for less money or even for free, and only pay
more for the additional features you want. Web applications can save businesses money with
reduced installat
ion, upgrade, and maintenance costs. Some social analysts believe that the lower
cost of Web applications also can help close the “digital divide.”

For Web application vendors, benefits include easier updating and debugging (error correcting),
removal of p
ackaging and distribution costs, and elimination of software piracy (the illegal
copying and selling of software). Despite their advantages, analysts point out that Web
applications may not be right for everyone. For some consumers, paying a monthly fee
ul
timately costs more than the one
-
time purchase of packaged software. Also, many households
do not have the fast Internet connection needed for certain Web applications to run smoothly.
Finally, some people worry that files stored at a Web application site
can be infected with
viruses. Web application vendors believe these worries are groundless and that Web applications
benefit both buyers and sellers.





Learning Aids

In many applications, an audible “beep” indicates an error, and the last entry should b
e reviewed.
Function key
F
1 often is used to activate the Help feature. Some applications have a Help button
that, when clicked, changes the mouse pointer to a Help arrow. This arrow can be used to obtain
help on a command, button, or bar by pointing at
the item and clicking. Many software
developers have eliminated user’s manuals in favor of extensive online Help. Computer stores
occasionally carry a few trade books, but entire aisles of computer
-
related books can be found in
most large book stores.

For
some applications, other learning aids, such as tutorials or keyboard templates, are available.
Tutorials are step
-
by
-
step instructions using real examples that show how to use an application.
Tutorials can be printed, software
-
based, or Internet
-
based. Ke
yboard templates (plastic sheets
that fit around a portion of the keyboard) illustrate the keyboard commands for various tasks.
Wizards can be used to help create memorandums, meeting agendas, fax cover sheets, flyers,
letters, resumes, charts, forms, repo
rts, awards, pleadings, calendars, postcards, envelopes,
mailing labels, newsletters, and Web pages. Some applications also offer document templates,
which are special documents that provide basic tools for shaping a final document. The
availability of lea
rning aids and support tools is an important consideration in selecting an
application package.




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|
Chapter 1

|
Chapter 2

|
Chapter 3

|
Chapter 4

|
Chapter 5

|
C
hapter 6

|
Chapter 7

|
Chapter 8

|
Site Map

|

Chapter 4:
The Components of the System Unit

|
Overview

|
Expand Your Knowledge

|




Overview

1.

Describe the components in the
system unit

2.

Explain how the CPU uses the
four steps of a machine cycle to
process data

3.

Define a bit and describe how a
series of bits represents data

4.

Differentiate between the
various types of memory

5.

Describe the types of expansion
slots and cards in the system
unit

6.

Explain the difference between
a serial, a parallel, and a USB
port

7.

Describe how buses contribute
to a computer's processing
speed

8.

Identify components in a
notebook computer

9.

Ident
ify components in a
handheld computer

Chapter 4 presented the components in the system unit, described how memory stores data,
instructions, and information, and discussed the sequence of operations that occur when a
computer executes an instruction. The
chapter included a comparison of various microprocessors
on the market today.





Describe the components in the system unit

The
system unit
, sometimes called the
chassis
, is a box
-
like case housing the electronic
components of a computer that are used t
o process data. System unit components include the
processor, memory module, cards, ports, and connectors. Many of the system unit’s components
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reside on a circuit board called the
motherboard
. The motherboard contains many different
types of
chips
, or sma
ll pieces of semiconducting material, on which one or more
integrated
circuits

(
IC
) are etched. An integrated circuit is a microscopic pathway capable of carrying
electronic current. Each IC can contain millions of
transistors
, which act as switches for
el
ectronic signals.





Explain how the CPU uses the four steps of a machine cycle to process data



The
central processing unit

(
CPU
), also called a
processor
, significantly impacts overall
computing power and manages most of a computer’s operations. The C
PU contains the control
unit and the arithmetic/logic unit. The
control unit

directs and coordinates most of the
operations in the computer. For every instruction, the control unit repeats a set of four basic
operations called the
machine cycle
: (1)
fetching

the instruction or data item from memory, (2)
decoding

the instruction into commands the computer understands, (3)
executing

the
commands, and, if necessary, (4)
storing
, or writing the result to memory. The
arithmetic/
logic

unit

(
ALU
) performs th
e execution part of the machine cycle. Specifically, the ALU carries out
three operations:



Arithmetic operations



performing calculations, which include addition,
subtraction, multiplication, and division



Comparison operations



comparing data items to de
termine if the first item is
greater than, equal to, or less than the other item



Logical operations



working with conditions and logical operators such as
AND, OR, and
NOT



Compare and contrast various personal computer processors on the market
today


A pe
rsonal computer’s CPU usually is contained on a single chip, which some call a
microprocessor
. Intel is a leading manufacturer of personal computer processors. Most high
-
performance PCs use a processor from Intel called the
Pentium
®

processor. A second Int
el
brand, called the
Celeron™
, is designed for less expensive PCs. Two more brands, called the
Xeon™

and
Itanium™

processors, are ideal for workstations and low
-
end servers.
Intel
-
compatible processors
have the same internal design as Intel processors and
perform the same
functions, but are made by other companies and often are less expensive. An alternative design
to the Intel
-
style processor, the
Motorola processor
, is found in Apple Macintosh and Power
Macintosh systems. A new type of processor designed
for lower
-
costing personal computers and
Internet appliances, called an
integrated CPU
, combines functions of a processor, memory, and
a video card on a single chip. Today’s processors are equipped with
MMX

technology
, a
built
-
in set of instructions that
manipulates and processes multimedia data more efficiently.
Intel’s
SSE instructions

and AMD’s
3DNow!™

are two other technologies that improve a
processor’s performance of multimedia, the Web, and 3
-
D graphics. To optimize and extend
battery life for noteb
ook computers, Intel® mobile processors use
SpeedStep™ technology

and
AMD processors use
PowerNow!™ technology
.

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Define a bit and describe how a series of bits represents data



Most computers are
digital
, meaning they understand only two discrete
states: on and off. These
states are represented using two digits, 0 (
off
) and 1 (
on
). Each on or off value is called a
bit

(short for
bi
nary digi
t
), the smallest unit of data a computer can handle. Eight bits grouped
together as a unit form a
byte
. A byte

provides enough different combinations of 0s and 1s to
represent 256 individual characters including numbers, letters of the alphabet, punctuation
marks, and other characters.

The combinations of 0s and 1s used to represent data are defined by patterns ca
lled coding
schemes. Popular coding schemes are

ASCII
, EBCDIC, and
Unicode
. Coding schemes make it
possible for humans to interact with a digital computer that recognizes only bits. Every character
you type on a keyboard is converted into a corresponding b
yte, a series of on/off electrical states
the computer can process.





Differentiate between the various types of memory

Memory

is a temporary storage place for data, instructions, and information. Memory stores the
operating system, application program
s, and the data processed by application programs. A byte
is the basic storage unit in memory. Memory size is measured by the number of bytes available
for use. A
kilobyte

(
KB

or
K
) of memory is approximately one thousand bytes, a
megabyte

(
MB
) is approxim
ately one million bytes, and a
gigabyte

(
GB
) is approximately one billion
bytes. The system unit contains several types of memory.

RAM

(
random access memory
) consists of memory chips that the processor can read from
and

write to. Most RAM is
volatile memor
y
, meaning that its contents are lost when the computer’s
power is turned off. Two basic types of RAM chips are dynamic RAM and static RAM.
Dynamic RAM

(
DRAM
) must be re
-
energized constantly or it loses its contents.
Static RAM

(
SRAM
) is faster and more
reliable than DRAM and has to be re
-
energized less often, but it is
much more expensive.

Memory cache
, also called a
cache store

or
RAM cache
, improves processing time by storing
frequently used instructions and data.
ROM

(
read
-
only memory
) refers to memor
y chips that
only can be read and used; that is, they cannot be modified. ROM is
nonvolatile memory

(
NVM
), meaning that its contents are not lost when the computer’s power is turned off. A
variation of the ROM chip, called
programmable read
-
only memory

(
PR
OM
), is a blank chip
on which you can place items permanently.

Flash memory
, also known as
flash
ROM or
flash RAM
, is nonvolatile memory that can be
erased electronically and reprogrammed.
Complementary metal
-
oxide semiconductor
(
CMOS
)
memory
, another type

of memory chip, stores configuration information about the
computer and uses battery power to retain information when the power to the computer is off.

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Describe the types of expansion slots and cards in the system unit


An
expansion slot

is an openin
g, or socket, where you can insert a circuit board into the
motherboard. These circuit boards


called
cards
,
expansion cards
,
boards
,
expansion boards
,
adapters
,
adapter cards
,
interface cards
,
add
-
ins
, or
add
-
ons

--

add new devices or
capabilities to the computer. Four types of expansion cards found in most computers are a video
card, a sound card, a network interface card, and a modem card.

A
video card

converts computer output into a video signal that is sent th
rough a cable to the
monitor, which displays an image. A
sound card

enhances the sound
-
generating capabilities of a
personal computer by allowing sound to be input through a microphone and output through
speakers.

A
network interface card

(
NIC
) is a commun
ications device that allows the computer to
communicate via a network. A
modem card

is a communications device that enables computers
to communicate via telephone lines or other means. Many of today’s computers support
Plug
and Play
, a capability with whic
h the computer automatically can configure expansion boards
and other devices as you install them.

Notebook and other portable computers have a special type of expansion slot used for installing a
PC Card
, which is a thin credit card
-
sized device that adds

memory, disk drives, sound,
fax/modem, and communications capabilities to a mobile computer.





Explain the difference between a serial, a parallel, and a USB port

A cable often attaches external devices to the system unit. A
port

is the interface, or point of
attachment, to the system unit. Ports have different types of
connectors
, which are used to join a
cable to a device.
Male connectors

have one or more exposed pins, while
female connectors

have matching holes to accept the pi
ns. Most computers have three types of ports: serial, parallel,
and USB. A
serial port

is a type of interface that connects a device to the system unit by
transmitting data only one bit at a time. Serial ports usually connect devices that do not require
fa
st data transmission rates, such as a mouse, keyboard, or modem. A
parallel port

is an
interface that connects devices by transferring more than one bit at a time. Many printers connect
to the system unit using a parallel port. A
universal serial bus

(
USB
)

port can connect up to 127
different peripheral devices with a single connector type, greatly simplifying the process of
attaching devices to a personal computer.





Describe how buses contribute to a computer's processing speed

Bits are transferred in
ternally within the circuitry of the computer along electrical channels. Each
channel, called a
bus
, allows various devices inside and attached to the system unit to
communicate with each other. The
bus width
, or size of the bus, determines the number of b
its
that can be transferred at one time. The larger the bus width, the fewer number of transfer steps
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required and the faster the transfer of data. In most computers
word size

(the number of bits the
CPU can process at a given time) is the same as the bus
width. Every bus also has a clock speed.
The higher the bus clock speed, the faster the transmission of data, which results in applications
running faster. A computer has two basic types of buses. A
system bus

connects the CPU to
main memory. An
expansion
bus

allows the CPU to communicate with peripheral devices.





Identify components in a notebook computer

Users with mobile computing needs often have a mobile computer, such as a notebook computer
and/or handheld computer. A notebook computer, also call
ed a laptop computer, can run either
using batteries or using a standard power supply. In addition to the motherboard, processor,
memory, sound card, PC Card slot, and drive bay, the system unit for a notebook computer also
houses other devices, such as th
e keyboard, pointing device, speakers, and display.




Identify components in a handheld computer



Handheld computers run strictly on battery. Similar to desktop and notebook computers,
handheld computers have a system unit that contains electronic compo
nents that process data. A
handheld computer’s system unit also contains a display and may house speakers and some form
of keyboard and/or pointing device. Handheld computers often have an IrDA port so you can
communicate wirelessly with other computers. M
any also include a serial port.








Expand Your
Knowledge

1.

The system unit

2.

The CPU

3.

Processor comparison

4.

Data representation

5.

Memory

6.

Expansion slots and expansion
cards

7.

Ports

8.

Buses

9.

Notebook computers

10.

Handheld computers

Here you will find additional information that will expand and enhance your knowledge beyond
that contained in your textbook. Compare this information

to what may be provided in a
traditional classroom by your instructor or peers.





The System Unit

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The motherboard in the system unit contains different types of chips. Manufacturers package
chips so the chips can be attached to circuit boards, such as

the motherboard. Types of chip
packages include:



Dual inline package

(
DIP
), which consists of two parallel rows of downward
-
pointing thin metal feet (pins)



Pin grid array

(
PGA
)
package
, which holds a larger number of pins because the
pins are mounted on t
he surface of the package



Flip chip
-
PGA

(
FC
-
PGA
)
package
, which places chips on the opposite side (flip
side) of the pins



Single edge contact

(
SEC
)
cartridge
, which connects to the motherboard on one
of its edges





The CPU

The power of personal
computer processor chips (the chips that contain the CPU) has grown at
an astounding rate. As chips become older and more widely used, price cuts usually are
introduced.

Several factors affect CPU processing speed. CPUs in most of today’s personal computer
s use
pipelining
, a technique that increases processing speed by beginning execution of a second
machine cycle instruction before the first instruction is completed. CPUs also use high
-
speed
storage locations, called
registers
, to hold data and instruction
s temporarily. The control unit
relies on a small chip called the
system clock

to synchronize all computer operations. The speed
at which a processor executes instructions is called
clock speed
, or
clock rate
, and is measured
in
megahertz

(
MHz
). The system

clock is a major factor affecting processor speed. A higher
clock speed means the CPU can process more instructions per second.





Processor Comparison

Although once frequently used, the term “microprocessor” is much less common today.

Sometimes you can

upgrade your processor to increase the computer’s performance. There are
three forms of upgrades:



With a
chip for chip upgrade
, the existing processor chip is replaced with a new
one



With a
piggyback upgrade
, the new processor is stacked on top of the old

one



With a
daughterboard upgrade
, the new processor is on a small circuit board
(the
daughterboard
) that plugs into the motherboard

The past three years have seen a steady drop in the cost of computers. PC prices plunged as a
result of lower prices for pr
ocessors, memory chips, and hard drives. Consumers also are
showing increased interest in new less powerful, but less expensive, personal computers that
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work perfectly well for the most popular uses


word processing, Internet access, and
spreadsheet appli
cations. The surge in low
-
priced computer sales has had an impact on Intel, the
world’s largest processor manufacturer. By focusing on making inexpensive processor chips,
rivals AMD and Cyrix are making inroads into Intel’s dominance. Intel’s response, the

Celeron™, has proven popular, but the lower
-
priced chip offers a smaller profit margin.





Data Representation

Just as the decimal system (10 digits) is suited to human anatomy (10 fingers), the
binary
system

(2 digits) is perfect to represent the on
-
off states (2 states) of a computer. Basic coding
standards make it possible for components within computers to communicate, allow
manufacturers to be confident that the components they produce will operate correc
tly in a
computer, and enable consumers to purchase components that are compatible with their systems.
In the ASCII
-
8 and EBCDIC codes, the first four characters represent the zone, and the last four
characters represent the digits 1 through 8. ASCII, orig
inally a seven
-
bit code, was expanded to
eight bits in an effort to provide for symbols used in other nations. Unicode, a 2
-
byte (16
-
bit)
code, can represent 2
16
, or 65,536, characters. The system employs the codes used by ASCII and
also includes other alp
habets (such as Cyrillic and Hebrew), special characters (including
religious symbols), and some of the “word writing” symbols used by various Asian countries.






Memory

Because computers use the binary number system, the actual values for the units in

which
memory and storage are measured are based on powers of 2. For example, one kilobyte = 2
10

=
1,024.


RAM’s volatility, and its ability to be changed, are its most distinguishing characteristics. When
RAM is purchased it comes in banks of nine chips


eight are needed to represent a byte and the
ninth is needed for parity. RAM chips usually are packaged on small circuit boards called
single
inline memory modules

(
SIMMs
) or
dual inline memory modules

(
DIMMs
) that are inserted
into the motherboard. Durin
g the past 20 years, the price of RAM has dropped an average of 20
percent each year, but its capacity has more than doubled every two years.

Similar to flash ROM, another variation of ROM, called
EEPROM

(
electrically erasable
programmable read
-
only memor
y
), can be erased electrically and rewritten. Because of its
nonvolatile nature, EEPROM is used in electronic cash registers to store item prices.


The amount of time it takes the processor to read data from memory, called
access time
, directly
affects how

fast the computer can process data. Memory access time is measured in terms of
nanoseconds
, or billionths of a second.

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Expansion Slots and Expansion Cards

Plug and Play was a much
-
touted feature of the Windows 95 and Windows 98 operating systems.


A

PC Card slot, usually located on the side of a notebook computer, allows a PC Card to be
changed without having to open the system unit. There are three types of PC Cards:



Type I cards

add memory capabilities to the computer



Type II cards

contain communications devices



Type III cards

house devices such as hard disks





Ports

Port connectors are devised to be foolproof


each is designed so it can fit only one type of
socket in only one correct position. Serial ports always are male on th
e system case. Cables
connected to parallel ports often are employed over shorter distances.

Special
-
purpose ports include:



1394 port


a port that can connect multiple devices requiring faster data
transmission speeds such as digital cameras and DVD drive
s



MIDI (musical instrumental digital interface) port


a special type of serial port
designed to connect the system unit to a musical instrument



SCSI (small computer system interface) port


a high
-
speed parallel port used to
attach peripheral devices such

as disk drives and printers



IrDA port


a port that allows wireless devices to transmit signals to a computer
via infrared light waves





Buses

A highway analogy can help clarify how bus width affects the speed of data transfer. Data moves
like cars


t
he more lanes (greater the bus width) the faster the traffic (data) flow. Ideally, buses
used to transfer data should be large enough to use the processing power of registers. Sometimes,
however, manufacturers reduce bus size to cut costs.

Word size, whic
h indicates the number of bits processed in each machine cycle, has been
compared to the amount of coffee produced with each turn of a coffee grinder’s handle.
Theoretically, if word size doubles then processor throughput also could double.

The types of e
xpansion buses on a motherboard determine the types of cards you can add to a
computer. Types of expansion buses include:

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An
ISA

(
Industry Standard Architecture
)
bus
, the most common and slowest
expansion bus, connects to devices such as a mouse, modem ca
rd, sound card, and
low
-
speed network card



A
local bus

is a high
-
speed expansion bus used to connect higher speed devices
such as hard disks



An
Accelerated Graphics Port

(
AGP
) is a bus designed by Intel to improve the
speed with which 3
-
D graphics and vide
o transmit



The
universal serial bus

(
USB
) and
1394 bus

are buses that eliminate the need to
install expansion cards into expansion slots



A
PC Card bus

is the expansion bus for a PC Card





Notebook Computers

A typical notebook computer often has a
keyboard/mouse, IrDA, serial, parallel, video, and USB
ports. The keyboard/mouse port allows users who are uncomfortable with a notebook computer’s
smaller keyboard and less
-
traditional pointing devices (often a touch pad or pointing stick) to
connect a fu
ll
-
sized keyboard or a mouse to the computer.





Handheld Computers

One of the most popular handheld computers is the Palm Pilot from 3Com. First introduced in
1996, a recent version, Palm IIIc, offers a color screen and an expandable, full
-
sized keyboa
rd.
Another pioneering handheld computer is Visor from Handspring. Visor runs the Palm operating
system and features an expansion slot that can accommodate add
-
ons such as digital cameras and
music players. Visor’s greatest innovation, however, may be the
slot in the back, which can
accommodate modules with various functions including a pager, an MP3 music player,
videogame cartridges, and a module that converts the Visor into a cell telephone.




Home

>
Notes

>
Discovering Computers

>
Chapter 5


|
Chapter 1

|
Chapter 2

|
Chapter 3

|
Chapter 4

|
Chapter 5

|
Chapter 6

|
Chapter 7

|
Chapter 8

|
Site Map

|

Chapter 5: Input

|
Overview

|
Expand Your Knowledge

|


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Overview

1.

Describe the two types of
input

2.

List the characteristics of a
keyboard

3.

I
dentify various types of
keyboards

4.

Identify various types of
pointing devices

5.

Explain how a mouse works

6.

Describe different mou
se types

7.

Explain how voice recognition
works

8.

U
nderstand how to input data
into a handheld computer

9.

Identify the uses of a digital
camera

10.

Describe the various techniques
used for video input

11.

Describe the uses of PC video
cameras and web cams

12.

Explain how scanners and other
reading devices work

13.

Identify alternative input
devices for physically
challenged users

In this chapter, you learn what is input and what are input devices. The keyboard is presented
and different keyboard types are described. You are introduced to various pointing
devices, such
as the mouse, trackball, touchpad, pointing stick, joystick, touchscreen, and pen input. Scanners
and reading devices, including optical scanners, optical readers, magnetic ink character
recognition readers, and data collection devices are ex
plained. You learn about digital cameras,
audio input, speech recognition, video input, and videoconferencing. Finally, input devices for
physically challenged users are explored.





Describe the two types of input

Input is any data or instructions enter
ed into the memory of a computer. Two types of input are
data and instructions. Data is a collection of unorganized items that can include words, numbers,
pictures, sounds, and video. A computer processes data into information, which is organized,
meaningf
ul, and useful. Instructions can be in the form of programs, commands, or user
responses. A program is a series of instructions that tells a computer how to perform the tasks
necessary to process data into information. A command is an instruction given to
a computer
program. A user response is an instruction you issue to the computer by responding to a question
posed by a computer program. Any hardware component that allows you to enter data, programs,
commands, and user responses into a computer is an inpu
t device.





List the characteristics of a keyboard

The keyboard is an input device that contains keys you press to enter data into a computer.
Desktop computer keyboards usually have from 101 to 105 keys, while keyboards for smaller
computers contain fe
wer keys. All keyboards have a typing area used to type letters of the
alphabet, numbers, punctuation marks, and other basic characters. Many desktop computer
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keyboards also have a numeric keypad designed to make it easier to enter numbers, function keys
p
rogrammed to issue commands and accomplish certain tasks, arrow keys used to move the
insertion point (a symbol on the screen that indicates where the next typed character will
display), and toggle keys that can be switched between two different states.





Identify various types of keyboards

A standard computer keyboard sometimes is called a QWERTY keyboard because of the layout
of its typing area. An enhanced keyboard has 12 function keys along the top row, 2 ctrl keys, 2
alt keys, and a set of arrow and

additional keys between the typing area and the numeric keypad.
Cordless keyboards transmit data via infrared light waves. Keyboards for notebook and handheld
computers usually have smaller and fewer keys than desktop computers. A portable keyboard is
a f
ull
-
sized keyboard you can attach to and remove from a handheld computer. Some
manufacturers have designed ergonomic keyboards to reduce the chance of workplace injuries.
The goal of ergonomics is to incorporate comfort, efficiency, and safety into the des
ign of
workplace items.





Identify various types of pointing devices

In a graphical user interface, the pointer is a small symbol on the screen. A pointing device is an
input device that allows you to control the pointer. Common pointing devices include

the mouse,
trackball, touchpad, pointing stick, joystick, touch screen, light pen, and a stylus. A mouse is a
pointing device, designed to fit comfortably under the palm of your hand, that is moved across a
flat surface. A trackball is a stationary pointi
ng device with a ball mechanism on its top. A
touchpad is a flat, rectangular pointing device that is sensitive to pressure and motion. A
pointing
-
stick is a pressure
-
sensitive pointing device shaped like a pencil eraser that is positioned
between keys on
the keyboard. A joystick is a vertical lever mounted on a base. A light pen is a
handheld device that contains a light source or can detect light. A touch screen is a touch
-
sensitive display on the screen. A stylus looks like a ballpoint pen but uses press
ure, instead of
ink, to write text and draw lines. An electronic pen can be used on a graphics tablet, which
consists of a flat, rectangular, electronic plastic board used to input graphical data.





Explain how a mouse works

As you move a mouse across a

flat surface, the movement is translated into signals that are sent
to the computer, and the pointer on the screen also moves. When you move the mouse to the
right, the pointer moves to the right on the screen. For Windows users, the top of a mouse has at

least two buttons and sometimes also a wheel. Generally, you use a mouse to move the pointer
on the screen to an object and then press a button, or click, to perform a certain action on that
object. Other operations you can perform using a mouse include r
ight
-
click, double
-
click, drag,
right
-
drag, rotate wheel, and press wheel button.





Describe different mouse types

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A mechanical mouse has a rubber or metal ball on its underside. When the ball rolls in a certain
direction, electronic circuits in the mou
se translate the movement into signals that are sent to the
computer. For better traction, you should place a mechanical mouse on a mouse pad. An optical
mouse has no moving parts; instead it uses devices that emit and sense light to detect the
mouse’s mov
ement. An optical mouse can be used on nearly all surfaces, is more precise than a
mechanical mouse, and does not require cleaning. A cordless mouse, or wireless mouse, is a
battery powered device that transmits data using wireless technology, such as radi
o waves or
infrared light waves. A cordless mouse uses technology very similar to that of a cordless
keyboard.





Explain how voice recognition works

Voice input is the process of entering data by speaking into a microphone that is attached to the
sound
card on a computer. Voice recognition is the computer’s capability of distinguishing
spoken words. The first voice recognition programs were speaker dependent. With speaker
-
dependent software, the computer makes a profile of your voice, which means you hav
e to train
the computer to recognize your voice. Today, most voice recognition programs use speaker
-
independent software, which has a built
-
in set of word patterns and does not have to be trained to
recognize your voice. Some voice recognition software req
uires discrete speech, meaning that
you have to speak slowly and separate each word with a short pause. Most voice recognition
products, however, support continuous speech, allowing you to speak in a flowing conversational
tone.





Understand how to inpu
t data into a handheld computer

To satisfy the input needs of many different types of users, handheld computers provide many
different ways to input data. A handheld computer typically includes a basic stylus. With the
stylus, you can enter data using an o
n
-
screen keyboard or using handwriting recognition software
that translates handwritten letters and characters into symbols the computer understands. Other
input alternatives available with some handheld computers include attaching a full
-
sized
keyboard, t
ransferring data from a desktop computer, using voice input, and attaching a digital
camera.





Identify the uses of a digital camera

A digital camera is used to take pictures and store the photographed images digitally instead of
on traditional film. Pi
ctures are stored on a storage medium, such as a floppy disk, SuperDisk,
Clik! disk, PC Card, compact flash card, memory stick, mini
-
CD, or microdrive. Many digital
cameras allow you to review and edit the images while they are in the camera. You also can
download, or transfer a copy of, the stored image to a computer. Once on a computer, the
pictures can be edited with photo
-
editing software, printed, faxed, sent via electronic mail,
included in another document, or posted to a Web site. There are three ba
sic types of digital
cameras. A studio camera is a stationary digital camera used for professional studio work. A
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field camera is a portable camera, often used by photojournalists, that has many lenses and other
attachments. A point
-
and
-
shoot camera is mor
e affordable and lightweight and provides
acceptable quality photographic images for the home or small business user.





Describe the various techniques used for video input


Video input, or video capture, is the process of entering a full
-
motion
recording into a computer
and storing the video on a storage medium. Many video devices use analog video signals. To
input video from these devices, the device is plugged into a video capture card, an expansion
card that converts the analog signal into a d
igital signal the computer can understand. A digital
video (DV) camera is a new generation of video camera that records video as digital signals,
instead of using analog signals, and therefore does not require a video capture card. Video files
can demand h
uge amounts of storage space. Video compression reduces the size of video files by
recognizing that only a small portion of an image changes from frame to frame. Instead of
storing every frame in its entirety, a video compression program might store an ini
tial frame and
then store only the changes from one frame to the next. A video decoder is a card that
decompresses video. A video digitizer can be used to capture an individual frame from a video
and save the still picture in a file.





Describe the uses

of PC video cameras and Web cams


A PC camera is a DV camera that allows home users to record, edit, capture video and still
images, and make video telephone calls on the Internet. During a video telephone call, both
parties can see each other as they tal
k. Although usually placed on top of the monitor and
attached to a computer’s USB port, some PC cameras are portable and can be used anywhere. A
Web cam is a video camera whose output displays on a Web page. Some Web sites have live
Web cams that display s
till pictures and update the displayed images at specified time intervals.





Explain how scanners and other reading devices work


Scanners and optical readers can capture data from a source document, which is the original form
of the data. A scanner is
a light
-
sensing input device that reads printed text and graphics and then
translates the results into a form a computer can use. One of the more popular scanners is a
flatbed scanner, which works similarly to a copy machine except it creates a file of the

document
in memory instead of a paper copy. Many scanners include OCR software, which converts a
scanned image into a text file that can be edited. An optical reader uses a light source to read
characters, marks, and codes and converts them into digital d
ata that a computer can process.
Three types of optical readers are optical character recognition, optical mark recognition, and bar
code scanner. Optical character recognition (OCR) is a technology that reads typewritten,
computer printed, or handwritten
characters from ordinary documents and translates the images
into a form that the computer can understand. Optical mark recognition (OMR) devices read
hand
-
drawn marks such as circles or rectangles. A bar code scanner uses laser beams to read bar
codes, wh
ich are identification codes consisting of vertical lines and spaces of different widths.
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Another type of reader, called a magnetic
-
ink character recognition (MICR) reader, reads text
printed with magnetized ink and is used almost exclusively by the bankin
g industry.





Identify alternative input devices for physically challenged users


Whether at work or at home, it may be necessary to obtain input devices that address physical
limitations. Voice recognition is ideal for blind or visually impaired users,

but several other input
devices also are available. A keyguard, which is placed over the keyboard, allows people with
limited hand mobility to rest their hands on the keyboard and guides a finger or pointing device
so that only one key is pressed. Keyboar
ds with larger keys and on
-
screen keyboards on which
keys are pressed using a pointing device also can help. Pointing devices such as small trackballs
controlled with a thumb or one finger and head
-
mounted pointers also are available for users
with motor d
isabilities. Two new developments are gesture recognition and computerized
implant devices. With gesture recognition the computer will be able to detect human motions.
Computerized devices implanted in the brain will allow paralyzed individuals to transmit

signals
to the computer.








Expand Your
Knowledge

1.

Input

2.

The keyboard

3.

Keyboard Types

4.

Pointing devices

5.

Using a mouse

6.

Mouse types

7.

Voice recognition

8.

Handheld computer input

9.

Digital cameras

10.

Video input

11.

PC video cameras and web
cams

12.

Scanners and reading devices

13.

Input devices for p
hysically
challenged users

Here you will find additional information that will expand and enhance your knowledge beyond
that contained in your textbook. Compare this information to what may be provided in a
traditional classroom by your instructor or peer
s.





Input

Of the four operations in the information processing cycle


input, process, output, and storage


input is the operation to which computer users are most closely linked and on which each
subsequent action depends.

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Typed commands use
keywords


specific words, phrases, or codes that a program recognizes as
instructions. Keywords are an essential element of command
-
driven programs, such as DOS. The
problem with keywords is that:




they must be memorized, and




they must be entered correct
ly

This makes command
-
driven programs difficult to use. Menu
-
driven programs and graphical
user interfaces eliminate the problems of having to memorize and correctly type keywords.





The Keyboard

Data entered through the keyboard averages about one error for every 300 characters, while data
entered more directly, such as with a scanning device, averages only one error for every 3
million characters. Nevertheless, the keyboard continues to be the mo
st popular input device.
Some special keys


ALT
,
CTRL
, and
SHIFT



almost always are used in combination with
other keys. Desktop computer keyboards generally have two ways to enter numbers


the
numeric keypad and the row of number keys above the alphabe
tic keys. Think of situations in
which both would be used. The numeric keypad also contains arrow keys, but these keys are
active only when the keypad is turned off. Although the purpose of function keys varies, some
developers have tried to standardize ce
rtain keys (such as using
F
1 to access online Help). In
addition to the
NUM


LOCK

key, other toggle keys are the
CAPS LOCK

key and the
INSERT

key. Unlike the
CAPS LOCK

key on a typewriter, the
CAPS LOCK

key on a computer keyboard
cannot be used to print th
e special characters on the keys in the number row.





Keyboard Types

Keyboards are used primarily to enter alphanumeric data. Not surprisingly, keyboards for
oriental languages are significantly more complex than the keyboard shown in Figure 5
-
3. The
QW
ERTY keyboard was devised in 1867 by Christopher Sholes, inventor of the first practical
commercial typewriter. Ironically, Sholes’ intent when designing the keyboard was to slow
typists down; if typists worked too quickly, keys had a tendency to jam. Many

feel the
QWERTY keyboard is an anachronism, and its continued use is counterproductive. A more
recent design, called the Dvorak keyboard (named for August Dvorak, American educator, 1895
-
1975) places the most frequently used keys in the middle of the typi
ng area. Studies have shown
that trained typists using the Dvorak keyboard are up to 20 times faster than trained QWERTY
typists. Despite this, the Dvorak keyboard rarely is used. Repetitive stress injury (RSI) afflicts
more than 1.8 million people in the
United States. A debilitating repetitive stress injury that
plagues some keyboard users is carpal tunnel syndrome. This painful wrist injury affects
sufferers not only when working at the keyboard, but when performing other tasks as well. The
wrist rest on

the keyboard in Figure 5
-
3 is designed to reduce wrist strain.





Pointing Devices

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The original mouse was a one
-
button, cigarette
-
pack shaped device invented by Doug Engelbart
in 1964. Today, many software manufacturers have made the mouse (or a related

pointing
device) an essential part of their applications. When the screen is cluttered or pointer targets are
small, however, some experienced users still prefer keyboard commands if they are offered.

Some people feel that a touchpad is the most difficult

pointing device to use. To satisfy divergent
preferences, several laptop computers include
both

a pointing stick and a touchpad.

Although trackballs, touchpads, and pointing stick devices require less space than a mouse
(making them popular for portable c
omputers), most people find them harder to use. Because of
this a smaller mouse, called Mouse2Go, has been developed for use on a small pad that clips to
the side of a portable computer.

Joystick concepts evolved from actual use in jet fighter airplanes, w
here joysticks allowed pilots
to control an aircraft’s movement quickly and precisely.

Although touch screen users touch a symbol on the screen, it is the location where the touch
occurred, not the symbol contacted, that is important. Because they are so u
ser
-
friendly, even
people unfamiliar with computers are comfortable with touch screens.





Using a Mouse

The major advantage of a mouse is that it is easy to use. The disadvantages are twofold: first, the
mouse requires additional desk space, making it
difficult to use in cramped locations; and
second, mouse use demands that a hand be taken from the keyboard (unlike a pointing stick,
which can be used without removing a hand from the keyboard). When a mouse has two buttons,
one is the primary mouse butto
n and the other is the secondary mouse button. To reverse the
functions of these buttons or change other mouse options in Windows 98, point to Settings on the
Start menu, click Control Panel on the Settings submenu, then double
-
click the Mouse icon in
the
Control Panel window. In the Mouse Properties dialog box that displays, the Basics tab
allows you to change pointer speed, button selection, and double
-
click speed.





Mouse Types

Since its introduction in 1965, the mouse has gone through several transfo
rmations. Microsoft’s
“green eye” mouse, an early mouse with two buttons, was released in 1983 and now is a
collector’s item. Other interesting mouse variations include Spectrum’s RingMouse (which uses
infrared to point), Interlink’s wireless mouse (often
used for presentations), and Interlink’s
DuraPoint PC mouse (an incredibly durable mouse that gained the Pentagon’s interest). A new
mouse from Immersion Corporation provides tactile sensations, with an internal motor that
allows users to “feel” the deskto
p. The mouse


which senses cursor position, identifies screen
objects, and sends pulses to a motor beneath the surface of the mouse


lets users feel icons,
sense Web links, or bump through menu commands.

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Voice Recognition

Some experts believe voice
input eventually will be the most common way to operate a
computer. Speech recognition is particularly welcome to people with certain disabilities.
Although speech recognition continues to improve, developers admit that advertisements touting
high accuracy

rates generally assume a standard vocabulary. Specialized words, regional accents,
and local dialects reduce accuracy. Even a 95 percent accuracy rate, meaning that on average 1
out of every 20 words is wrong, may not inspire confidence. (Imagine if, in c
onversation, every
20
th

word spoken was misinterpreted.) Nevertheless, voice recognition systems are gaining in
popularity.





Handheld Computer Input

Instead of using a keyboard, with most handheld computers you write or make selections on the
computer
screen with a stylus. Although a handheld computer typically includes a basic stylus,
you can buy more elaborate models that have a ballpoint pen at one end and a stylus at the other.





Digital Cameras

Some manufacturers use dots per inch to represent a

digital camera’s resolution, or the sharpness
and clarity of the image it produces.
Dots per inch

(
DPI
) is the number of pixels in an inch of
screen display. A
pixel

is a single point in an electronic image. Digital cameras for the consumer
range from 640

x 480 dpi to 1,792 to 1,200 dpi. The actual photographed resolution is called the
optical resolution
. Some manufacturers also state
enhanced resolution
, which uses a special
formula to add pixels between those generated by the optical resolution. With the

price of digital
cameras decreasing, will the era of film
-
based cameras soon come to an end? Why or why not?





Video Input

Video input is used in a variety of ways, from developing training films to creating presentation
enhancements. Video input also
has been used in the workplace to record (sometimes secretly)
office or assembly
-
line workers in an effort to find possible quality or efficiency problems. Do
you think this secret recording is ethical? Why or why not?





PC Video Cameras and Web Cams

Es
timates suggest that currently more than 9,000 Web sites use Web cams. Web cams are used to
put everything from college dorm rooms to taxi cabs on the Web. The first personal Web page to
use a Web cam was the JenniCam, which showed the daily life of a coll
ege co
-
ed. The site
started in 1996 as a project for a computer class and still receives more than 4.5 million hits a
day. Web cams also have more practical uses. Recently, some day
-
care centers have installed
Web cams so parents can use the center’s Web p
age to check on their children. This use of Web
cams, however, has not been without controversy. Due to the usually slower speeds of Web cam
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videos, it can be difficult for parents to tell the difference between a day care worker’s loving pat
on the head a
nd a rap on the noggin.





Scanners and Reading Devices

In general, scanners and reading devices increase input accuracy and efficiency by reducing the
role of the weak link in the input process


the human operator. Optical readers are highly
specialized. Devices that read one set of codes, marks, or characters may not be able to read
another.

An optical mark reader identifies the position, not the shape, of a mark. You may be familiar
with optical marks from tests in which you use a pencil to
fill in ovals or rectangles that represent
the answers.

Bar codes minimize input errors, keep inventories up to date, help to track sales trends, and
eliminate the need to price individual items. The identifying numbers on a UPC code can be
entered if the
scanner fails. This number is
not

the item’s cost


prices are obtained from a
database when the item is scanned. Some consumer groups, however, claim price databases not
always are accurate, and that the absence of individual item pricing makes comparing
costs
difficult.

The MICR font, adopted by the American Banking Association in the 1950s, is standard
throughout the banking industry. The special shapes of MICR characters make them easier for a
machine to read. MICR readers can interpret magnetic charact
ers even if someone has written
over them. If the magnetic ink on a check is damaged, however, the data must be typed into the
system. The importance of MICR readers to the banking industry is staggering


half of the U.S.
population would be needed to pro
cess checks if it were done manually.





Input Devices for Physically Challenged Users

Some input aids for physically challenged people are relatively simple (such as keyguards),
while others are much more sophisticated (such as head
-
mounted pointers).
Chin
-
operated
joysticks also are available. Another input system, called Eyegaze or ERICA (Eyegaze Response
Interface Computer Aid), was developed by Thomas Hutchinson of the University of Virginia,
who as a boy was paralyzed temporarily by an accident. Wi
th a camera mounted on the computer
and directed at a user’s eye, the Eyegaze system can determine to within a ¼ inch where on the
screen a user is looking. By staring at the spot for about ¼ second, a user can activate a choice.
Adaptive technology has gi
ven many people their best opportunity to communicate, work, and
play. As a six
-
year
-
old victim of cerebral palsy said in her first message, “It’s about time.”



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Home

>
Notes

>
Discovering Computers

>
Chapter 6


|
Chapter 1

|
Chapter 2

|
Chapter 3

|
Chapter 4

|
Chapter 5

|
Chapter 6

|
Chapter 7

|
Chapter 8

|

Chapter 6: Output

|
Overview

|
Expand

Your Knowledge





Overview

1.

Define the four categories of
output

2.

Identify the different types of
display devices

3.

Describe factors that affect the
quality of a display device

4.

Identify monitor ergonomic
issues

5.

Explain the di
fferences among
various types of printers

6.

Describe the uses of speakers
and headsets

7.

Identify the purpose of data
projectors, fax machines, and
multifunction devices

8.

Explain how a terminal is both
an input and output device

9.

Identify output options for
physically challenged users

In
this chapter, you learn what is output and what are output devices. Display devices are
introduced, including CRT monitors, flat
-
panel displays, video cards, and high
-
definition
television. You explore monitor quality and monitor ergonomics. Various types
of printers are
presented, such as impact printers, nonimpact printers, portable printers, plotters and large
-
format printers, and special
-
purpose printers. You find out about audio output and other output
devices, including data projectors, facsimile mach
ines, and multifunction devices. Finally, you
become acquainted with terminals and output devices for physically challenged users.





Define the four categories of output

Output

is data that has been processed into a useful form called information. Four
types of
output are text, graphics, audio, and video.
Text

consists of characters (letters, numbers,
punctuation marks, or any other symbol requiring one byte of computer storage space) that are
used to create words, sentences, and paragraphs.
Graphics

are

digital representations of nontext
information such as drawings, charts, photographs, and animation (a series of still images in
rapid sequence that gives the illusion of motion).
Audio

is music, speech, or any other sound.
Video

consists of images played

back at speeds to provide the appearance of full motion. An
output device

is any computer component capable of conveying information to a user.

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Identify the different types of display devices

A
display device

is an output device that visually convey
s text, graphics, and video information.
Information shown on a display device is called
soft copy

because the information exists
electronically and is displayed for a temporary period of time. Display devices include CRT
monitors, LCD monitors and display
s, gas plasma monitors, and televisions. A
CRT monitor

is
a monitor that is similar to a standard television set because it contains a cathode ray tube. A
cathode ray tube

(
CRT
) is a large, sealed, glass tube. The front of the tube is a screen

coated
with phosphor material that glows as an electron beam moves back and forth, which produces an
image on the screen.
LCD monitors

and
LCD displays

use liquid crystal to present information
on the screen. A
liquid crystal display

(
LCD
) has liquid cryst
als between two sheets of
material. When an electric current passes through the crystals, they twist, causing some light
waves to be blocked and allowing others to pass through, which creates the images.

Similar to an LCD display, a
gas plasma monitor

is a
flat
-
panel display
. A gas plasma monitor,
however, substitutes a layer of gas for the liquid crystal material. When voltage is applied, the
gas releases ultraviolet light that causes
pixels

on the screen to glow and form an image. An
NTSC converter

c
onverts a computer’s digital signal into an analog signal that a standard
television set can display.
High
-
definition television

(
HDTV
) is a type of television set that
works with digital broadcasting signals and supports a wider screen and higher resoluti
on than a
standard television set.





Describe factors that affect the quality of a display device

The quality of a CRT monitor depends largely on its resolution, dot pitch, and refresh rate. The
quality of an LCD monitor or display depends primarily on

its resolution.

A CRT monitor’s screen is coated with tiny dots of phosphor material, called
pixels
, that glow
when electrically charged to produce an image.
Resolution
, which describes the sharpness and
clearness of that image, is related directly to the

number of pixels a monitor can display. The
greater the number of pixels the display uses, the better the quality of the image.
Dot pitch
, a
measure of image clarity, is the distance between each pixel on a display. The smaller the
distance between pixels

(dot pitch), the sharper the image.
Refresh rate

is the speed that a
monitor redraws images on the screen. Refresh rate should be fast enough to maintain a constant,
flicker
-
free image.

The resolution of an LCD monitor or display generally is proportional

to the size of the monitor
or display. That is, the resolution increases for larger monitors and devices.





Identify monitor ergonomic issues

The goal of ergonomics is to incorporate comfort, efficiency, and safety into the design of items
in the work
place. Features that address monitor ergonomic issues include controls to adjust the
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brightness, contrast, positioning, and height and width of images. Newer monitors have digital
controls that allow you to fine
-
tune the display. Many monitors also have a
tilt and swivel base
so the angle of the screen can be altered to minimize neck strain and glare. Monitors produce a
small amount of
electromagnetic radiation

(
EMR
), which is a magnetic field that travels at the
speed of light. High
-
quality monitors should

comply with
MPR II
, a standard that defines
acceptable levels of EMR for a monitor.





Explain the differences among various types of printers

A
printer

is an output device that produces text and graphics on a physical medium such as
paper or transpare
ncy film. Printed information is called
hard copy

because the information
exists physically and is a more permanent from of output. Printers can be grouped in two
categories: impact and nonimpact.

Impact printers

form characters and graphics by striking a
mechanism against an ink ribbon
that physically contacts the paper. A
dot
-
matrix printer

is an impact printer that prints images
when tiny wire pins on a print head mechanism strike an inked ribbon. A
line printer

is an
impact printer that prints an entire

line at one time. Two popular types of line printers are
band
printers

and
shuttle
-
matrix printers
.

Nonimpact printers

form characters and graphics without actually striking the paper. An
ink
-
jet printer

is a nonimpact printer that sprays drops of ink onto a piece of paper. A
laser printer

is a nonimpact printer that creates images using a laser beam and powdered ink, called
toner
. A
thermal printer

is a nonimpact printer that generates images by pushing
electrically heated pins
against heat
-
sensitive paper. Although the print quality of standard thermal printers generally is
low, two special types of thermal printers,
thermal wax
-
transfer printers

and
dye
-
sublimation
printers
, have a much higher print qua
lity.

Some printers are used for special purposes. A
photo printer

is a color printer that can produce
photo lab quality pictures as well as printing everyday documents. A
label printer

is a small
printer that prints on an adhesive type material that can b
e placed on a variety of items. A
portable printer

is a small, lightweight printer that allows a mobile user to print from a
notebook or handheld computer while traveling.
Plotters

are sophisticated printers used to
produce high
-
quality drawings such as bl
ueprints, maps, and circuit diagrams. A
large
-
format
printer
, which operates like an ink
-
jet printer but on a larger scale, creates photo
-
realistic quality
color prints.





Describe the uses of speakers and headsets

An
audio output device

produces music
, speech, or other sounds. Two commonly used audio
output devices are speakers and headsets. Most personal computers have an internal speaker that
outputs low
-
quality sound. Many users add high
-
quality stereo
speakers

or purchase PCs with
larger speakers b
uilt into the sides of the monitor. A
woofer

can be added to boost low bass
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sounds. A
headset