INTRODUCTION TO THE WORLD OF COMPUTERS
Outline Users and Computer Professionals
Computer Networks and the Internet
Overview The Internet
Computers in Your Life Accessing Networks
Why Learn About Computers? Network Servers
Computers in the Home Computer Systems to Fit Every Need
Computers in the Workplace Mobile Devices
Computers in our Society Personal Computers
What Is a Computer and What Does It Do? Sizes of PC Systems
Traditional and Multimedia Hardware Network Computers, Thin Clients, and
Input Devices Internet Appliances
Processing Devices PC Compatible or Macintosh?
Output Devices Midrange Computers
Storage Devices Mainframe Computers
Application Software Computers and Society
Systems Software The Information Age and the New Information
Data, Information, and Programs Revolution
Benefits of a Computer-Oriented Society
Data Impact of Computers, the Internet, and a Networked
Application software. Programs that enable users to perform specific tasks on a computer.
Central processing unit (CPU). The chip located inside the system unit of a computer that
performs processing and communicates with peripheral devices.
Computer. A programmable, electronic device that accepts data input, performs operations on that
data, and presents and stores the results.
Computer network. A collection of computers and devices that are connected together to share
hardware, software, and data, as well as to electronically communicate with one another.
Data. Raw, unorganized facts.
Hardware. Physical equipment in a computer system, such as the computer and its peripheral
Information. Data that has been processed into a meaningful form.
Input. What is supplied to a computer for processing.
Internet. The largest and most widely used computer network in the world, linking millions of
computers all over the world.
Internet appliance. A specialized network computer designed primarily for Internet access and e-
Macintosh. A type of personal computer manufactured by Apple.
Mainframe computer. A large computer that performs extensive business transaction processing.
Memory. A temporary holding place for the computer to store data and program instructions
awaiting processing, intermediate results, and processed output.
Microcomputer. A computer system based on a microprocessor, designed to be used by one
person at a time.
Midrange computer. An intermediate-sized and medium-priced computer.
Mobile device. A very small device, usually based on a wireless phone or pager, that can perform a
limited amount of computing.
Network computer (NC). A PC designed to access a network for processing and data storage,
instead of performing those tasks locally.
Output. The results of computer processing.
PC compatible. A personal computer based on Intel microcomputer or compatible CPUs.
Personal computer (PC). Another name for microcomputer.
Processing. The conversion of input to output.
Program. A set of instructions that tells a computer system to perform specific actions.
Programmer. A person whose job it is to write, maintain, and test computer programs.
Software. Computer programs.
Storage. Saving data, results, or programs for future use.
Supercomputer. The fastest, most expensive, and most powerful type of computer.
Systems software. Programs, such as the operating system, that control the operation of a
computer and its devices, as well as enable application programs to run on a computer system.
Thin client. Another name for network computer.
User. A person who uses a computer system.
Computers in Your Life
We are living in the midst of a computer revolution, where most skill-based jobs heavily
depend on the creation, collection, and dissemination of information.
Computers are also prevalent in the home, as well as in our society in general.
Consequentially, virtually everyone should have some experience with, and a basic level of
comfort with, computers.
What Is a Computer and What Does It Do?
A computer is a programmable electronic device that accepts input, performs processing on
that input, outputs the results, and can store the program, data, or output as needed.
These terms can be clarified by considering a typical home stereo system. The system normally
has a CD player that inputs signals to a receiver. The receiver processes the signals and then
passes them on as output to the speakers. The CDs that you insert into the CD player store
The CD player and speakers are peripheral equipment in the stereo system. Specifically, the
CD player is an input device and the speakers are output devices.
The CDs or DVDs that you have in your music collection are—in computer terms—storage
media. They store music in a machine-readable form—a form the associated input device can
recognize and convert into signals for the receiver to process.
All the elements in a stereo system have their counterparts in a computer system. At a
minimum, a computer system consists of the computer itself and its peripheral equipment. Also
often included are the programs and data being processed, as well as operating manuals,
procedures, and the people who use the system. In other words, all the components that
contribute to making the computer a useful tool can be said to be part of a computer system.
Most computers today are multimedia computer systems, which contain special hardware for
use with sound and video, such as speakers, a microphone, or a video camera.
At the heart of any computer system—equivalent to the stereo receiver—is the central
processing unit (CPU). Like a stereo receiver, the computer can’t do anything useful without
support equipment for input and output, and I/O media for storage. Other devices are included
for input, output, and storage.
While most types of computer storage are nonvolatile, a computer utilizes volatile memory to
temporarily store programs and input while it is being processed. A stereo receiver has no
memory—what’s playing on the CD player passes directly through the receiver to the speakers.
Because a computer can store materials in its memory, it can be directed to rearrange or
recombine those materials in an amazing variety of ways before it sends them along as output.
Software refers to the programs or instructions used to tell the computer hardware what to do.
Software can be purchased in physical packages or downloaded from the Internet.
Most software is revised periodically and new versions released.
Application software is used to perform specific tasks or applications; systems software
allows a computer to operate and run application software.
Data, Information, and Programs
Data is essentially raw, unorganized facts. It can be in the form of text, graphics, audio, or
Information refers to data that has been processed into a useful form.
Programs are instructions that tell the computer how to process data to produce the results you
want. Programs are written in a programming language, such as Visual Basic, C++, Java, or
Users and Computer Professionals
Users, or end users, are the people in the computing environment who need the output that
computer systems produce.
Programmers are the people whose job it is to write programs to supply this information.
There may also be other computer professionals in an organization, such as to determine the
company’s processing needs, to train users, or to operate, repair, or maintain the company’s
Computer Networks and the Internet
A computer network ties users together to share hardware, software, and data, as well as to
electronically communicate with each other.
Computer networks exist in many sizes and types. Many utilize a network server to run the
network and host shared programs and data.
The Internet is the largest computer network in the world, connecting millions of PCs and
thousands of computer networks together. Two of the most common Internet activities are
accessing information on the World Wide Web (a huge collection of Web pages) and
To access a computer network, you need a modem or some other kind of network adapter to
physically connect your computer to the network. You also need a software program to let you
connect to and use the facilities of a network.
Computer users often hear the terms online and offline with reference to computer networks
and in various other contexts. Any computer in a state that allows it to send data to or receive
data from a computer network or other device is said to be online to the network or device. If a
device isn’t online, it’s offline.
Computer Systems to Fit Every Need
Computers are generally classified in one of four categories: small, or “microcomputers”;
medium-sized, or “midrange computers”; large, or “mainframe computers”; and super-large, or
“supercomputers.” An emerging new category is “mobile devices,” as discussed next. In
practice, however, the distinction among these different sizes is not always clear-cut. Large
midrange computers, for example, are often bigger than small mainframes.
In general, the larger the computer, the greater its processing power. For example, big
computers can process data at faster speeds and can perform more complicated types of
processing than can small computers. Big computers can also accommodate larger, more
powerful support devices.
A mobile device is loosely defined as a very small computing device based on a wireless
phone or pager. Such devices usually offer limited Internet access in addition to their regular
functions, such as placing phone calls and sending and receiving pages or messages.
Most mobile devices don’t utilize a keyboard, so a voice-based interface is likely to become
more common as the Internet capabilities of these devices increase.
A technological breakthrough in the early 1970s made it possible to produce an entire CPU on
a single silicon chip smaller than a dime. These “computers-on-a-chip,” or microprocessors,
can be mass-produced at a very low cost.
Microprocessors also made it possible to build inexpensive computer systems small enough to
fit on a desk or your lap. The small computers at the heart of these systems have come to be
called microcomputers or personal computers (PCs).
Although most microcomputers designed for home or business use are desktop computers,
smaller PCs are available. Portable PCs include notebook, tablet, handheld, and pocket
PCs designed for network use only are referred to as network computers or thin clients. PCs
or devices designed for Internet access only are called Internet appliances.
Most PC users choose between two major computer platforms when they buy a computer—PC
compatibles and Macintosh computers. Often, people refer to PC-compatible computers as the
Windows platform or as IBM-compatible PCs.
Midrange computers (or minicomputers) are generally regarded as medium-sized computers.
Most of them fall between microcomputers and mainframes in their processing power.
Any of several factors might lead an organization to choose a midrange computer over a PC or
mainframe. A small or medium-sized company, for example, may find a microcomputer system
just too small or too slow to handle its current volume of work.
The mainframe is the mainstay of almost all large organizations; it specializes in high-volume
processing of business transactions.
Mainframes often operate 24 hours a day, serving dozens of users on terminals during regular
business hours and processing big jobs such as payroll and billing late at night.
Some organizations, such as large scientific research laboratories, have extraordinary demands
for processing power.
To meet applications needs such as very fast speeds and extreme degrees of accuracy, a few
vendors offer very powerful computers, called supercomputers.
Many supercomputers today are created by linking together multiple PCs or microprocessor
Computers and Society
Computers are indispensable in a society such as ours. Without computers, for example, the
government would be hard pressed to tabulate census data, banks could not process financial
transactions quickly, and space exploration would be impossible.
The prominence of information technology has been referred to as the information age. Today,
many believe we are entering into a new information revolution.
There are many benefits of a computer-oriented society. Day-to-day operations of many
individuals are immensely affected by computers.
But along with the benefits computers bring to society have come some troubling problems.
Health and privacy concerns are among the most talked about.