Think about some of the different ways that people use computers. In school, students use computers
for tasks such as writing papers, searching for articles, sending email, and participating in
online classes. At work, people use computers to analyze data, make presentations, conduct business
transactions, communicate with customers and coworkers, control machines in manufacturing
facilities, and do many other things. At home, people use computers for tasks such as paying
bills, shopping online, communicating with friends and family, and playing computer games.
And don’t forget that cell phones, iPods®, BlackBerries®, car navigation systems, and many
other devices are computers too. The uses of computers are almost limitless in our everyday lives.
Computers can do such a wide variety of things because they can be programmed. This means
that computers are not designed to do just one job, but to do any job that their programs tell
them to do. A program is a set of instructions that a computer follows to perform a task. For
example, Microsoft Word and
Adobe Photoshop. Microsoft Word is a word processing program that allows you to create,
edit, and print documents with your computer. Adobe Photoshop is an image editing program
that allows you to work with graphic images, such as photos taken with your digital camera.
Programs are commonly referred to as software. Software is essential to a computer because
it controls everything the computer does. All of the software that we use to make our computers
useful is created by individuals working as programmers or software developers. A
programmer, or software developer, is a person with the training and skills necessary to
design, create, and test computer programs. Computer programming is an exciting and
rewarding career. Today, you will find programmers’ work used in business, medicine, government,
law enforcement, agriculture, academics, entertainment, and many other fields.
Topic of Discussion
Hardware and Software
The physical devices that a computer is made of are referred to as the
computer’s hardware. The programs that run on a computer are referred
to as software.
Hardware
The term hardware refers to all of the physical devices, or components, that a computer is made
of. A computer is not one single device, but a system of devices that all work together. Like the
different instruments in a symphony orchestra, each device in a computer plays its own part.
If you have ever shopped for a computer, you’ve probably seen sales literature listing components
such as microprocessors, memory, disk drives, video displays, graphics cards, and
so on. Unless you already know a lot about computers, or at least have a friend that does,
understanding what these different components do might be challenging.A typical computer system consists
of the following major components:
Software
If a computer is to function, software is not optional. Everything that a computer does,
from the time you turn the power switch on until you shut the system down, is under the
control of software. There are two general categories of software: system software and
application software. Most computer programs clearly fit into one of these two categories.
Let’s take a closer look at each.
System Software
The programs that control and manage the basic operations of a computer are generally
referred to as system software. System software typically includes the following types of
programs:
Operating Systems An operating system is the most fundamental set of programs on a
computer. The operating system controls the internal operations of the computer’s
hardware, manages all of the devices connected to the computer, allows data to be saved
to and retrieved from storage devices, and allows other programs to run on the computer.
Figure 1-6 shows screens from three popular operating systems: Windows Vista, Mac OS
X, and Linux.
M01_GADD7119_01_SE_C01.QXD 1/23/08 5:19 PM Page 6
1.2 Hardware and Software 7
Figure 1-6 Screens from the Windows Vista, Mac OS X, and Fedora Linux operating systems
Windows Vista Mac OS X
Fedora Linux
Utility Programs A utility program performs a specialized task that enhances the computer’s
operation or safeguards data. Examples of utility programs are virus scanners,
file compression programs, and data backup programs.
Software Development Tools Software development tools are the programs that programmers
use to create, modify, and test software. Assemblers, compilers, and interpreters
are examples of programs that fall into this category.
Application Software
Programs that make a computer useful for everyday tasks are known as application software.
These are the programs that people normally spend most of their time running on
their computers. Figure 1-1, at the beginning of this chapter, shows screens from two
commonly used applications: Microsoft Word, a word processing program, and Adobe
Photoshop, an image editing program. Some other examples of application software are
spreadsheet programs, email programs, web browsers, and game programs.
Programming Languages
Language Description
Ada Ada was created in the 1970s, primarily for applications used by the U.S.
Department of Defense. The language is named in honor of Countess Ada
Lovelace, an influential and historic figure in the field of computing.
BASIC Beginners All-purpose Symbolic Instruction Code is a general-purpose language
that was originally designed in the early 1960s to be simple enough for beginners
to learn. Today, there are many different versions of BASIC.
FORTRAN FORmula TRANslator was the first high-level programming language. It was
designed in the 1950s for performing complex mathematical calculations.
COBOL Common Business-Oriented Language was created in the 1950s, and was
designed for business applications.
Pascal Pascal was created in 1970, and was originally designed for teaching programming.
The language was named in honor of the mathematician, physicist, and
philosopher Blaise Pascal.
C and C++ C and C++ (pronounced “c plus plus”) are powerful, general-purpose languages
developed at Bell Laboratories. The C language was created in 1972
and the C++ language was created in 1983.
C# Pronounced “c sharp.” This language was created by Microsoft around the
year 2000 for developing applications based on the Microsoft .NET platform.
Java Java was created by Sun Microsystems in the early 1990s. It can be used to develop
programs that run on a single computer or over the Internet from a web server.
JavaScript JavaScript, created in the 1990s, can be used in web pages. Despite its name,
JavaScript is not related to Java.
Python Python, the language we use in this book, is a general-purpose language created
in the early 1990s. It has become popular in business and academic applications.
Ruby Ruby is a general-purpose language that was created in the 1990s. It is increasingly
becoming a popular language for programs that run on web servers.
Visual Basic Visual Basic (commonly known as VB) is a Microsoft programming language and
software development environment that allows programmers to create Windowsbased
applications quickly. VB was originally created in the early 1990s.
M01_GADD7119_01_SE_C01.QXD 1/23/08 5:19 PM Page 17
18 Chapter 1 Introduction to Computers and Programming
Table 1-2 The Python key words
and del from not while
as elif global or with
assert else if pass yiel
break except import print
class exec in raise
continue finally is return
def for lambda try
Key Words, Operators, and Syntax: an Overview
Each high-level language has its own set of predefined words that the programmer must
use to write a program. The words that make up a high-level programming language are
known as key words or reserved words. Each key word has a specific meaning, and cannot
be used for any other purpose.
Post a Comment