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Lesson 4: What Is Software?
Computer Literacy
BASICS
Objectives
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Distinguish between software and
hardware.
Explain how a computer software
program works.
Understand the steps involved in
software development.
Describe the difference between
applications software and systems
software.
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Objectives (cont.)
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Describe the three categories of
systems programs.
Describe operating systems for
microcomputers, including network
operating systems.
Define a user interface.
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Objectives (cont.)
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Explain the difference between a
command-line user interface and a
graphical user interface.
Understand the boot process a
computer goes through when you start
it.
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Vocabulary
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Algorithm
Applications software
Boot
Graphical user
interfaces (GUIs)
Language translators
MS-DOS
Multitasking
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Network operating
system
Operating systems
Software
development
Systems software
Unix
User interface
Utility software
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Hardware vs. Software
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Computer systems consist of both
hardware and software.
Hardware has little value without
software, and software cannot run
without hardware to run it.
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What Is Hardware?
Hardware refers to anything you can
physically touch:
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The keyboard and the mouse
The monitor and the printer
The motherboard and expansion cards
All the other components in the computer
case or attached to the computer
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What Is Software?
Software consists of the instructions
issued to the computer to perform
specific tasks:
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The software on a computer system
refers to the programs that make the
computer run.
Software programs are lists of
instructions in code that the computer
understands that tell the computer what
to do.
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How Software Programs Work
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A computer processes data by
applying rules called algorithms.
An algorithm creates a logical
progression of steps needed to
accomplish a task.
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An Algorithm to Solve a Household
Problem: Dirty Laundry
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Software Development
Software development is a multistep process
that begins with a need to perform a task
more efficiently using a computer:
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First, the programmer breaks down the
problem into a series of steps in an algorithm.
The programmer may use a flowchart to show
different paths the program will take.
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Software Development (cont.)
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Next, the programmer writes the steps
in a computer programming language
or code, using formal terms and
syntax.
Then the computer translates the code
into machine language it can
understand and uses the translated
commands to execute a program.
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Debugging Software
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The software development process does not
end when the computer executes the
program.
Errors in syntax or even spelling can cause
problems and distort program results.
Tests of the software find and fix “bugs” or
errors in the code so it will run properly.
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Types of Software
There are literally thousands of software
programs you can buy, but all of them
can be grouped into one of two
categories:
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Applications software
Systems software
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Applications Software
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Application software consists of
programs that were created to perform
a specific task.
Application software is also called
productivity software.
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Applications Software (cont.)
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The most common types of application
software are
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Word-processing programs
Spreadsheet software
Presentation software
Database software
Web browsers
Games
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Systems Software
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Systems software refers to the programs that are
used to manage computer system resources.
Systems software coordinates and controls the
resources and operations of the computer itself.
The three categories of systems software are
 Operating systems
 Utility programs
 Language translators
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Operating Systems
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Operating systems provide an
interface between the user and the
computer.
There are many brands and versions
of operating systems.
An operating system is designed to
work with a specific processor.
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An Operating System Is an Interface
Between Users and Computers
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Utility Programs
Utility programs are designed to help perform
housekeeping chores for the computer:
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Manage the computer’s resources
Perform file and folder management tasks
Clean up unused files from the hard disk
Defragment disk storage
Copy files from one disk to another
Back up data to disk or tape
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Language Translators
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Computers cannot read program statements
in programming language format, such as
Visual Basic or Java program statements.
Language translator programs convert
program language code into machine code
that can be understood by the computer.
Once converted to machine code, the
program can be run and executed by the
computer.
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Microcomputer Operating
Systems
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If your computer is a Macintosh, you
are probably using a Mac OS.
If your computer is a PC or is PC
compatible, you are most likely using
one of these operating systems:
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DOS
A combination of DOS and Windows
A standalone version of Windows
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Mac OS
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Macintosh computers were introduced
by Apple Computer in 1984.
Macintosh had one of the first GUI
operating systems, with icons that
represented programs, documents,
and disks.
This was also the first operating
system to provide an on-screen help
system.
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DOS
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IBM introduced its first PC in 1981. Its operating
system was called DOS, which stands for Disk
Operating System.
DOS is a command-line interface operating
system. The user had to enter commands at a
screen prompt.
It was a single-tasking operating system, which
meant that only one program at a time could be
executed.
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Windows
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Windows was Microsoft’s first GUI
operating system, released in 1987.
The first versions were called
operating environments because they
acted as a shell around the DOS
operating system and worked in
combination with DOS.
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Windows
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Applications installed on a Windows
system appeared as icons that were
activated by clicking them, similar to the
Mac OS Finder interface.
The earliest versions of Windows were
labeled Windows 3.0, 3.1, and so on.
The first true multitasking version of
Windows was Windows 95, which also
included support for networking
computers.
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Windows
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Windows 98 improved on Windows 95 and
offered Internet integration and support for the
USB bus.
Windows 2000 was an update to Windows 98
and Windows NT and included tools for Web
site creation.
The latest version is Windows XP, which
provides increased stability and device
recognition.
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The Windows XP Operating
System
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Other Operating Systems
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Unix was developed by AT&T and is
another early operating system that is
still used today.
It is a portable operating system, which
means it can run on any hardware
platform.
Variants of Unix include the freeware
operating system Linux and IBM’s AIX.
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Network Operating Systems
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A network operating system (NOS) is
designed to allow multiple computers
to be connected and talk to each other.
The most popular networking
operating systems include
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Microsoft Windows NT
Novell’s Netware
IBM’s Warp Server
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User Interfaces
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You are probably familiar with the user
interface of an operating system because it
is what you see when you use the computer.
The user interface determines how “user
friendly” the operating system is.
There are two commonly used types of
operating system interfaces, command-line
interfaces and graphical user interfaces.
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Command-Line Interfaces
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With this interface, you must type
exact commands into the computer
from a command prompt.
You must memorize many commands
and keywords.
Command-line interfaces are not as
user friendly as graphical user
interfaces.
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Graphical User Interfaces
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Menu-based interfaces were easier to
use, providing options so that
commands did not need to be
memorized.
The breakthrough in ease of use came
with the introduction of graphical user
interfaces (GUIs).
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Graphical User Interfaces
(cont.)
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Users manipulate on-screen icons to
perform functions, usually with a
mouse or other pointing device.
Most of today’s personal computers
are equipped with some type of userfriendly GUI.
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Comparing User Interfaces
Command-Line Interface
Command
prompt
Icons
representing
programs or files
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Graphical
User Interface
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Starting Your Computer
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When you start your computer, operating system
commands are loaded into memory.
Each operating system starts the computer in its
own individual way.
When you turn on a computer, you boot the
system.
POST (Power-on Self Test), a series of tests that
check RAM and verify that the keyboard and disk
drives are connected to the computer, runs when
you start your computer.
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Starting Your Computer (cont.)
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Then the BIOS (Basic Input Output System)
searches for the boot record. The hard disk
drive C is typically the startup drive, so that
is where the BIOS will look first for the boot
record. BIOS is built-in software on a ROM
chip. It contains all of the code that controls
the monitor, keyboard, disk drives, and other
components.
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Starting Your Computer (cont.)
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The boot record, which includes several files, is
loaded into RAM. These files contain
programming configuration instructions for
hardware devices and software applications that
you may have installed on your computer.
Next, the software drivers are loaded. Drivers
enable you to use your printer, modem, scanner,
or other devices. Generally, when you add a new
device to your system, drivers are installed for
that device.
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Starting Your Computer (cont.)
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Next to be loaded is the GUI or graphical user
interface, such as Windows XP. When loading
the GUI, the operating system reads the
commands for your desktop configuration. It
also loads whatever programs you have
previously specified into the Windows Startup
Folder.
If everything goes as it should, the GUI displays
the desktop and the computer is ready to use.
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Summary
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Hardware refers to anything you can
touch.
Software is instructions that tell the
computer what to do.
Software is also called a program.
A computer processes data by
applying rules called algorithms.
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Summary (cont.)
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An algorithm creates a logical progression
of steps needed to accomplish a task.
Software development is a multistep
process that includes writing the command
code in a programming language, having
the computer translate the code into
machine language, and then debugging and
testing the program.
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Summary (cont.)
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The two basic types of computer software are
applications software, also called productivity
software, and systems software.
Systems software coordinates and controls the
resources and operations of a computer
system.
Three major categories of systems software are
operating systems, utilities, and language
translators.
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Summary (cont.)
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Operating systems provide an interface
between the user and application program
and the computer hardware.
Utility programs help users complete
specialized tasks, such as file management.
Language translators convert code written in
English-based software programs into
machine language.
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Summary (cont.)
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All computers have operating systems.
Mac OS is used with Apple’s Power
Macintosh computers and Power
Macintosh clones.
DOS was introduced with the IBM PC
in 1981 and is a character-based
operating system.
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Summary (cont.)
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Microsoft introduced the first version of
Windows in 1987; this was an
operating environment.
Windows 95 was Microsoft’s first true
multitasking operating system.
Unix is a portable operating system.
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Summary (cont.)
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Network operating systems allow a group of
two or more microcomputers to be
connected.
The user interface is the part of the
operating system with which we are most
familiar.
The two most common user interfaces are
command-line interfaces and graphical user
interfaces.
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Summary (cont.)
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Most of today’s computers come with some
type of graphical user interface.
Icons are symbols that represent
documents, software programs, disks, and
so forth.
A graphical interface includes standard text
and graphics so that data processed in one
application program can be shared by other
applications.
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