4
Software Basics
The Ghost in the
Machine
Chapter Outline
“All experience
shows
technological
changes
profoundly
transform
political and
social
relationships.”
John von Neumann
 2001 Prentice Hall
• Processing with Programs
• Software Applications: Tools for
Users
• System Software: The
Hardware-Software Connection
• The User Interface: The HumanMachine Connection
• Tomorrow’s User Interfaces
4.2
Processing with Programs
Software programs are:
– stored in memory
– a set of instructions that tell a
computer what to do
– designed to solve problems
 2001 Prentice Hall
4.3
Food for Thought
Suzanne’s French Toast Fantastique:
1.
Combine 2 slightly beaten eggs with 1 tsp
vanilla extract, ½ tsp cinnamon,  cup
milk
2. Dip 6 slices of bread in mixture
3. Fry in small amount of butter until golden
brown
4. Serve bread with maple syrup, sugar, or
tart jelly
 2001 Prentice Hall
4.4
A Fast, Stupid Machine
Computers:
– Have limited capabilities
– Can only do basic
mathematics and logical
comparisons
– Must be instructed with
programs what to do
 2001 Prentice Hall
4.5
The Language of Computers
• Programmers begin with an algorithm,
which is:
– A set of step-by-step instructions (written in a
natural language, e.g., English)
• Algorithms are ambiguous, error-prone
generalities
• Algorithms are translated into the
vocabulary of a programming language
 2001 Prentice Hall
4.6
Programming Languages
Bridge the gap
Human language
Numeric code
COBOL, BASIC, and C++
 2001 Prentice Hall
4.7
Software Applications:
Tools for Users
Software applications include:
– Consumer software
– Integrated software
– Vertical-market and custom software
 2001 Prentice Hall
4.8
Consumer Applications
• Consumer software differs from other
types (music CDs, videos, etc.) based on:
– Documentation
– Upgrade options
– Compatibility
– Warranty
– Extent of ownership/license
 2001 Prentice Hall
4.9
Documentation
Documentation includes:
– Printed tutorial and reference manuals
that explain how to use the software
– On-line manuals and help screens which
offer immediate help to the user
 2001 Prentice Hall
4.10
Upgrades
• Upgrades allow you to pay a fee to get
the latest software version
• Newer releases often have additional
features and fewer bugs
 2001 Prentice Hall
4.11
Compatibility
• Compatibility allows
software to
function properly
with the hardware,
operating system,
and peripherals
 2001 Prentice Hall
• Programs written
for one type of
computer system
may not work on
another
4.12
Warranty
Buyer Beware!
• Software manufacturers limit their
liability for software problems by
selling their software “as is”
• Error-free software does not exist
 2001 Prentice Hall
4.13
Ownership/Licensing
• Three categories:
– Purchased software grants you a license to use
the software as the software company tells you
– Shareware software is free for the trying, but
a nominal fee is to be paid to the programmer if
you continue to use it
– Public domain software is legally free and
cannot be owned or licensed
 2001 Prentice Hall
4.14
Integrated Applications and Suites:
Software Bundles
• Multipurpose software includes most
of these modules:
– Word processing
– Database
– Spreadsheet
– Graphics
– Telecommunications
 2001 Prentice Hall
4.15
Integrated Software:
Advantages
• Costs less than buying the
applications individually
• Data is easily transferred
between modules
• Commands used in each
module are usually the same
• Usually there is a seamless
integration of the modules
 2001 Prentice Hall
4.16
Vertical-Market and
Custom Software
• Job-specific software:
- Medical billings
- Library cataloging
- Restaurant management
- Single-client software needs
 2001 Prentice Hall
4.17
What the Operating System Does
• The operating system controls:
– Communication with peripherals
– Coordination of concurrent processing
– Memory management
– Monitoring of resources and security
– Management of programs and data
– Coordinating network communications
 2001 Prentice Hall
4.18
Utility Programs
Utility software controls tasks such as:
– repairing damaged files
– making it easy for users to copy files
from one storage device to another
– translating files so different
software can read them
– guarding against viruses
 2001 Prentice Hall
4.19
Where the Operating System Lives
• Some computers store
their operating system in
ROM
• Others include only part
of it in ROM
– The remaining system is
loaded into memory
(booting)
• Most of the time it
works behind the scenes
 2001 Prentice Hall
4.20
The User Interface:
The Human-Machine Connection
The user interface is what
the user sees on the screen
Two major user interface types:
– Character-based interface
– Graphical user interface (GUI)
 2001 Prentice Hall
4.21
A Character-Based Interface:
MS-DOS
• This is a disk operating system in
which the user interacts using
characters
– letters
– numbers
– symbols
 2001 Prentice Hall
4.22
A Character-Based User Interface:
MS-DOS
• MS-DOS™ is the most widely used
general-purpose operating system
• Features include:
– Command-line interface (commands are
typed)
– Menu-driven interface (commands are
chosen from on-screen lists)
 2001 Prentice Hall
4.23
Graphical User Interfaces:
Macintosh
• This is a disk operating system in which
the user interacts with the computer
by using a pointing device (e.g. a mouse)
• As early as 1984, the
Macintosh™ computer
was designed with this
interface in mind
 2001 Prentice Hall
4.24
Graphical User Interfaces:
Windows
• Windows 95
and 98 are
similar in many
ways to the
Mac OS
• Several versions of
Windows exist for
business and home
users
 2001 Prentice Hall
4.25
Why WIMP Won
Windows, Icons, Menus, and
Pointing devices
• They’re intuitive
• They’re consistent
• They’re forgiving
• They’re protective
• They’re flexible
 2001 Prentice Hall
4.26
Multiple User Operating Systems:
UNIX and Linux
• UNIX was developed at Bell Labs
before personal computers were
available
• Linux was created by Linus Torvalds
and continues to be a work-in-progress
– Linux is free for anyone to use or improve
 2001 Prentice Hall
4.27
Multiple User Operating Systems:
UNIX and Linux
• UNIX remains a dominant Internet
operating system for Internet servers.
• These systems allow a timesharing
computer to communicate with
several other computers or terminals
at once.
 2001 Prentice Hall
4.28
Hardware & Software Platforms
• Windows 9x(ME)
• IBM’s OS/2
• Windows 2000
• Mac OS/9
• Windows CE
• Mac OS/X
• Palm OS
• UNIX & Linux
• BeOS
 2001 Prentice Hall
4.29
Rules of Thumb
Consumer Concepts
Before you buy:
– Determine what you
can afford
– Allow for “extras”
– Join a user group or
talk with other computer
and software owners
 2001 Prentice Hall
4.30
Rules of Thumb:
Consumer Concepts
Consider:
• What kind of tasks you
will be doing
• If the processor can
handle your demands
• If your computer can
be customized to fit
your needs (such as
video editing)
• If you will be able to
upgrade
• How much computer
power you need
 2001 Prentice Hall
4.31
Rules of Thumb:
Consumer Concepts
Consider:
• If you need a highspeed modem or
network connection
• If you should have the
same machine as those
you work with
• Whether portability or
permanent connection of
peripherals is important
• If you are buying from a
reputable company
• Which kind of user
interface will help you
do your work easier
 2001 Prentice Hall
• What kind of support is
available
4.32
Tomorrow’s User Interfaces
Future interfaces will probably:
– Make individual applications
obsolete
– Support natural languages
(talk to the machine and it
talks back)
– Include artificial intelligence
and agents that fit our needs
– Be based on virtual reality
(data in three-dimensional
physical space)
 2001 Prentice Hall
4.33