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Chapter 4
Software Basics:
The Ghost in the Machine
 2002 Prentice Hall
Topics
Processing with Programs
Software Applications: Tools for Users
System Software: The Hardware-Software Connection
The User Interface: The Human-Machine Connection
Tomorrow’s User Interfaces
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Processing with Programs
Software programs are:
Stored in memory
Instructions that tell the computer what to do
Designed to solve problems
Leonardo da Vinci called music ”the shaping of the invisible,“
and his phrase is even more apt as a description of software.
—Alan Kay, developer of the concept of the personal computer
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Food for Thought
Suzanne’s French Toast Fantastique:
1.
2.
3.
4.
Combine 2 slightly beaten eggs with 1 tsp vanilla
extract, ½ tsp cinnamon, 1 cup milk
Dip 6 slices of bread in mixture
Fry in small amount of butter until golden brown
Serve bread with maple syrup, sugar, or tart jelly
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A Fast, Stupid Machine
Computers:
Perform arithmetic and comparisons capabilities
Follow precise instructions to perform an operation
Execute instructions quickly and accurately
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A Fast, Stupid Machine
Programmers begin with an algorithm
An algorithm 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
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The Language of Computers
Machine Language numeric codes to represent data
High-level language fall between machine
language and natural human language
Compilers translates high-level language into
Natural Languages include the languages spoken
by humans
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Software Applications:
Tools for Users
Software applications include:
Consumer Applications
Integrated Software
Vertical-market
Custom Software
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Consumer Applications
• Consumer software differs from other types (music
CDs, videos, etc.) based on:
 Documentation
 Upgrade options
 Compatibility
 Warranty
 Extent of ownership/license
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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
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Upgrades
Upgrades allow you to pay a fee to get the latest
software version
Newer releases often have additional features and
fewer bugs
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Compatibility
Compatibility allows
software to function
properly with the
hardware, operating
system, and peripherals
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Programs written for one
type of computer system
may not work on another
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Disclaimers
Software manufacturers limit their liability for
software problems by selling software “as is”
Given the difficulty of this task, most programs
work amazingly well—but not perfectly
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Licensing
Licensing agreements limit your right to:
 Make copies of software disks
 install software on hard drives
 transfer information to other users
Commercial software is copyrighted so it can’t be
legally duplicated for distribution to others.
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Distribution
Software is distributed through direct sales forces
to corporations and other institutions.
Software is sold to consumers through:
 retail stores
 mail-order catalogs
 Web sites.
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Integrated Applications and
Suites: Software Bundles
Multipurpose software includes most of these
modules:
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Word processing
Database
Spreadsheet
Graphics
Telecommunications
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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
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Vertical-Market and
Custom Software
Job-specific software:
 Medical billings
 Library cataloging
 Restaurant management
 Single-client software needs
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System Software: The HardwareSoftware Connection
System software is a class of software that
includes:
 The operating system
 Utility programs
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What the Operating System Does
The operating system controls:
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Communication with peripherals
Coordination of concurrent processing
Memory management
Monitoring of resources and security
Management of programs and data
Coordinating network communications
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Utility Programs
Upgrades allow you to pay a fee to get the latest
software version
 repairing damaged files
 copying files from one
storage device to another
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 translating files so different
software can read them
 guarding against viruses
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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
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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)
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A Character-Based Interface:
MS-DOS
This is a disk operating system in which the user
interacts using characters
 letters
 numbers
 symbols
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A Character-Based Interface:
MS-DOS
MS-DOS™ is the most widely used generalpurpose operating system
Features include:
 Command-line interface (commands are typed)
 Menu-driven interface (commands are chosen from
on-screen lists)
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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
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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
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Why WIMP Won
Windows, Icons, Menus, and Pointing devices
• They’re intuitive
• They’re consistent
• They’re forgiving
• They’re protective
• They’re flexible
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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
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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.
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Hardware & Software Platforms
Windows XP
IBM’s OS/2
Windows ME
Mac OS/9
Windows 2000
Mac OS/X
Windows CE
Linux & UNIX
Palm OS
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Tomorrow’s User Interfaces
Future interfaces will probably:
 Make individual applications obsolete
 Include more network applications
 Support natural language interfaces such
as talking to the machine
 Include artificial intelligence and agents
 Be based on virtual reality
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