Software Basics: The Ghost in the Machine
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Transcript of Software Basics: The Ghost in the Machine
2002 Prentice Hall
Software Basics
Software Basics:
The Ghost in the Machine
2002 Prentice Hall 2
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
2002 Prentice Hall 3
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
1. Combine 2 slightly beaten eggs with 1 tsp vanilla extract, ½ tsp cinnamon, 1 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
Suzanne’s French Toast Fantastique:
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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
Compliers 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 allow you to pay a fee to get the latest software version
Newer releases often have additional features and fewer bugs
Upgrades
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Compatibility
Compatibility allows software to function properly with the hardware, operating system, and peripherals
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 BundlesMultipurpose software includes most of these modules: 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 andCustom Software
Job-specific software: Medical billings Library cataloging
Restaurant management Single-client software needs
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System Software:The Hardware-Software
ConnectionSystem 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: 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
translating files so different software can read them
guarding against viruses
repairing damaged files copying files from one
storage device to another
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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 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)
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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™ computerwas 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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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.
Multiple User Operating Systems: UNIX and Linux
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Hardware & Software Platforms
Windows XP
Windows ME
Windows 2000
Windows CE
Palm OS
IBM’s OS/2
Mac OS/9
Mac OS/X
Linux & UNIX
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Tomorrow’s User Interfaces
Make individual applications obsolete Include more network applications Support natural language interfaces such
talking to the machine Include artificial intelligence and agents Be based on virtual reality
Future interfaces will probably:
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