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Software BasicsSoftware Basics
The Ghost in the Machine
4
2001 Prentice Hall 4.2
Chapter Outline
• 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
“All experience shows technological changes profoundly transform political and social relationships.”
John von Neumann
2001 Prentice Hall 4.3
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 4.4
Food for Thought
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
Suzanne’s French Toast Fantastique:
2001 Prentice Hall 4.5
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 4.6
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 4.7
Programming Languages
Bridge the gap
Human language
Numeric code
COBOL, BASIC, and C++
2001 Prentice Hall 4.8
Software Applications:Tools for Users
Software applications include:
– Consumer software
– Integrated software
– Vertical-market and custom software
2001 Prentice Hall 4.9
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 4.10
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 4.11
Upgrades
• Newer releases often have additional features and fewer bugs
• Upgrades allow you to pay a fee to get the latest software version
2001 Prentice Hall 4.12
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
2001 Prentice Hall 4.13
Warranty
• Software manufacturers limit their liability for software problems byselling their software “as is”
• Error-free software does not exist
Buyer Beware!
2001 Prentice Hall 4.14
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 4.15
Integrated Applications and Suites:
Software Bundles
• Multipurpose software includes most of these modules:
– Word processing
– Database
– Spreadsheet
– Graphics
– Telecommunications
2001 Prentice Hall 4.16
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 4.17
Vertical-Market andCustom Software
• Job-specific software:
- Medical billings
- Library cataloging
- Restaurant management
- Single-client software needs
2001 Prentice Hall 4.18
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 4.19
Utility Programs
– repairing damaged files
– making it easy for users to copy files from one storage device to another
– translating files so differentsoftware can read them
– guarding against viruses
Utility software controls tasks such as:
2001 Prentice Hall 4.20
Where the Operating System Lives
• 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
• Some computers store their operating system in ROM
2001 Prentice Hall 4.21
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 4.22
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 4.23
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 4.24
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, theMacintosh™ computerwas designed with thisinterface in mind
2001 Prentice Hall 4.25
Graphical User Interfaces: Windows
• Windows 95and 98 are similar in many ways to the Mac OS
• Several versions of Windows exist for business and home users
2001 Prentice Hall 4.26
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 4.27
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 4.28
• UNIX remains a dominant Internet operating system for Internet servers.
Multiple User Operating Systems: UNIX and Linux
• These systems allow a timesharing computer to communicate with several other computers or terminals at once.
2001 Prentice Hall 4.29
Hardware & Software Platforms
• Windows 9x(ME)
• Windows 2000
• Windows CE
• Palm OS
• IBM’s OS/2
• Mac OS/9
• Mac OS/X
• UNIX & Linux
• BeOS
2001 Prentice Hall 4.30
Rules of ThumbConsumer Concepts
Before you buy:
– Join a user group ortalk with other computerand software owners
– Allow for “extras”
– Determine what you can afford
2001 Prentice Hall 4.31
Rules of Thumb: Consumer Concepts
• What kind of tasks you will be doing
• If your computer can be customized to fit your needs (such as video editing)
• How much computer power you need
Consider:
• If the processor canhandle your demands
• If you will be able to upgrade
2001 Prentice Hall 4.32
Rules of Thumb: Consumer Concepts
• If you need a high-speed modem or network connection
• Whether portability or permanent connection of peripherals is important
• Which kind of user interface will help you do your work easier
Consider:
• If you should have the same machine as those you work with
• If you are buying from a reputable company
• What kind of support is available
2001 Prentice Hall 4.33
Tomorrow’s User Interfaces
– Make individual applications obsolete
– Support natural languages(talk to the machine and it talks back)
– Include artificial intelligenceand agents that fit our needs
– Be based on virtual reality(data in three-dimensional physical space)
Future interfaces will probably: