 2002 Prentice Hall Chapter 4 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

 2002 Prentice Hall 4 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:

 2002 Prentice Hall 5 A Fast, Stupid Machine Computers: Perform arithmetic and comparisons capabilities Follow precise instructions to perform an operation Execute instructions quickly and accurately

 2002 Prentice Hall 6 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

 2002 Prentice Hall 7 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

 2002 Prentice Hall 8 Software Applications: Tools for Users Software applications include: Consumer Applications Integrated Software Vertical-market Custom Software

 2002 Prentice Hall 9 Consumer Applications Consumer software differs from other types (music CDs, videos, etc.) based on:  Documentation  Upgrade options  Compatibility  Warranty  Extent of ownership/license

 2002 Prentice Hall 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

 2002 Prentice Hall 11 Upgrades allow you to pay a fee to get the latest software version Newer releases often have additional features and fewer bugs Upgrades

 2002 Prentice Hall 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

 2002 Prentice Hall 13 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

 2002 Prentice Hall 14 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.

 2002 Prentice Hall 15 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.

 2002 Prentice Hall 16 Integrated Applications and Suites: Software Bundles Multipurpose software includes most of these modules:  Word processing  Database  Spreadsheet  Graphics  Telecommunications

 2002 Prentice Hall 17 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

 2002 Prentice Hall 18 Vertical-Market and Custom Software Job-specific software:  Medical billings  Library cataloging  Restaurant management  Single-client software needs

 2002 Prentice Hall 19 System Software: The Hardware- Software Connection System software is a class of software that includes:  The operating system  Utility programs

 2002 Prentice Hall 20 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

 2002 Prentice Hall 21 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

 2002 Prentice Hall 22 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

 2002 Prentice Hall 23 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)

 2002 Prentice Hall 24 A Character-Based Interface: MS-DOS This is a disk operating system in which the user interacts using characters  letters  numbers  symbols

 2002 Prentice Hall 25 A Character-Based 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)

 2002 Prentice Hall 26 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

 2002 Prentice Hall 27 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

 2002 Prentice Hall 28 Why WIMP Won Windows, Icons, Menus, and Pointing devices They’re intuitive They’re consistent They’re forgiving They’re protective They’re flexible

 2002 Prentice Hall 29 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

 2002 Prentice Hall 30 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

 2002 Prentice Hall 31 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 BeOS

 2002 Prentice Hall 32 Tomorrow’s User Interfaces  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 Future interfaces will probably:

 2002 Prentice Hall 33 Rules of Thumb Consumer Concepts  Determine what you can afford  Allow for “extras”  Join a user group or talk with other computer and software owners Before you buy:

 2002 Prentice Hall 34 Rules of Thumb: Consumer Concepts Consider:  If the processor can handle your demands  If you will be able to upgrade  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

 2002 Prentice Hall 35 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  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 Consider:

 2002 Prentice Hall 36