Computer Confluence 6/e

1. Computer Confluence 6/e © 2003 Prentice-Hall, Inc.

2. Computer Confluence 6/e Chapter 4 Software Basics: The Ghost in the Machine © 2003 Prentice-Hall, Inc.

3. Computer Confluence 6/eChapter 4Objectives Describe three fundamental categories of software and their relationship Explain the relationship of algorithms to software Discuss the factors that make a computer application a useful tool Describe the role of the operating system in a modern computer system Outline the evolution of user interfaces from early machine-language programming to futuristic virtual-reality interfaces © 2003 Prentice-Hall, Inc.

4. Computer Confluence 6/e Chapter 4 Linus Torvalds and the Software Nobody Owns Linus Torvalds Best known as the Linux creator The Linux operating system is the best-known example of open source software Today Linux powers Web servers, film and animation workstations, scientific supercomputers, and a handful of handhelds © 2003 Prentice-Hall, Inc.

5. Computer Confluence 6/e Chapter 4 Linus Torvalds and the Software Nobody Owns The three major categories of software: Compilers and other translator programs: enable programmers to create other software Software applications: serve as productivity tools to help computer users solve problems System software: coordinates hardware operations and does behind-the-scenes work the computer user seldom sees OS vs. Application software © 2003 Prentice-Hall, Inc.

6. Computer Confluence 6/e Chapter 4 Processing with Programs Food for Thought The hardware in a computer system is equipped to produce whatever output a user requests © 2003 Prentice-Hall, Inc.

7. Computer Confluence 6/e Chapter 4 Processing with Programs A Fast, Stupid Machine Programmers begin with an algorithm: a set of step-by-step instructions Written in a natural language, e.g., English Ambiguous, error-prone generalities Translated into the vocabulary of a programming language © 2003 Prentice-Hall, Inc.

8. Computer Confluence 6/e Chapter 4 Processing with Programs The programmer, like the poet, works only slightly removed from pure thought-stuff. He builds castles in the air, creating by exertion of the imagination. Yet the program construct, unlike the poet’s words, is real in the sense that it moves and works, producing visible outputs separate from the construct itself. —Frederick P. Brooks, Jr., in The Mythical Man Month The Language of Computers Machine Language: numeric codes that represent data High-level language: falls between machine language and natural human language Compilers translate high-level language into machine language Natural Languages: resemble languages spoken by humans © 2003 Prentice-Hall, Inc.

9. Computer Confluence 6/e Chapter 4 Software Applications: Tools for Users ConsumerApplications Many software companies have replaced their printed documentation with: Tutorials Reference materials Help files On-line help Upgrading: users can upgrade a program to the new version by paying an upgrade fee to the software manufacturer Newer releases often have additional features and fewer bugs © 2003 Prentice-Hall, Inc.

10. Computer Confluence 6/e Chapter 4 Software Applications: Tools for Users 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 Disclaimers Software manufacturers limit their liability for software problems by selling software “as is” © 2003 Prentice-Hall, Inc.

11. Computer Confluence 6/e Chapter 4 Software Applications: Tools for Users Licensing: commercial software is copyrighted so it can’t be legally duplicated for distribution to others Software license Volume licenses Distribution: software is distributed via Direct sale Retail stores Mail-order catalogs Web sites Not all software is copyrighted Public domain software Shareware © 2003 Prentice-Hall, Inc.

12. Computer Confluence 6/e Chapter 4 Software Applications: Tools for Users Why We Use Applications: most successful software products share two important characteristics: They are built around visual metaphors of real-world tools They extend human capabilities in some way © 2003 Prentice-Hall, Inc.

13. Computer Confluence 6/e Chapter 4Integrated Applications and Suites: Software Bundles Integrated software packages: Include several applications designed to work well together Enable automatic transfer of data between modules Cost less than buying the applications individually Use the same type of commands in each module © 2003 Prentice-Hall, Inc.

14. Computer Confluence 6/e Chapter 4Integrated Applications and Suites: Software Bundles Popular integrated packages, like AppleWorks and Microsoft Works, generally include: Word processing Database Spreadsheet Graphics Telecommunication Personal information management (PIM) modules © 2003 Prentice-Hall, Inc.

15. Computer Confluence 6/e Chapter 4Integrated Applications and Suites: Software Bundles Application suites: bundles containing several full application programs that are also sold as separate programs The core applications of the Microsoft Office System (the most popular application suite) include: Word (a word processing program) Excel (a spreadsheet program) PowerPoint (a presentation graphics program) Access (a database program) Outlook (an email/personal-information management program) © 2003 Prentice-Hall, Inc.

16. Computer Confluence 6/e Chapter 4Integrated Applications and Suites: Software Bundles Vertical-Market and Custom Software Tends to cost far more thanmass-market applications Job-specific software: Medical billings Library cataloging Legal reference software Restaurant management Single-client software needs © 2003 Prentice-Hall, Inc.

17. Originally, operating systems were envisioned as a way to handle one of the most complex input/output operations: communicating with a variety of disk drives. But, the operating system quickly evolved into an all-encompassing bridge between your PC and the software you run on it. —Ron White, in How Computers Work Computer Confluence 6/e Chapter 4 System Software: The Hardware-Software Connection What the Operating System Does System software A class of software that includes the operating system and utility programs, handles these details, and hundreds of other tasks behind the scenes © 2003 Prentice-Hall, Inc.

18. Computer Confluence 6/e Chapter 4 System Software: The Hardware-Software Connection Operating system functions: Communicating with peripherals Coordinating concurrent processing of jobs Memory management Resource monitoring, accounting, and security Program and data management Coordinating network communications © 2003 Prentice-Hall, Inc.

19. Computer Confluence 6/e Chapter 4 System Software: The Hardware-Software Connection Utility Programs and Device Drivers Utility programs Serve as tools for doing system maintenance and repairs that aren’t automatically handled by the operating system Make it easier for users to: Copy files between storage devices Repair damaged data files Translate files so that different programs can read them Guard against viruses and other potentially harmful programs (as described in the chapter on computer security and risks) Compress files so they take up less disk space Perform other important, if unexciting, tasks © 2003 Prentice-Hall, Inc.

20. Computer Confluence 6/e Chapter 4 System Software: The Hardware-Software Connection Symantec Norton Utilities is a popular utility package that includes software tools for recovering damaged files, repairing damaged disks, and improving disk performance © 2003 Prentice-Hall, Inc.

21. Computer Confluence 6/e Chapter 4 System Software: The Hardware-Software Connection Device drivers Small programs that enable I/O devices—keyboard, mouse, printer, and others—to communicate with the computer Included with the operating system or bundled with peripherals © 2003 Prentice-Hall, Inc.

22. Computer Confluence 6/e Chapter 4 System Software: The Hardware-Software Connection • Where the Operating System Lives • Some computers store their operating system in ROM • Others include only part of it in ROM • The remainder of the operating system is loaded into memory in a process called booting, which occurs when you turn on the computer © 2003 Prentice-Hall, Inc.

23. Computer Confluence 6/e Chapter 4 System Software: The Hardware-Software Connection • Most of the time it works behind the scenes • Interacting with the operating system, like interacting with an application, can be intuitive or challenging and it depends on something called the user interface © 2003 Prentice-Hall, Inc.

24. Computer Confluence 6/e Chapter 4 The User Interface: The Human–Machine Connection User interface The look and feel of the computing experience from a human point of view Desktop Operating Systems MS-DOS is a disk operating system in which the user interacts using characters Letters Numbers Symbols © 2003 Prentice-Hall, Inc.

25. Computer Confluence 6/e Chapter 4 The User Interface: The Human–Machine Connection Features include: Command-line interface (commands are typed) Menu-driven interface (commands are chosen from on-screen lists) © 2003 Prentice-Hall, Inc.

26. Computer Confluence 6/e Chapter 4 The User Interface: The Human–Machine Connection Graphical User Interfaces Mac OS This is a disk operating system in which the user interacts with the computer by using a pointing device (e.g., a mouse) © 2003 Prentice-Hall, Inc.

27. Computer Confluence 6/e Chapter 4 The User Interface: The Human–Machine Connection Microsoft Windows Originally, Microsoft Windows (commonly called Windows) was a type of program, known as a shell, which put a graphical face on MS-DOS With the introduction of Windows 95 in 1995, Microsoft began transitioning Windows from an operating system shell into a full operating system that seldom showed its MS-DOS roots The latest Windows versions have no ties at all to the DOS past The Windows XP GUI © 2003 Prentice-Hall, Inc.

28. Computer Confluence 6/e Chapter 4 The User Interface: The Human–Machine Connection File Management: Where’s My Stuff? Files can be scattered all over the system, which often makes data management difficult One solution to this problem is to organize data files logically Both Windows and the Mac support the notion of common system folders with self-explanatory names: My Documents (Documents) My Pictures (Pictures) My Music (Music) © 2003 Prentice-Hall, Inc.

29. Computer Confluence 6/e Chapter 4 The User Interface: The Human–Machine Connection 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 Allow a timesharing computer to communicate with several other computers or terminals at once © 2003 Prentice-Hall, Inc.

30. Computer Confluence 6/e Chapter 4 The User Interface: The Human–Machine Connection Linux is free for anyone to use or improve UNIX remains the dominant operating system for Internet servers Some form of UNIX is available for personal computers, workstations, servers, mainframes, and supercomputers © 2003 Prentice-Hall, Inc.

31. Computer Confluence 6/e Chapter 4 The User Interface: The Human–Machine Connection Windows XP Windows Sever 2003 Windows ME Windows 2000Microsoft Windows CE .NET Palm OS Mac OS X (10). Mac OS 9 Linux, Sun Solaris, and other UNIX variations Hardware and Software Platforms © 2003 Prentice-Hall, Inc.

32. Computer Confluence 6/e Chapter 4 The User Interface: The Human–Machine Connection Cross-platform applications, such as Microsoft Office and Adobe Photoshop Programs that are available in similar versions for multiple platforms Mac users can buy software emulation programs that: Create a simulated Windows machine in the Mac Translate all Windows-related instructions Mac equivalents Future applications may be more tied to networks than to desktop computer platforms Microsoft .NET strategy Java, a platform-neutral computer language developed by Sun Microsystems for use on multiplatform networks © 2003 Prentice-Hall, Inc.

33. Computer Confluence 6/e Chapter 4 Rules of Thumb: Green Computing Tips to choose and use computer hardware and software in an environmentally responsible way: Buy green equipment Use a notebook Take advantage of energy-saving features Turn it off when you’re away Save energy, not screens Print only once Recycle your waste products Pass it on Send bits, not atoms © 2003 Prentice-Hall, Inc.

34. Computer Confluence 6/eChapter 4 The User Interface: The Human–Machine Connection Tomorrow’s User Interfaces: future user interfaces will be built around emerging development technologies such as: The end of applications Natural-language interfaces Agents Virtual realities © 2003 Prentice-Hall, Inc.

35. Our goal was bug-free. The new goal is resiliency. —Bob Frankston, in Beyond Calculation Computer Confluence 6/eChapter 4 Inventing the Future Tomorrow’s Evolving Applications and Interfaces WIMP (windows, icons, menus, and pointing devices) interface Easier to learn and use than earlier character-based interfaces SILK interface incorporates many important emerging user interface software technologies: Speech and language Image Knowledge © 2003 Prentice-Hall, Inc.

36. Computer Confluence 6/eChapter 4Lesson Summary This chapter provides some general answers to the “What is software” question, along with details about each of the three major categories of software: Compilers and other translator programs, which enable programmers to create other software Software applications, which serve as productivity tools to help computer users solve problems System software, which coordinates hardware operations and does behind-the-scenes work the computer user seldom sees © 2003 Prentice-Hall, Inc.

37. Computer Confluence 6/e Chapter 4Lesson Summary (continued) Offers tips to choose and use the best environmental computer hardware and software Introduces emerging technologies that offer promise for future improved Applications and Interfaces © 2003 Prentice-Hall, Inc.