1Slide 1Tomorrow’s Technologyand You 8th Edition© 2008 Prentice-Hall, Inc.Slide 2Tomorrow’s Technologyand You 8/eChapter 4Software Basics: The Ghostin the Machine© 2008 Prentice-Hall, Inc.Slide 3Tomorrow’s Technology and You 8/eChapter 4Objectives Describe three fundamental categories of software and theirrelationship. Explain the relationship of algorithms to software. Discuss the factors that make a computer application a usefultool. Describe the role of the operating system in a modern computersystem.© 2008 Prentice-Hall, Inc.2Slide 4Tomorrow’s Technology and You 8/eChapter 4Objectives Describe how file systems are organized. Outline the evolution of user interfaces from early machine-language programming to futuristic virtual-reality interfaces. Explain why unauthorized copying of software is againstthe law.© 2008 Prentice-Hall, Inc.Slide 5Tomorrow’s Technology and You 8/eChapter 4 Linus Torvalds and the SoftwareNobody Owns Linus Torvalds Best known as the Linux creator The Linux operating system is the best-known example of open sourcesoftware. Today Linux powers Web servers, filmand animation workstations, scientificsupercomputers, and a handful ofhandhelds.© 2008 Prentice-Hall, Inc.Slide 6Tomorrow’s Technology and You 8/eChapter 4 Linus Torvalds and the SoftwareNobody Owns The three major categories of software: Compilers and other translator programs:enable programmers to create othersoftware Software applications: serve asproductivity tools to help computer userssolve problems System software: coordinates hardwareoperations and does behind-the-sceneswork the computer user seldom sees OS vs. Application software© 2008 Prentice-Hall, Inc.3Slide 7Tomorrow's Technology and You 8/eChapter 4 Processing with Programs© 2008 Prentice-Hall, Inc. Food for Thought The hardware in a computer system is equipped to producewhatever output a user requests.Slide 8Tomorrow’s Technology and You 8/eChapter 4 Processing with Programs A Fast, Stupid Machine Programmers begin with an algorithm: a set of step-by-step instructionswritten in a natural language, e.g., English. The steps are often ambiguous, error-prone generalities. The steps are translated into the vocabulary of a programminglanguage.© 2008 Prentice-Hall, Inc.Slide 9Tomorrow’s Technology and You 8/eChapter 4 Processing with Programs The Language of Computers Machine Language: numeric codes thatrepresent data High-level language: falls betweenmachine language and natural humanlanguageCompilers translate high-level languageinto machine language. Natural Languages: resemble languagesspoken by humans© 2008 Prentice-Hall, Inc.The programmer, like the poet, worksonly slightly removed from pure thought-stuff. He builds castles in the air,creating by exertion of the imagination.Yet the program construct, unlike thepoet’s words, is real in the sense that itmoves and works, producing visibleoutputs separate from the construct itself.—Frederick P. Brooks, Jr., inThe Mythical Man Month4Slide 10Tomorrow’s Technology and You 8/eChapter 4 Software Applications: Tools for Users Consumer Applications Many software companies have replaced their printeddocumentation with: Tutorials Reference materials Help files On-line help Upgrading: Users can upgrade a program to the new version bypaying an upgrade fee to the software manufacturer. Newer releases often have additional features and fewer bugs.© 2008 Prentice-Hall, Inc.Slide 11Tomorrow’s Technology and You 8/eChapter 4 Software Applications: Tools for Users Compatibility It allows software to functionproperly with the hardware,operating system, and peripherals. Programs written for one type ofcomputer system may not workon another. Disclaimers Software manufacturers limittheir liability for softwareproblems by selling software “asis.”© 2008 Prentice-Hall, Inc.Slide 12Tomorrow’s Technology and You 8/eChapter 4 Software Applications: Tools for Users Licensing: Commercial software is copyrighted so it can’tbe 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© 2008 Prentice-Hall, Inc.5Slide 13Tomorrow’s Technology and You 8/eChapter 4 Web Applications Web applications fall into several categories: Some simple Web applications perform simple data-processing tasksthat could also be performed by traditional programs running onstand-alone PCs. Most Web applications take advantage of the Web’s connectivity. Many Web applications leverage the Web’s strength as a huge repositoryof information. Some Web applications support online business transactions. News-oriented Web applications provide up-to-the-minute reports on amyriad of subjects. Other Web applications support a more traditional form of informationbroadcasting.© 2008 Prentice-Hall, Inc.Slide 14Tomorrow’s Technology and You 8/eChapter 4 Integrated 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© 2008 Prentice-Hall, Inc.Slide 15Tomorrow’s Technology and You 8/eChapter 4 System Software:The Hardware-Software ConnectionWhat 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.© 2008 Prentice-Hall, Inc.Originally, operating systems were envisioned as away to handle one of the most complex input/outputoperations: communicating with a variety of diskdrives. But, the operating system quickly evolvedinto an all-encompassing bridge between your PCand the software you run on it.—Ron White, in How Computers Work6Slide 16Tomorrow’s Technology and You 8/eChapter 4 System Software:The Hardware-Software Connection Operating system functions: Supports multitasking Manages virtual memory Maintains file system Responsible for authentication and authorization© 2008 Prentice-Hall, Inc.Slide 17Tomorrow’s
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