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    SoftwareOS.ppt SoftwareOS.ppt Presentation Transcript

    • Software Basics System and Application Software CIS 110 Intro to Computing
    • Software Topics
      • Processing with Programs
      • Software Applications: Tools for Users
      • System Software: The Hardware-Software Connection
      • The User Interface: The Human-Machine Connection
    • Processing with Programs
      • Software programs are:
      • Stored in memory
      • Instructions that tell the computer what to do (encoded in binary).
      • Designed to solve problems
    • A Fast, Stupid Machine
      • Computers:
      • Perform arithmetic and comparisons capabilities
      • Follow precise instructions to perform an operation
      • Execute instructions quickly and accurately -- but have absolutely NO “common sense”
    • A Fast, Stupid Machine
      • Programmers begin with an algorithm
      • An algorithm is:
        • A set of step-by-step instructions for accomplishing a task (solving a problem)
      • Usually begins written in a natural language, e.g., English – computer cannot understand
      • Algorithms are translated into the vocabulary of a programming language
    • The Language of Computers
      • Machine Language -- numeric codes to represent instructions as well as data
      • High-level language falls between machine language and natural human language
      • “ Compiler” translates high-level language written by programmer into Machine language.
    • Application Software: Tools for Users
      • Software applications include:
      • Consumer Applications
      • Integrated Software
      • Vertical-market
      • Custom Software
    • Consumer Applications
      • Consumer software differs from other types (music CDs, videos, etc.) based on:
        • Documentation
        • Upgrade options
        • Compatibility
        • Warranty
        • Extent of ownership/license
    • 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
      • Upgrades allow you to pay a smaller fee to get the latest software version
      • Newer releases usually have additional features and fewer bugs (hopefully).
      • Companies do this to compete, plus they like a reliable revenue stream year after year.
    • 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 – must match the machine language of the CPU chip.
    • 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.
    • Licensing
      • Other Kinds of Licensing :
        • Public Domain free, author gives up rights
        • Freeware free to use but author retains rights
        • Shareware freely copied but only for trial , must pay if you keep. also crippleware, nagware
      • “ Open Source” Movement ex. Linux
        • Source code as well as finished programs
        • Free to use, modify, but must pass on w/ GPL. Companies may only profit from sales of media & installation, training and support services
    • Distribution
      • Software is also sold through:
        • “brick and mortar” retail stores
        • mail-order catalogs and web sites
        • direct download
      • Software is often distributed by direct sales for corporations and other large customers.
    • Integrated Software Apps: Office “Suites”
      • Business software includes most of these modules:
        • Word processing
        • Database
        • Spreadsheet
        • Graphics or Desktop Publishing
      • Modules also available individually.
    • 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.
      • Seamless integration is the goal.
    • Vertical-Market and Custom Software
      • Job/Industry-specific software:
        • Hospital administration
        • Restaurants
        • Manufacturing
      • Large companies often require customized software for their special needs.
    • System Software: The Hardware-Software Connection
      • System software is a class of software that includes:
        • The operating system
        • Device Drivers
        • Utility programs
      • Purpose is supporting the operation of the computer itself.
    • Utility Programs
      • Examples:
      • Anti-Virus
      • Firewall
      • Backup
      • Disk Utilities
      These address other machine-oriented issues that are not handled by Operating System
    • What the Operating System Does
      • At the simplest level, the Operating System
        • Manages physical resources (hardware).
        • Provides the essentials of a user interface.
        • Supplies services to other programs.
    • What the Operating System Does -- Details
      • 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
    • Where the Operating System Lives
      • Most computers store the OS on disk.
      • It must be loaded into main memory (RAM) to run. The BIOS does this when the machine “boots”.
      • Some special purpose computers (embedded systems) run it directly from ROM.
    • Device Drivers
      • Special programs that help the OS understand & control special hardware devices.
      • Written by H/W and OS manufacturers
      • Ex: drivers for
        • Video card -- Network Adapter
        • Sound card -- Printer
    • The User Interface: The Human-Machine Connection
      • The user interface is what the user sees on the screen and how he interacts with it.
      • Two major user interface types:
        • Character-based “command line”
        • Graphical User Interface “GUI” with graphical windows, icons, mouse
    • A Character-Based Interface: MS-DOS or the Windows “Command Prompt”
      • The user interacts with the OS using commands composed of
        • letters
        • numbers
        • symbols
    • DOS Command Line: dir Command
    • DOS Text Mode “GUI” Some later DOS programs worked somewhat like a GUI.
    • Graphical User Interfaces: Apple Macintosh
      • First commercially successful operating system in which the user interacts with the computer by using a pointing device (e.g. a mouse) and a graphical display full time.
      • Mid 1980’s.
    • Original Apple Macintosh
    • Current Mac OS X
    • Graphical User Interfaces: Microsoft Windows
      • Windows 95/98/Me and XP are similar in many ways to the Mac OS.
      • Several versions of Windows exist for business and home users.
      • Windows has largest share of the desktop market.
    • Windows 1.0 More or less a bad joke.
    • Windows 3.0 First version to be a clear success in early 1990s.
    • Why GUIs Won
      • W indows, I cons, M enus, and P ointing devices
      • They’re intuitive
      • They’re consistent
      • They’re forgiving
      • They’re protective
      • They’re flexible
    • 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
      • 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.
      • Linux is a free “open source” based on the MINIX OS (UNIX Clone).
      • Both command-line and GUIs available.
      Multi-User Operating Systems: UNIX and Linux
    • A Windows-like Linux GUI -- KDE
    • O/S Wars
      • MS-DOS versus DR-DOS
      • IBM OS/2 versus MS Windows
      • Windows versus Macintosh OS Pirates of Silicon Valley
      • MS versus Novell Netware
      • Linux versus Windows – on the server
      • Linux vs Windows – on the desktop?
    • File System Management
      • DOS stands for Disk Operating System
      • With transition from tape to disks, a method for organizing large numbers of data files was needed.
      • Files are grouped into a hierarchy of directories (almost all OSes do this).
      • GUIs represent these visually as nested folders.
    • Directories / Folders In DOS/Windows each drive has own root. Files are located by path such as c:Documents and SettingsUser1My Documents eport.doc
    • Software Issues
      • Piracy
      • Look-and-Feel lawsuits
      • Software patents
      • DMCA
    • Buzzwords
      • “ Killer App” - killer application
      • New program or software category that “everyone” (business or home users) wants/needs.
      • Marketing people want to know the next bandwagon to jump on, to get ahead of competition.
      • “ Killer apps” can drive hardware sales.
    • BSOD – “Blue Screen of Death”