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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.
    Upgrades
  • 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”