Computer Software

• Interfaces
  • We interact with the computer (or anything really) through a user interface.
  • There are many different styles, and looks but mostly they break into two classes:
  • CLI
    • Command Line Interface
    • User mostly interacts by typing commands, and moving a cursor around the screen.
    • The user usually needs to memorize many different commands
    • 
    • Large learning curve, highly usable afterwords
    • Less impact when the system is changed.
    • 
  • Graphical User Interface
    • Commands are represented as icons or in drop down menus
    • 
    • User must locate, and click on a command to execute it.
    • Usually easier to start using
    • Slower for experienced users to accomplish tasks.
  • Which is easier?
  • Mixtures
    • Some applications make allowances for both
    • 
    • In this case, Alt-S will save the page.
    • This allows the connivance of a GUI with the speed of a CLI.
  • Common User Interface
    • Make different programs have a common look
    • Functions are located in similar locations
    • General behavior is the same
    • This makes it easier to learn how to use a new but related application.
    • You will like this, Word, Powerpoint and Excel "look" alike.
• Software development
  • An algorithm is a step by step set of instructions that solve a problem in a finite amount of time.
    • For example :

      To Fix Breakfast
         1. Get a bowl
         2. Get a spoon
         3. Get Milk
         4. Get Super Crunchy Chocolate Bombs (SCCB)
         5. Pour SCCB into bowl
         6. Pour Milk onto bowl
         7. Enjoy
         8. Full?
            A.  No - goto 5
         9. Put everything away.
      	 

  • Source Code
    • Written in a programming language
    • These are more formal than the language you write the algorithm in
    • Tells us exactly how to solve the problem
  • Executable
    • Source code that is compiled into something that can be run on the computer.
    • Machine Language.
    • Not readable by humans.
    • Not very easy to modify.
  • Bug
    • A problem in a program
    • Go to www.google.com and search for first bug
    • A major part of the software development cycle is to find and remove bugs
    • This sometimes introduces more bugs.
  • Patch
    • Regularly during the life of software, patches are released
    • These fix the bugs in executable
    • Mostly Free
  • Versions, releases and other things
    • Adding features
    • Fixing bugs
    • Mostly for charge, but sometimes just an upgrade fee.
    • N.n (3.1, 4.12)
• System Software
  • Purpose
    • To act as an interface between the user and the hardware.
    • To facilitate the sharing of resources.
    • To make the machine easier to use.
  • Some Terms
    • Multi-user
    • Multi-tasking
  • DOS
    • Disk Operating System
    • CLI
    • Fairly Primitive
  • Windows
    • GUI for DOS
    • Many different versions here
    • Personal Versions:
    • 3.1 -> 95 -> 98 -> ME
    • Professional Versions:
    • 3.1 -> NT -> 2000 -> XP
  • MacOS
  • Unix
    • Programming environment
    • Server, (web pages, dialup, ...)
    • Flexible, but much to learn to use it.
  • Others
    • Many others exist.
• Utility Software
  • Nice things to have
  • Not essential for the machine to run
  • Notepad, paint, ...
  • Usually small and single purpose.
  • Free, or low cost, (more later)
• Application Software
  • Much broader in scope
  • Usually larger
• Ownership
  • Commercial
  • Open Source
  • Freeware
  • Copyright
  • Piracy
    • Is it right to take bread if you are starving
    • What about just as a joke
    • What about as a regular practice
    • Why do people bake bread
    • Is it ok to steel from Schwable's
• Some Applications
  • Word Processing
  • Presentation
  • Spreadsheet
  • Browsers