Operating Systems

Operating Systems

1. Providing an interface

   • Graphical user interface
     • Graphical representations of the computer’s functions are shown to the user
       • controlled by mouse and keyboard
     • Programs often run in windows and several can be shown at the same time
   • command line interface
     • text based interface
     • The user types commands, and the result is shown as text.
     • These are harder to use, but are very lightweight and robust
       • this means they are hard to crash
   • Managing files
     • Copy files
     • Move files
     • Delete files
     • Sort files
     • Search for files
   • System Settings
     • Enabling or disabling specific hardware
     • Changing the volume
     • Adjusting screen resolution
     • Configuring secondary storage
   • Multi Tasking
     • allows multiple processes appear to run simultaneously.
     • the OS simulates it by alternating which processes get CPU time.
     • run in separate windows, and be displayed side by side.
   • Error messaging and support
     • the programmer may not know how the program is being used
     • The error is passed to the operating system, which then displays it in the most suitable way.
     • This produces consistent error handling regardless of what application is being used.
   • Customisation
     • The ability to customise the interface is a feature of most operating systems.
     • Some provide options to change the colour scheme and desktop background
     • Others allow a completely different desktop environment to be installed.
   • Task managing
     • Operating systems manage processes and allow multitasking
     • The also provide the user with the option to quit programs, or kill unresponsive processes
     • Some also allow the user to prioritise certain processes, allowing certain apps to use the full processor speed.
   • GUI vs CLI
     • GUI
       • ADVANTAGES
         • Easy to learn
         • Lots of information shown at once
       • DISADVANTAGES
         • Uses a lot of system resources
         • Complexity means there is more to go wrong
     • CLI
       • ADVANTAGES
         • Few system resources required
         • Easy to automate (commands can be stored in file)
       • DISADVANTAGES
         • Hard to learn
         • Difficult to compare outputs of different programs