Operating System

Operating System

1. Providing an Interface

   • Graphical User Interface (GUI)
     • A GUI is used by most PC and phone operating systems
     • Programs are often run in windows and several can be shown at the same time
     • Graphical representations of the PC functions are shown to the user
     • Functions are controlled by touchscreen or mouse and keyboard
   • Command Line Interface (CLI)
     • A text based interface
     • Uses commands and the result is shown as text
     • Nearly every OS provides a CLI
     • These are harder to use but are lightweight and robust
     • Use few system resources
     • Unlikely to crash or break
   • File Management
     • Files need to be manipulated
     • OS provide an interface which allows the user to
     • Copy files
     • Move files
     • Delete files
     • Sort files
     • Search for files
   • System Settings
     • Operating sytsems enable the user to alter system settings
     • Changing the volume
     • Adjusting screen resolution
     • Configuring secondary storage
     • Enabling or disabling specific hardware
   • Multi Tasking
     • Multitasking is allowing multiple processes to appear to run simultaneously
     • CPU's don't generally support this, so the OS simulates it by alternating which processes get CPU time
     • A GUI will generally allow different processes to run in separate windows and be displayed side by side
   • Error Messages and Support
     • When a program goes wrong the user needs to be informed
     • However the programmer may not know how the programmer is being used (GUI, CLI or remotley embedded)
     • The error is passed to the OS, which displays it in the most suitable way
     • This allows for consistent error handling regardless of the application being used.
   • Customisation Options
     • Most operating systems provide the ability to customise the interface
     • Some provide options to change colour scheme and desktop background
     • Some operating systems allow a completely different desktop and environment to be installed.
   • Task Management
     • Operating systems manage processes and multitasking
     • They provide the user with an option to quit the program or kill unresponsive processes
     • Some allow the user to prioritise certain processes or allow certain apps to use the full processor speed.
   • Comparing GUI and CLI
     • GUI
       • Copying a file
         • Open a window and navigate to the file
           • Drag the file from the current location to the new one or use context menus to copy and paste
       • Viewing contents of a folder
         • Open file explorer and navigate to folder
           • Folder contents shown as icons
       • 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
       • Copying a file
         • Type the command to copy the file
       • Viewing contents of a folder
         • Type command
           • Folder contents shown as text
       • 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