Operating Systems

Operating Systems

1. Managing resources

   • Managing Peripherals
   • Managing Processes
   • Managing memory

2. Providing an interface

   • Graphical User Interface (GUI)
     • This is used by most PC and phone operating systems. Graphical representations of the computer's functions are shown to the user and controlled by touchscreen or a mouse and keyboard. Programs often run in windows and several can be shown at the same time
     • Easy to learn
     • Lots of information shown at once
     • Uses a lot of system resources
     • Complexity means more could go wrong
   • Command line Interface (CLI)
     • This is a text-based interface where the user types commands, and results are shown as text. Nearly every operating system provides a CLI; they are harder to use, but are very lightweight and robust - they use few system resources and are very unlikely to crash or break
     • Few system resources required
     • Easy to automate; commands can be stored in file
     • Hard to learn
     • Difficult to compare outputs of different programs
   • File management
     • OSs allow the user to:
       • Copy files
       • Move files
       • Delete files
       • Sort files
       • Search for files
   • System settings
     • System settings enable the user to easily alter system settings
     • Examples
       • Enabling or disabling specific hardware
       • Changing the volume
       • Adjusting the screen resolution
       • configuring secondary storage
   • Error messages and support
     • When something goes wrong in a program, the user needs to be informed. However, the programmer may not know how the program is being used (GUI, CLI or remotely on an embedded system). The error is passed to the OS, 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, while others allow a completely different desktop environment to be installed
   • Task management
     • Operating systems manage processes and allow multitasking.  They 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

3. Examples

   • Desktop examples
     • Windows
     • Mac OS
     • Linux
     • Unix
   • Portable device examples
     • Android
     • iOS
     • Windows 8/10
     • Blackberry OS

4. Controls hardware

5. Allows multitasking

   • Where a processor appears to carry out two tasks simultaneously, wheres in reality the processor is running the commands from each task separately, but fills in the time spent waiting for the other components to finish.

6. Contains Utility sofware

   • Compression
     • The storing of data by using less disk space.  Lossless compression preserves the orginal file exactly as it was before, whereas lossy compression loses some information of the original file but is much more effective in terms of compression.
   • Disk formatting
     • Disks, USB sticks and memory cards etc all need formatting before they can be used. A disk formatter configures the disk so that it is read to have files written to it 
   • Defragmenting
     • Over time a file will become fragmented and different parts of the file will become scattered around different parts of the disk, making access slower than it could be. A disk defragmentor puts these fragments back together to speed up access
   • Firewall and antivirus
   • Drivers
     • Drivers are special types of software that lets the operating system communicate properly with the hardware.  A 'device driver' tells a specific OS how to control a specific device; for example, a printer driver will take the OS's "print" command and send the appropriate signal to the printer.