systems software

• Types of systems software

  • Operating systems
  • Utility software
• Operating systems


  Provides a platform on which users can run programs
• Utility software


  Used to maintain the computer systems
• Graphical user interface (GUI)


  • Windows, icons, menus, pointers (WIMP)
  • Visual
  • Interactive
  • Intuitive
  • Optimised for mouse and touch gesture output
• Command line


  • Text based
  • Less resource heavy compared to a GUI
  • More commands than a GUI
  • Efficient
  • For advanced users
  • Useful for automating processes with scripts
• Menu


  • Successive menus presented to the user
  • Single options chosen at each stage
  • Often with buttons on a keypad
• Natural language


  • Responds to questions in spoken language
  • Not always reliable
  • Getting better all the time
• Multitasking Software


  • Running multiple applications at the same time by giving each application a small time-slice of processor time
  • Allows more than one program to be held in memory at a time, and data shared between them such as a copy and paste
  • Enabled you to listen to music on your PC at the same time as word processing
• Memory Management


  • When programs are loaded, the operating system decides where they are held in memory
  • Over time the memory becomes fragmented as programs are loaded and closed because they use different amounts of memory
  • The operating system must keep track of different program fragments
  • When the memory is full, the operating system uses virtual memory
• Device drivers


  • Translates operating system instructions into commands that the hardware will understand
  • Each peripheral needs a device driver
  • Many are already built into the operating system
• Encryption


  • Encryption utilities use an algorithm to scramble plain text into cipher text
  • The text can only be decrypted and made readable again with a key
• Defragmentation


  • Defragmentation utilities reorganise files on a hard disk, putting fragments of files back together and it collects free space
  • This reduces movement of a read/write head across the surface of the disk which speeds up file access
  • Solid state drivers should not be fragmented as they have no moving parts and it is unnecessary and reduces their lifespan
• Data compression


  • Compression utilities reduce the size of a file so that it takes up less space and is quicker to download over the internet
  • Compressed files must be extracted before they can be read
  • Depending on the algorithm used, data is either lost, reducing the quality of an image or sound e.g. JPEG, or represented in a different way using binary, retaining the original data in a new and compressed format e.g. zip
• Open source vs Proprietary software


  • Open source:
  • Users can modify and distribute the software
  • Can be installed on any number of computers
  • Support provided by the community
  • Users have access to the source code
  • May not be fully tested
  • Proprietary source:
  • Users cannot modify the software. Protected by Copyright Design and Patents Act
  • Usually paid for and licensed per user or per computer
  • Supported by developers
  • Users do not have access to the source code
  • Tested by developers prior to release. Although they may run beta programmes