1.5 - Systems software

• Systems software


  Software that controls the hardware inside the computer and provides an interface for users to interact with it
• Application software


  End-user programs that are designed to perform specific tasks
• Types of operating systems

  • Windows
  • macOS
  • Linux
  • Ubuntu
  • Android
  • iOS
• Operating system


  • Manages the hardware in a computer and provides an environment for applications to run
  • Essential to the function of any computer
• Functions controlled by the operating system


  • User interface
  • Memory management
  • Peripheral management
  • User management
  • File management
• Graphical user interface (GUI)


  Uses small icons to represent files, devices and applications and allows the user to interact by clicking, dragging or touching them
• Command line interface (CLI)


  Involves typing in all of the commands via a keyboard
• Natural language interfaces


  Allow the user to control some software and dictate text rather than needing to type it
• Multitasking


  Several applications being loaded into RAM and running simultaneously
• Peripheral


  Any hardware component that is not part of the CPU
• Device driver


  Programs that act as a translator to allow the CPU and the devices to communicate correctly
• Spooling


  Temporarily storing data in a buffer before sending it to an output device
• File management


  The operating system controls all of the different files on the system, such as documents and executable programs
• File permissions


  Control who can see or open a file, write to a file or edit it, and who can delete a file
• Utility software


  A collection of programs, each of which does a specific housekeeping task to help maintain a computer system
• Types of utility software

  • Encryption
  • Defragmentation
  • Data compression
• Encryption


  The scrambling of data into a form that cannot be understood if it is accessed by unauthorised users
• Modern operating systems have built-in encryption utilities that enable the user to encrypt specific files or entire drives
• It is especially important that sensitive data copied onto laptops and portable storage devices is encrypted as there is more likelihood that these devices could be lost or stolen
• Utility software


  A collection of programs each of which does a specific housekeeping task to help maintain a computer system
• Types of utility software

  • encryption
  • defragmentation
  • data compression
• Encryption software


  Used to encode data so that it cannot be understood if it is intercepted by unauthorised users. The encryption process uses an algorithm and key to transform the plaintext into ciphertext. The same software and key are needed to decrypt the data.
• It is possible to encrypt specific files or whole drives depending on what is needed. In addition, data on portable and removable storage devices should be encrypted.
• Defragmentation


  Over time, data on a hard drive becomes fragmented. Parts of a file are saved to different areas of the disk where there is free space. This slows down the computer as more disk accesses are needed to read all of a file. Defragmentation software reorganises the files, putting all of the free space together and all of the parts of the same file together. This improves performance.
• There is no need to perform defragmentation on solid-state drives (SSDs) as they do not have any moving parts and so having data split up around the memory locations does not affect the read/write times. In fact, because SSDs have a limited number of read/write cycles, performing defragmentation is likely to reduce the life of an SSD.
• Data compression


  Uses algorithms to reduce the size of files so that they take up less storage space. There are two types of compression known as lossy and lossless. Compression is useful in freeing up storage space. It is also useful when transferring files across a network as smaller files require less bandwidth.
• Lossy compression


  Reduces the file size by deleting some of the data. It can be used on items such as photographs where the loss in detail will not be noticeable. As the data is completely removed from the file it can never be restored back to its original form.
• Lossless compression


  Must be used if a file, such as a text file or document, needs to be restored exactly back to its original form. Lossless compression uses algorithms to look for patterns and repeated elements in a file. These are then stored in a dictionary from where they can be referenced by a number. This enables data to be compressed and then restored to its original form.