systems software

• Operating System (OS)


  Software that helps to manage the resources of a computer system and provide the interface between the user and the computer's hardware
• Main functions of an operating system


  • Memory Management & Multitasking
  • Peripherals Management & Drivers
  • User Management
  • File Management
  • User Interface
• Memory Management & Multitasking


  1. Programs must be temporarily stored in RAM for the CPU to process them

  2. OS transfers programs in and out of memory from the hard drive (or virtual memory) when processing is required

  3. Programs are removed from RAM when closed to free up space for other tasks

  4. OS can only perform one process at a time, but through memory management it can appear that more than one process is being executed - this is called multitasking
• Peripheral


  External device connected to a computer system to input or output data
• Device driver


  Program that provides an interface for the OS to interact and communicate with an external device
• Device drivers


  • Hardware dependent
  • OS-specific
  • Translate the OS' instructions into a format the specific hardware can understand
• Buffer


  Used to temporarily store data until it can be processed, as the CPU and the peripheral will process data at different speeds
• User management


  • OS allows users to create, manage and delete individual accounts
  • User accounts can be granted different access rights such as an administrator or guest
  • OS will manage security settings such as allowing passwords to be reset and can also be used to monitor login activity
• File management


  • OS creates and maintains a logical management system to organise files and directories (folders)
  • Allows files to be named, renamed, opened, copied, moved, saved, searched for, sorted and deleted
  • Allows users to set access rights for specific files and to view file properties
• User interface


  Final function of an operating system, allowing a human to interact with the computer system
• Human-computer interaction (HCI)


  The way in which a user can navigate a computer system
• Types of user interface


  • Graphical User Interface (GUI)
  • Command-Line Interface
  • Menu-Driven Interface
  • Touch-Sensitive Interface
  • Voice-Driven Interface
• Graphical User Interface (GUI)


  • Icons displayed to represent shortcuts to applications and files
  • Multiple windows can be opened at the same time and switched between
  • Folder and file system displayed and manipulated allowing for copying, searching, sorting and deleting data
  • Interface can be customised, such as changing font sizes and the desktop background
  • Taskbar allows shortcuts to be pinned for quick access
  • Menus can be opened from the Start button to display files and shortcuts
  • System settings can be accessed such as network and hardware options
• Command-Line Interface


  • Entirely text-based
  • Requires users to interact with the system by typing commands
  • Complicated process, mistakes could easily accidentally delete data
  • Many commands to learn, only experts who have been trained will be able to efficiently make use of it
• Menu-Driven Interface


  • Displays data in a series of linked menus
  • User friendly and easy to use as commands do not need to be memorised
  • Can be annoying to find specific data through a large number of menus without a search feature
• Touch-Sensitive Interface


  • Human interacts with the device by pressing on a touchscreen
  • Very intuitive and suitable for most users without training
  • May not work with dirty or wet fingers
  • Will take longer to write text compared to using a keyboard
• Voice-Driven Interface


  • Controlled by speaking commands aloud to a listening device
  • Intuitive, can be used hands-free and helps to speed up processes
  • Commands may be misheard or limited in what can be performed
• Utility software


  Dedicated programs used for the maintenance and organisation of a computer system (this is known as 'housekeeping')
• Utility software


  • Required to run additional tasks not performed by the operating system
  • Examples include anti-malware, firewall, encryption, data compression, backup, disk checkers, disk formatters, auto-updaters
• Fragmentation


  When a file is split into parts that are saved in different storage locations on a hard disk drive due to limited contiguous space
• Defragmentation


  1. Empty spaces are collected together on the hard disk drive

  2. File fragments are moved to be stored together