1.5.1 - Operating systems

A system software that allows the user to interact with the hardware by providing an interface between the user and the hardware and allows applications to run.

• User interface • Memory management and multitasking • Peripheral management and drivers • User management • File management

A user interface allows the user to interact with the computer and communicate with the hardware. mark scheme bits: * Outputting data to the user * Receiving input from the user * Allows user to communicate/interact with/control the computer * Creating/displaying/allowing interaction with a GUI/command prompt interface

• Graphical user interface (GUI) • Command line interface (CLI)

• Graphical User Interface • Visual systems that let users interact with digital devices through graphical icons and visual elements and buttons. • has windows, icons, menus and pointers (WIMP)

• user friendly • clear visual elements so users can quickly learn how to interact with devices and software • accessibility and easy to use • improves efficiency and speeds up tasks by providing tools like shortcuts, menus, and toolbars

• takes up a large space on a hard disk drive • uses more processing power in comparison to other interfaces • needs significantly more RAM to run successfully

• Command Line Interface • A means of interacting with computer software and systems using commands, mainly keyboard strokes.

• If the user knows the correct commands then this type of interface can be much faster • much less RAM used • low resolution, cheaper monitor can be used

• can be very confusing if new to using command line interfaces • commands have to be typed very precisely therefore any errors (like spelling) would cause command to fail • lots of commands needed to be learnt.

• Manages use of RAM by allocating and deallocating memory to programs as it is needed. • Manages use of RAM by allocating and deallocating memory to programs as it is needed. (uses VM too) • Transfers data between memory and CPU > Moves instructions into RAM before execution > allocates memory to applications > each program gets the RAM it needs > prevents programs overwriting each other • Over time, the memory becomes fragmented as programs are loaded and closed because they all require different amounts of memory space. • Allows for multitasking as more than one program to be held in memory at the same time (several programs appear to be in use at the same time) because the OS rapidly switches between tasks.

• Peripherals are external hardware devices which can be connected to the computer. • Peripheral management is when the OS manages communication between peripherals and the processor. • This is done using device drivers. • Device drivers are small programs which translate operating system instructions into hardware signals which a specific peripheral will understand. • without drivers, hardware is be unable to communicate with the operating system or work effectively. mark scheme bits: *Receiving data from input devices * Transmitting data to output devices * Installing/downloading device drivers * Allows communication from input device / to output device

• Managing user permissions, accounts and access levels on an operating system. • Managing user permissions, accounts and access levels on an operating system. • functions include: personal account allocation, admin control of user access levels and security (like passwords) in order to protect files and data. • The OS stores user profiles, data, and downloads, and controls each user’s access to files and programs.

• The function that the operating system uses to organise and keep track of files on a computer system. (data is stored in files) • features include: naming files, allocating files to folders, saving, deleting, moving, copying files (+etc)