The Purpose & Functionality of Operating Systems (AQA GCSE Computer Science)

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The Purpose & Functionality of Operating Systems

  • System software can be further broken down in to two categories, operating system and utility software

system-software

What is an operating system?

  • An operating system (OS) is software that provides an interface between the user and the hardware in a computer system

  • An operating system hides the complexities of the hardware from the user, for example:

    • A user does not need to know 'where' on secondary storage data is kept, just that it is saved for when they want it again

  • An operating systems main functions can be divided in to five key areas:

    • Provide a user interface

    • Memory & processor management

    • I/O management & device drivers

    • Application & security management

    • File management

User Interface

What is a user interface?

  • A user interface is how the user interacts with the operating system

  • Examples of user interfaces include:

    • Command Line Interface (CLI)

    • Graphical User Interface (GUI)

    • Menu

    • Natural language (NLI)

purpose-and-functionality-of-the-os-

What is a command line interface?

  • A Command Line Interface (CLI) requires users to interact with the operating system using text based commands

  • CLIs are more commonly used by advanced users

  • Examples of CLIs are MSDOS (Microsoft Disk Operating System) and Raspbian (for Raspberry Pi)

What is a graphical user interface?

  • A Graphical User Interface (GUI) requires users to interact with the operating system using visual elements such as windows, icons, menus & pointers (WIMP)

  • GUIs are optimised for mouse and touch gesture input

  • Examples of GUIs are Windows, Android and MAC OS

What is a menu interface?

  • A menu interface is successive menus presented to a user with a single option at each stage

  • Often performed with buttons or a keypad

  • Examples include

    • Chip and pin machines

    • Vending machines

    • Entertainment streaming services

What is a natural language interface?

  • A natural language interface (NLI) uses the spoken word to respond to spoken or textual inputs from a user

  • Examples include

    • Virtual assistants - Amazon Alexa, Google Assistant, Siri

    • Search engines

    • Smart home devices

Advantages and disadvantages of user interfaces

Interface

Advantages

Disadvantages

Command line (CLI)

  • Uses less system resources

  • Useful for automation of tasks

  • Commands are often faster to type than navigating menus

  • Requires users to remember commands

  • Typing errors are common

  • Less intuitive than GUI

Graphical (GUI)

  • Intuitive and user-friendly

  • Requires no previous knowledge to use

  • Information is visual, making it easier to understand

  • Uses more system resources

  • Can be slower to find and execute commands

  • Can be frustrating when doing repetitive tasks

Menu

  • Simplicity

  • Efficiency

  • Limited flexibility

  • Accessibility issues

Natural language (NLI)

  • Can be used by people with disabilities

  • Intuitive

  • Not always reliable

  • Privacy concerns

Memory & Processor Management

What is memory management?

  • Memory management is a process carried out by the operating system allocating main memory (RAM) between different programs that are open at the same time

  • The OS is responsible for copying programs and data from secondary to primary storage as it is needed

  • Programs and data require different amounts of RAM to operate efficiently and the OS manages this process

  • RAM is allocated based on priority and fairness, for example, system applications (essential) may have a higher priority than user applications

  • The OS dynamically manages the memory, adjusting allocation as needed to maintain optimal system performance

  • Memory management makes multitasking possible

What is processor management?

  • Processor management is a process carried out by the operating system dividing time (time slicing) in to small chunks and allocating them to different programs

  • The CPU can only execute one instruction at a time, it can can execute billions of them in one second.

  • The OS decides what programs get access to the CPU to give a user the perception of being able to use multiple programs at the same time (multitasking)

Peripheral Management & Device Drivers

What is I/O management?

  • Input/output (I/O) management is a process carried out by the operating system managing the way input and output devices interact with software

  • The OS allocates system resources to inputs/outputs to ensure efficient operation

  • I/O management makes plug-and-play (PnP) functionality possible, automatically detecting and configuring new inputs/outputs without the need for manually installing device drivers or power cycling the system

What is a device driver?

  • A device driver is a piece of software used to control a piece of hardware

  • Inputs/outputs require device drivers in order to be used by the operating system

  • The OS has generic device drivers built in which makes basic compatibility possible and enables plug-and-play (PnP)

  • In order for hardware to be used to its maximum capacity, often a separate device driver must be downloaded from the manufacturer

  • Device drivers are OS specific and are regularly updated

Application & Security Management

What is application management?

  • Application management is a process carried out by the operating that enables applications to talk directly to hardware and software through the use of application programming interfaces (APIs)

  • The APIs provide a standardised way for applications to access system resources

What is security management?

  • Security management is a process carried out by the operating system enabling different users to log onto a computer

  • A system administrator is able to allocate different access rights for different users on a network

  • The OS is able to maintain settings for individual users, such as desktop backgrounds, icons and colour schemes

  • The OS audits (keeps a log of) files created by users, accesses, edits and deletes  

File Management

What is file management?

  • File management is a process carried out by the operating system creating, organising, manipulating and accessing files and folders on a computer system

  • The OS manages where data is stored in both primary and secondary storage

  • File management gives the user the ability to:

    • Create files/folders

    • Name files/folders

    • Rename files/folders

    • Copy files/folders

    • Move files/folders

    • Delete files/folders

  • The OS allows users to control who can access, modify and delete files/folders (permissions)

  • The OS provides a search facility to find specific files based on various criteria

Worked Example

State four functions of an operating system [4]

How to answer this question

  • What does an operating system MANAGE?

Answer

  • Memory management

  • I/O device management

  • File management

  • Application management

  • Security management

  • Network management

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