What is the purpose of operating system in a computer?

Operating Systems

Operating Systems

Definition: Operating System

An operating system is a low level piece of software that manages the computer’s hardware & software, and provides an interface between the user and the computer.

Most people use computers because they want to use application software(such as word processing, internet browsing) however these applications only work inside of an operating system environment. The operating system is the software that controls, manages and run all of the applications on the computer.

The functions of an operating system include:

• Loading a software interface for the user to interact with (usually a GUI or CLI)
• Managing hardware resources such as memory and devices
• User management
• authentication & security
• File management

When a user is using a computer they are either interacting directly with the operating system ( e.g. logging in to the computer) or via an application (e.g. saving a word processing document)

Multitasking

Multitasking

Most general use systems (e.g. desktops, laptops, tablets) allow multitasking, where most than one program is open at one time.

Advantages

Allows a combination of active and passive user interaction, e.g.:

• Type up a word processing document while listening to music.
• Editing images while burning files to an optical device (DVD / CD)
• Allows rapid switching between applications which can make the use more efficient.

Disadvantages

• Multiple open applications can slow down the computer, making it harder to use.
• Requires more physical resources (CPU power / memory) so uses more battery.
• Can offer unwanted distractions from the task at hand.

POST Checks

Power On Self Test (POST) Checks

When you turn on the computer, before it tries to boot up the operating system it performs a POST check to ensure that computer is ready to start.

The checks include:

• Are all components of the computer functioning correct, such as the RAM and the CPU
• Are the required components (such as a keyboard/mouse) connected
• Are primary storage devices listing on the boot order for the master boot record connected.

Post Boot-up Activities

Post Boot-up Activities

Once the computer has fully booted up and the user logged in, the computer continues to process a number of delayed post bootup activities.

These activities may include:

• Running a scheduled virus check
• Syncing files with a remote server
• Downloading software updates

Resources

This resource will explain how operating systems work, and note the differences between the Microsoft Windows, Mac and Linux operating systems.

What is an operating system?

An operating system is a program that acts as an interface between the computer user and computer hardware, and controls the execution of programs.

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The operating system’s job

The operating system (OS) manages all of the software and hardware on the computer. It performs basic tasks such as file, memory and process management, handling input and output, and controlling peripheral devices such as disk drives and printers.

Most of the time, there are several different computer programs running at the same time, and they all need to access your computer’s central processing unit (CPU), memory and storage. The operating system coordinates all of this to make sure each program gets what it needs.

In the image above the User interfaces with the System & Application software. The System & Application software interfaces with the Operating System. The Operating system interfaces with the Hardware. Each of these interfaces are two way transactions with each sending and receiving data.

Types of operating systems

Operating systems usually come pre-loaded on any computer you buy. Most individuals use the operating system that already comes with their computer however it is possible to upgrade or change the initial operating system to suit your preference.

Different operating systems will work in different ways. They may appear visually different, have different terms for common functions and organise programs in different ways. Do not be alarmed if you find yourself using a computer at university that you are unfamiliar with – a bit of practice and you’ll be well on your way!

There are many operating systems that are available however the three most common operating systems are Microsoft’s Windows, Apple’s macOS and Linux. In the table below, we will outline a few of the key differences between each system.

	Microsoft Windows	Mac OS	Linux
Pre-loaded Devices	Microsoft Windows is pre-loaded on all computers except Apple products.	Mac OS is the pre-loaded OS on all Apple Mac computers.	Linux is not pre-loaded on many computers, but is free to download.
Customisability	Minimal changes.	Minimal changes.	Highly customisable as it is open source. Huge collaborative community building a range of applications.
Icon	Windows icon. This is the Start Menu and is located in the bottom left hand corner of the screen it allows you to access your ‘Control Panel’, ‘Computer’, programs, folders and more. You can also shut down your computer using this menu.	Apple icon. It is located in the top left hand corner of the screen and it is where you can access your ‘System Preferences’, ‘Software Update’, ‘About This Mac’ and more. You can also shut down your computer using this menu.	Different icons depending on what software interface you are using e.g. Redhat has a redhat symbol. Ubuntu has the Circle of Friends symbol. These symbols are located in the top left hand corner of the screen and it is where you can access all your computer applications.
Search Tool	Magnifying glass located in the Start Menu.	Magnifying glass located in the top right hand corner.	If using Ubuntu, click on the Circle of Friends icon.
Task Bar	Located at the bottom of the screen. It contains shortcuts to applications, the date and time, and more.	Located at the bottom of the screen. It contains shortcuts to applications, files and folders. Referred to as a ‘Dock’.	Located on the left hand side of the screen with applications running in a vertical manner. It contains shortcuts to applications, files and folders.
Finding Programs	Start Menu. An application where you can view and organise files and folders.	Finder. An application where you can view and organise files and folders.	Dash. The dashboard of Ubuntu where you can view all applications and files.
Default Browser	Internet Explorer. (Now known as Microsoft Edge for Microsoft Windows 10 version and later)	Safari.	Firefox.