Responsive image

2.4 - Operating Systems

Operating Systems

What are Operating Systems?

An operating system (OS) is a collection of software that manages computer hardware resources and provides common services for computer programs. The operating system is a vital component of the system software in a computer system.

An Operating System (OS) is an interface between a computer user and computer hardware. An operating system is a software which performs all the basic tasks like file management, memory management, process management, handling input and output, and controlling peripheral devices such as disk drives and printers.

In any computer, the operating system:

  • Manages memory usage between programs
  • Controls the backing store and peripherals such as scanners and printers
  • Deals with the transfer of programs in and out of memory
  • Organises processing time between programs and users
  • Maintains security and access rights of users
  • Deals with errors and user instructions
  • Allows the user to save files to a backing store
  • Provides the interface between the user and the computer - for example, Windows Vista and Apple OSX.
  • Issues simple error messages.

In a larger computer such as a mainframe the operating system works on the same principles.

Memory Management

Memory management refers to management of Primary Memory or Main Memory. Main memory is a large array of words or bytes where each word or byte has its own address.

Main memory provides a fast storage that can be accessed directly by the CPU. For a program to be executed, it must in the main memory. An Operating System does the following activities for memory management:

  • Keeps tracks of primary memory, i.e., what part of it are in use by whom, what part are not in use
  • In multiprogramming, the OS decides which process will get memory when and how much
  • Allocates the memory when a process requests it to do so
  • De-allocates the memory when a process no longer needs it or has been terminated

Processor Management

In multiprogramming environment, the OS decides which process gets the processor when and for how much time. This function is called process scheduling. An Operating System does the following activities for processor management:

  • Keeps tracks of processor and status of process. The program responsible for this task is known as traffic controller
  • Allocates the processor (CPU) to a process
  • De-allocates processor when a process is no longer required

Device Management

An Operating System manages device communication via their respective drivers. It does the following activities for device management −

  • Keeps tracks of all devices. Program responsible for this task is known as the I/O controller.
  • Decides which process gets the device when and for how much time.
  • Allocates the device in the efficient way.
  • De-allocates devices.

File Management

A file system is normally organized into directories for easy navigation and usage. These directories may contain files and other directions.

An Operating System does the following activities for file management −

  • Keeps track of information, location, uses, status etc. The collective facilities are often known as file system.
  • Decides who gets the resources.
  • Allocates the resources.
  • De-allocates the resources.

Other Important Activities

Following are some of the important activities that an Operating System performs −

  • Security − By means of password and similar other techniques, it prevents unauthorized access to programs and data.
  • Control over system performance − Recording delays between request for a service and response from the system.
  • Job accounting − Keeping track of time and resources used by various jobs and users.
  • Error detecting aids − Production of dumps, traces, error messages, and other debugging and error detecting aids.
  • Coordination between other softwares and users − Coordination and assignment of compilers, interpreters, assemblers and other software to the various users of the computer systems.

Types of Operating Systems

Operating systems usually come pre-loaded on any computer you buy. Most people use the operating system that comes with their computer, but it's possible to upgrade or even change operating systems. The three most common operating systems for personal computers are Microsoft Windows, Mac OS X, and Linux.

Modern operating systems use a graphical user interface, or GUI (pronounced gooey). A GUI lets you use your mouse to click icons, buttons, and menus, and everything is clearly displayed on the screen using a combination of graphics and text.

the windows GUI

Each operating system's GUI has a different look and feel, so if you switch to a different operating system it may seem unfamiliar at first. However, modern operating systems are designed to be easy to use, and most of the basic principles are the same.

Microsoft Windows

Microsoft created the Windows operating system in the mid-1980s. Over the years, there have been many different versions of Windows, but the most recent ones are Windows 10 (released in 2015), Windows 8 (2012), Windows 7 (2009), and Windows Vista (2007). Windows comes pre-loaded on most new PCs, which helps to make it the most popular operating system in the world.

Windows 7

Check out our tutorials on Windows Basics and specific Windows versions for more information.

Mac OS X

Mac OS is a line of operating systems created by Apple. It comes preloaded on all new Macintosh computers, or Macs. All of the recent versions are known as OS X (pronounced O-S Ten), and the specific versions include El Capitan (released in 2015), Yosemite (2014), Mavericks (2013), Mountain Lion (2012), and Lion (2011).

According to StatCounter Global Stats, Mac OS X users account for less than 10% of global operating systems—much lower than the percentage of Windows users (more than 80%). One reason for this is that Apple computers tend to be more expensive. However, many people do prefer the look and feel of Mac OS X over Windows.

Mac OS X Lion

Check out our tutorials on OS X Basics and specific OS X versions for more information.


Linux (pronounced LINN-ux) is a family of open-source operating systems, which means they can be modified and distributed by anyone around the world. This is different from proprietary software like Windows, which can only be modified by the company that owns it. The advantages of Linux are that it is free, and there are many different distributions- or versions - you can choose from.

According to StatCounter Global Stats, Linux users account for less than 2% of global operating systems. However, most servers run Linux because it's relatively easy to customize.

Ubuntu Linux

To learn more about different distributions of Linux, visit the Ubuntu, Linux Mint, and Fedora websites, or refer to our Linux Mint Resources. For a more comprehensive list, you can visit MakeUseOf's list of The Best Linux Distributions.

Operating systems for mobile devices

The operating systems we've been talking about so far were designed to run on desktop and laptop computers. Mobile devices such as phones, tablet computers, and MP3 players are different from desktop and laptop computers, so they run operating systems that are designed specifically for mobile devices. Examples of mobile operating systems include Apple iOS and Google Android . In the screenshot below, you can see iOS running on an iPad.

screenshot of Apple iOS running on iPad

Operating systems for mobile devices generally aren't as fully featured as those made for desktop and laptop computers, and they aren't able to run all of the same software. However, you can still do a lot of things with them, like watch movies, browse the Web, manage your calendar, and play games.

Task - 1

Single User and Multi-User Operating systems:

  1. Describe single user, single application and single user, multi-tasking operating systems, give examples of each type.
  2. Discuss the key differences between single user and Multi-User Operating systems .

Task - 2

Single processor/multiprocessor operating systems:

  1. Where are single processor operating systems primarily used and give some examples of them.
  2. Where are multiprocessor operating systems mainly used? Give some examples of the most popular types.

Task - 3

Types of operating systems:

Give examples of each of the following types of operating systems:

  1. Off the shelf
  2. Open Source
  3. Bespoke

  • Learning Objectives

  • I can explain the purpose of single user/multiuser operating systems
  • I can explain the purpose of single processor/multiprocessor operating systems
  • I can explain the purpose of off the shelf/open source/bespoke operating systems