Operating System is a collection of special programs, which directly controls the computer. Its main purpose is to increase the efficiency of the computer system.


  1. The first program that loads on a computer when we switch it on is called its operating system.
  2. It is a program that acts as an interface between the software and computer hardware.
  3. It is a specialised set of programs that manages the overall functioning of the computer and its resources.
  4. It controls and monitors the execution of other programs and applications.


Functions:

Functions of an operating system are as follows: -


1. Processor Management –

Operating System manages the working of a processor by allocating various jobs to it. It ensures that each process and application receives enough time by the processor to function properly.


2. Memory Management –

Operating system manages the sharing of the internal memory (RAM, Cache etc.) among the multiple applications to ensure the proper execution of every process.


3. Device Management –

Operating System controls the working of all input and output (I/O) devices. It receives  the request from these devices, performs the specific tasks, and communicate back to the requesting processor.


4. File Management –

Operating System keeps a track of the information regarding the creation, deletion, transfer, copy, and storage of files in an organised way. It also maintains the integrity of the data stored in those files, including directory structure.


5. Security –

Operating system provides various techniques that ensure the integrity and confidentiality of the user data. It is done using passwords, usernames, and firewall.


6. Error Detection –

Operating System checks the system time to time from any kind of external threat or malicious software activity. It also checks the hardware for any type of damage, and displays appropriate alerts to the users.


7. Job Scheduling –

In a multi-tasking operating system where multiple programs run at the same time, the operating system determines which application should run and in what order. It also checks how much time should be allocated to each application.


Types of Operating System:

Various types of operating system are as follows: -


1. Single User Operating System –

This operating system could support only one user to do one thing at a time. The most popular single user operating system includes Microsoft Windows 95 and Microsoft DOS.


2. Graphical User Interface –

It is graphic based, interactive in nature. In graphical user interface, menus and icons are available to perform all operations just by clicking on them.

Examples include: Windows OS, Mac OS, Linux etc.


3. Multi User Operating System –

A multi-user operating system (OS) is designed to allow multiple users to access and operate a single computer system simultaneously, often connecting through networked terminals or other devices. It manages system resources and handles requests from each user, ensuring individual accounts and data privacy through security features like authentication and access control. 

Examples include: Unix, Linux, MacOS, and Windows Server.


4. Multi User Multi-Tasking Operating System –

A multi-user multitasking operating system is a system that allows multiple users to log in and use its resources simultaneously, while also enabling a single user to run multiple programs or tasks at the same time.

Examples include: Windows, MacOS, Linux.


5. Multi-Threading Operating System –

A multi-threading operating system allows multiple threads (independent flows of execution) to run concurrently within a single process, improving performance and responsiveness by efficiently utilizing multi-core processors. Threads within a process share resources like memory and code, making context switching faster than with multiple separate processes. This capability is crucial for modern applications like web servers, financial systems, and games, enabling them to handle multiple requests and perform background tasks simultaneously. 


6. Real Time Operating System –

It is designed to handle rea life scenario and problems. Such operating system have the capability to prioritise the process, minimise the execution time and work independently.

For eg.: whenever we book an air ticket, we are actually communicating with a real time operating system.


7. Distributed Operating System –

It runs on the computer that are located in different geographical areas, interconnected through a network. It controls these interconnected systems and makes them appear to be a single computer. It allows all the linked devices to access the data, software, and process tasks over a network of geographically widespread computers.


8. Batch Operating System –

In this operating system, to speed up processing jobs with similar needs are batched together and run as a group. The programmers leave their programs with the operator then sorts the programs with similar requirements into batches.


There are certain problems with Batch Operating System such as:

  1. Lack of interaction between the user and the job.
  2. CPU is often idle, because the speed of the mechanical Input/Output devices is slower than the CPU.
  3. Difficult to provide the desired priority.