What is meant by the operating system?

A software interface between the user and device hardware is known as an operating system (OS). Every device needs to have at least one operating system to run its programs. Both the application and program are managed by the operating system.

Example: Mac OS X, Unix, Microsoft Windows, etc.

Why do we need an operating system?

The purpose of the operating systems is to switch the CPU between applications, store various types of files, manage memory, and interact with peripheral devices. The most important program of a computer system is the operating system. It allows the system to run and execute programs.

Functions of operating system

The functions of OS are listed below.

• Process management: OS is responsible for process creation, scheduling the process for execution, process synchronization in the case of concurrent execution and process termination.
• File management: OS performs all file management activities such as file creation, retrieval, storage, sharing, file protection and naming.
• Memory management: Memory management involves allocation and de-allocation of memory space to programs in need of these resources.
• Device management: OS keeps track of all the devices. It is responsible for managing the input/output (I/O) operations and it performs device de-allocation and allocation.

Types of operating system

The following are the types of operating systems:

Batch OS

Some computer processes are time-consuming and lengthy. To speed up those processes, they can be grouped together and executed at once. The batch operating system is responsible for execution of jobs in batches. In such systems, there is little interaction between the user and the system. Example: Backup operation.

Advantages

• Useful for multiple users.
• Efficiently manages large workloads.

Disadvantages

• Debugging is quite hard.
• Costly to install and maintain.

Multitasking OS

The other name of multitasking OS is time-sharing OS. In time-sharing OS, each task is executed for a fixed duration of time known as time slice or quanta. This system allows multiple users to work simultaneously. The users share the Central Processing Unit (CPU) time. The response time is minimized by distributing the access of the users to various terminals. Example: UNIX.

Advantages

• The execution time is equal for each task.
• The processor’s idle time is reduced.

Disadvantages

• Data communication is quite difficult.
• Data security is not assured.

Real-time OS

Real-time OS supports a real-time system. The system must be able to respond without any delay since delay will cause loss of property or life. Example: Air traffic control system, multimedia systems.

Real-time OS is classified into two types, which are hard real-time or soft real-time systems. A real-time system is installed in the application where the time constraint is very strict. These systems are used in equipment like airbags and parachutes. A soft real-time system is installed in the application where the time requirement is not very strict. A critical task can get priority over the other tasks. These systems are used in reservation systems.

Advantages

• Provides quick response.
• Capable of handling multiple external events.

Disadvantages

• Uses complex algorithm which is quite hard to understand.
• System resources are used heavily.

Distributed OS

In distributed OS, a single communication channel is used to connect several computers. A loosely coupled system is where the independent computers will have their own Central Processing Unit (CPU) and memory unit. The processes in the system are of different sizes and perform different functions. Using distributed OS, users can access the files in the connected system. Example: Locus.

Advantages

• Faster data exchange.
• Delay during data processing is reduced.

Disadvantages

• Expensive to install.
• Failure of primary network might lead to failure of entire system.

Network OS

The other name of network OS is a tightly coupled system. Network OS runs on the server and manages the networking functions like security, real-time data transfer etc. It allows sharing files, printers, security, and other functions using a computer network like Local Area Network (LAN) or any private network. Example: LINUX.

Advantages

• Remote server access is possible.
• High stability is provided for the centralized servers.

Disadvantages

• Servers are expensive.
• Requires to update and maintain regularly.

Commonly used operating system

The following are the commonly used operating systems,

Microsoft Windows

Microsoft Windows is a popular OS for both the office and home computer systems, which is developed by Microsoft. Windows initial version has worked along with the Microsoft OS called MS-DOS. It is more compatible with other software. Most of the programs run on Microsoft Windows as it is developed by Microsoft. Windows is proprietary software (the company develop, design, and sell their own OS).

Apple iOS

While comparing Android, a commercial operating system for smartphones is Apple iOS. This OS usually runs on apple hardware like iPhone, iPod, and iPad tablets. The iOS feature includes the app store, where the user can download free software and applications. App stores provide more importance to security, which includes encryption to check unauthorized users. The Apple iOS feature includes FaceTime and Siri.

Google Android

Android is a popular OS, which is developed by Google and is mostly used in smartphones and tablets. Compared to iOS, this can be used on the device with different manufactures. A huge portion of google android is open source, where the user can easily download a custom version. Similar to iOS, Android has a media store known as the play store which helps to download applications.

Apple Mac OS

The Mac OS is the successor of OS X, which works in apple desktops and laptops. Mac OS shares certain features with Unix-related OS like Linux and the features and applications are user-friendly including voice-personal assistant (Siri) and video-calling (FaceTime). Mac OS is an example of a proprietary OS.

Linux OS

Linux is an open-source OS. Linux is popular among corporate servers and programmers. Linux distributions usually provide tools and a custom user interface for software installation. Linux runs on various hardware which is freely available over the internet. 

Context and Applications

This topic is important for postgraduate and undergraduate courses, particularly for,

• Bachelors in Computer Science Engineering.
• Associate of Science in Computer Science.

Practice Problems

Question 1: _____ OS allows multiple users to perform the work simultaneously.

1. Batch OS
2. Multitasking OS
3. Network OS
4. Mobile OS

Answer: Option b is correct.

Explanation: The other name of multitasking OS is time-sharing OS. This system allows multiple users to perform the work in the system simultaneously. In this OS, each task is given some time so that all the tasks can work efficiently.  The users share the Central Processing Unit(CPU) time.

Question 2: _____ is not an operating system.

1. Windows 10
2. Linux
3. Unix
4. Oracle

Answer: Option d is correct.

Explanation: Oracle is the database for enterprise grid computing. Oracle is also known as Oracle DB, Oracle, or Oracle Database. Windows, Linux, and Unix are the various types of OS.

Question 3: OS provides a user-friendly interface known as ___.

1. GUI
2. CPU
3. Embedded system
4. Application

Answer: Option a is correct.

Explanation: Operating system is simple to use with Graphical User Interface(GUI) and a user-friendly interface provided by OS. GUI is an interface used by the Windows OS.

Question 4: Network OS runs on ____.

1. Server
2. Embedded system
3. Application program
4. None of the above

Answer: Option a is correct.

Explanation: A network OS runs on the server and manages the networking functions like security, data, application, etc. It allows sharing files, printers, security, and other functions using a computer network like LAN or any private network.

Question 5: Time-sharing OS is used by multiple users to share ___ time.

1. CPU
2. Response
3. Inter-process
4. None of the above

Answer: Option a is correct.

Explanation: Time-sharing OS is used to share the CPU time by multiple users. The time-sharing system allows multiple users to perform the work in the system simultaneously.