Functions of Operating System

An operating system has three main functions:

(1) manage the computer's resources, such as the central processing unit, memory, disk drives, and printers.

(2) establish a user interface.

(3) execute and provide services for applications software.

Operating System supports the basic functions of the computer and is a low-level software. The functions of operating systems are as described below:

i)  I/O Management:

OS manages I/O devices and makes the I/O process effective. OS accepts the input from the input device, stores it in the main memory, ask the CPU to process it and finally provides the result to the output devices for output.

ii) Command Interpreter:

Command interpreter is one of the part of operating system which reads the commands that user types in at a terminal, interprets them and translate them into a detailed set of instructions that the computer hardware can understand. It varies widely from one OS to other OS. Every OS must provide command interpreter for its operation.

iii) Memory Management:

Memory is the large array of words or bytes, each with its own address. When user requests CPU for read/write operation, OS determines the amount of memory required for the program instructions and data. Then, OS allocates required memory to load the program and data into RAM. When program terminates its memory area is free and the same memory area is allocated for other programs.

iv)  Process Management:

OS finds the status of processor and processes, chooses a job, chooses processer in the job, allocates the processor to the process and frees the processor when the process is executed.

v)  Time Sharing:

OS manages the time of CPU. The kernel OS checks frequency for other processes requesting CPU time. Time-sharing checks for CPU request from higher priority processes that are made every 10 milliseconds. When two or more processes at the same priority level are competing for the CPU time, CPU time is sliced into segments, defined by time slice and passed from process to process in a round robin fashion, preventing a single process from monopolizing the CPU until it blocks or terminates.

vi)  Security:

OS makes sure that only authorized users get access to the computer and its data and the users only do things they are authorized to do.

vii) Deadlock Prevention:

During processing, a situation can arise in which a resource shared by two or more processes cannot continue because the resource required by one process is held by the other. This situation is called deadlock. OS ensures that the above condition do not hold by carefully allocating resources.

viii)  Interrupt Handling:

Interrupt is a signal generated from a device or program when they need attention of the CPU. OS determines the type of interrupt and priority of the interrupt, stops the execution process of CPU, preserves the initial state of the CPU, perform the requested operation and brings the CPU at the same state when it was stopped.

ix) Virtual Storage:

If there are programs larger than main memory (RAM) of the computer, OS uses the reserved space in the secondary memory which is termed as virtual memory. It makes the execution of larger program (than RAM) possible but at the same times the operation becomes slower.

Features of Operating System (OS)

Here is a list important features of OS:

• Protected and supervisor mode
• Allows disk access and file systems Device drivers Networking Security
• Program Execution
• Memory management Virtual Memory Multitasking
• Handling I/O operations
• Manipulation of the file system
• Error Detection and handling
• Resource allocation
• Information and Resource Protection

 

 

Basics of computer

A computer is a machine that can be instructed to carry out sequences of arithmetic or logical operations automatically via computer programming. Modern computers have the ability to follow generalized sets of operations, called programs. These programs enable computers to perform an extremely wide range of tasks. A "complete" computer including the hardware, the operating system (main software), and peripheral equipment required and used for "full" operation can be referred to as a computer system. This term may as well be used for a group of computers that are connected and work together, in particular a computer network or computer cluster.

Computers are used as control system for a wide variety of industrial and consumer devices. This includes simple special purpose devices like microwave oven and remote contols, factory devices such as industrial robots and computer-aided design, and also general purpose devices like persnol computer and mobile devices such as smartphones. The Internet is run on computers and it connects hundreds of millions of other computers and their users.

Characteristics of Computer

1. Speed: – As you know computer can work very fast. It takes only few seconds for calculations that we take hours to complete. You will be surprised to know that computer can perform millions (1,000,000) of instructions and even more per second.

Therefore, we determine the speed of computer in terms of microsecond (10-6 part of a second) or nanosecond (10 to the power -9 part of a second). From this you can imagine how fast your computer performs work.

2. Accuracy: – The degree of accuracy of computer is very high and every calculation is performed with the same accuracy. The accuracy level is 7.

 

determined on the basis of design of computer. The errors in computer are due to human and inaccurate data.

3. Diligence: – A computer is free from tiredness, lack of concentration, fatigue, etc. It can work for hours without creating any error. If millions of calculations are to be performed, a computer will perform every calculation with the same accuracy. Due to this capability it overpowers human being in routine type of work.

4. Versatility: – It means the capacity to perform completely different type of work. You may use your computer to prepare payroll slips. Next moment you may use it for inventory management or to prepare electric bills.

5. Power of Remembering: – Computer has the power of storing any amount of information or data. Any information can be stored and recalled as long as you require it, for any numbers of years. It depends entirely upon you how much data you want to store in a computer and when to lose or retrieve these data.

 

6. No IQ: – Computer is a dumb machine and it cannot do any work without instruction from the user. It performs the instructions at tremendous speed and with accuracy. It is you to decide what you want to do and in what sequence. So a computer cannot take its own decision as you can. 

7. No Feeling: – It does not have feelings or emotion, taste, knowledge and experience. Thus it does not get tired even after long hours of work. It does not distinguish between users.

8. Storage: – The Computer has an in-built memory where it can store a large amount of data. You can also store data in secondary storage devices such as floppies, which can be kept outside your computer and can be carried to other computers.

Basic Parts of Computer

Computer case

The computer case is the metal and plastic box that contains the main components of the computer, including the motherboard, central processing unit (CPU), and power supply. The front of the case usually has an On/Off button and one or more optical drives.

Computer cases come in different shapes and sizes. A desktop case lies flat on a desk, and the monitor usually sits on top of it. A tower case is tall and sits next to the monitor or on the floor. All-in-one computers come with the internal components built into the monitor, which eliminates the need for a separate case.

Monitor

The monitor works with a video card, located inside the computer case, to display images and text on the screen. Most monitors have control buttons that allow you to change your monitor's display settings, and some monitors also have built-in speakers.

Newer monitors usually have LCD (liquid crystal display) or LED (light-emitting diode) displays. These can be made very thin, and they are often called flat-panel displays. Older monitors use CRT (cathode ray tube) displays. CRT monitors are much larger and heavier, and they take up more desk space.

Keyboard

The keyboard is one of the main ways to communicate with a computer. There are many different types of keyboards, but most are very similar and allow you to accomplish the same basic tasks.

Mouse

The mouse is another important tool for communicating with computers. Commonly known as a pointing device, it lets you point to objects on the screen, click on them, and move them.

There are two main mouse types: optical and mechanical. The optical mouse uses an electronic eye to detect movement and is easier to clean. The mechanical mouse uses a rolling ball to detect movement and requires regular cleaning to work properly.

Mouse alternatives

There are other devices that can do the same thing as a mouse. Many people find them easier to use, and they also require less desk space than a traditional mouse. The most common mouse alternatives are below.

• Trackball: A trackball has a ball that can rotate freely. Instead of moving the device like a mouse, you can roll the ball with your thumb to move the pointer.
• Touchpad: A touchpad—also called a trackpad—is a touch-sensitive pad that lets you control the pointer by making a drawing motion with your finger. Touchpads are common on laptop computers.

Advantages Of Computer

Computer has made a very vital impact on society. It has changed the way of life. The use of computer technology has affected every field of life. People are using computers to perform different tasks quickly and easily. The use of computers makes different task easier. It also saves time and effort and reduces the overall cost to complete a particular task.

Many organizations are using computers for keeping the records of their customers. Banks are using computers for maintaining accounts and managing financial transactions. The banks are also providing the facility of online banking. The customers can check their account balance from using the internet. They can also make financial transaction online. The transactions are handled easily and quickly with computerized systems.

People are using computers for paying their bills, managing their home budgets or simply having some break and watching a movie, listening to songs or playing computer games. Online services like skype or social media websites are used for communication and information sharing purposes.

Computer can be used as a great educational tool. Students can have access to all sort of information on the internet. Some great websites like Wikipedia, Khan’s Academy, Code Academy, Byte-Notes provides free resources for students & professionals. 

Disadvantages Of Computer

The use of computer has also created some problems in society which are as follows.

Unemployment

Different tasks are performed automatically by using computers. It reduces the need of people and increases unemployment in society.

Wastage Of Time And Energy

Many people use computers without positive purpose. They play games and chat for a long period of time. It causes wastage of time and energy. Young generation is now spending more time on the social media websites like Facebook, Twitter etc or texting their friends all night through smartphones which is bad for both studies and their health. And it also has adverse effects on the social life.

Data Security

The data stored on a computer can be accessed by unauthorized persons through networks. It has created serious problems for the data security.

Computer Crimes

People use the computer for negative activities. They hack the credit card numbers of the people and misuse them or they can steal important data from big organizations.

Privacy Violation

The computers are used to store personal data of the people. The privacy of a person can be violated if the personal and confidential records are not protected properly.

Health Risks

The improper and prolonged use of computer can results in injuries or disorders of hands, wrists, elbows, eyes, necks and back. The users can avoid health risks by using the computer in proper position. They must also take regular breaks while using the computer for longer period of time. It is recommended to take a couple of minutes break after 30 minutes of computer usage.

Impact On Environment

The computer manufacturing processes and computer waste are polluting the environment. The wasted parts of computer can release dangerous toxic materials. Green computer is a method to reduce the electricity consumed and environmental waste generated when using a computer. It includes recycling and regulating manufacturing processes. The used computers must be donated or disposed off properly.

Web browser

This is application software for browsing the web, viewing documents, managing web applications, and performing other tasks on the Internet. The browser processes user requests, sends them to a server, retrieves data from the server, and outputs them as web pages.

Browsers are distributed free of charge. Microsoft Edge comes as part of the Windows operating system. Mozilla Firefox - separately or as part of Linux distributions. Safari is available on Mac OS. Google Chrome, Opera, and many other browsers - as a standalone application, they are downloaded separately.

Browser functions

• Downloading of various files
• Storage of data (passwords, bookmarks for important resources, history of visits)
• Information exchange (e-mail, chats, forums, social networks)
• Online commerce
• Online education

Microsoft Office

This is a Microsoft Office application package for the Windows, Android, macOS, and iOS operating systems. It includes software for working with texts, spreadsheets, databases, images, etc.

At present, Microsoft provides the purchase of Office in several options:

1. Microsoft 365. Provides the right to use the latest versions of Microsoft Office applications, as well as a number of certain services (Exchange Online, OneDrive, Skype for Business, etc.) on a monthly or annual subscription basis. Users can choose the type of plan that is suitable for them:

• for home and family
• for business
• for enterprise
• for education.

The type of plan will determine what applications you will have on your computer.

2. Office 2021. Purchased as a lump sum and gives you the right to use the Office version in perpetuity. Microsoft regularly updates the Office package by adding new applications or special tools. However, if you buy a particular version of Microsoft Office, for example, 2021, you can't upgrade to the next version of Office for free. You must purchase the new version at full price to upgrade.

Microsoft office also provides several plan options:

• Office for home and study 2021
• Office for home and business 2021
• Office Professional 2021.

Composition

• Microsoft Word is a text editor. It allows you to work with documents of various complexity.
• Microsoft Excel is a table editor. Supports all functions for creating tables of any complexity.
• Microsoft Outlook is a personal communicator. It includes a task scheduler, an e-mail manager, a calendar, and an address book.
• Microsoft PowerPoint - a program for preparing presentations.
• Windows Access - database management application.
• Microsoft Communicator (Microsoft Lync) - designed for organizing communication between people by means of voice, video conversations, and text messages.
• Microsoft Publisher - an application for producing a variety of publications. The application contains tools to help you create, customize and use marketing materials.
• Microsoft Visio - An application for working with business diagrams and technical charts.
• Microsoft Project is an application for project management.
• Microsoft Query - application for viewing and selecting information from databases.
• Microsoft OneNote is an application for recording and managing notes.
• Microsoft SharePoint Designer is an application for building applications on the Microsoft SharePoint platform.
• Microsoft Picture Manager is an application for working with images.
• Microsoft Document Image Writer is a virtual printer that prints Microsoft Document Imaging Format.
• Microsoft Diagnostics - diagnostics and recovery of damaged Microsoft Office applications.

Antivirus software

This is a program designed to recognize and fight computer viruses and malicious unwanted programs. In their work, these programs use different principles to find and cure infected files. For the normal operation of a PC, every user should keep an antivirus program updated as the developers of the virus programs are constantly improving them. Users can install antivirus software as part of the software or as a stand-alone application

If the antivirus program detects a virus in the file, it deletes the program code of the virus from it. If treatment is not possible, the infected file is completely deleted.

Device drivers

A driver is a program by which the operating system understands which devices are connected to your computer and how best to communicate with them. Drivers are developed by the manufacturers of these devices (graphics card, network card, sound card, printer, etc.).

For example, you may have purchased an input device, connected it to your computer, and see that the computer does not recognize it. When you install the necessary drivers for the device, the computer will understand what the device is, what it does, and how to use it. The drivers are installed from the disk that comes with the device, or from the official website of the device manufacturer. Or, for example, you bought a sound card, installed it, and noticed that you didn't experience a difference in the sound. In this case, too, you need to install the drivers for that sound card for the device to work properly.

Drivers need to be updated regularly for your computer devices to work properly.

Basic Programs

These are programs that are integrated into the operating system. That is, they do not need to be installed, they are already in your computer from the first time it is started.

Notepad

This is a simple text editor. You can use it to enter text, edit it, and save it on your computer. All text files created by Notepad have the ".txt" extension. If you change the font or character size - it changes in the whole file. You cannot change the style of individual characters.  Documents created in Notepad take up very little space on your computer.

If you put the code sequence ".LOG" in the topmost line of the program and save it, the current date and time are added to the file after opening it.

This program is mainly used as a day planner. More advanced users can write special commands into the notepad and use it to make a simple web page, or write simple programs.

Calculator

The calculator is designed to perform computational operations. Its interface imitates the appearance of a real calculator. Its buttons are pressed with the mouse, and numeric input is possible with the keyboard.

You can paste already prepared mathematical expressions into it and get the final result. For example, if you type "2*2=" in notepad, copy and paste it with "Ctrl+V" key combination into the calculator window, you will see the number 4 in the calculator window.

Operation modes

The calculator has several operation modes: normal, engineering, graphing, programmer, and date calculation. Also, the calculator is capable of converting currencies, volume, length, weight and mass, temperature, energy, area, speed, time, power, data, pressure and angle.

Paint

This is a multifunctional graphics editor. It is designed to create and edit drawings of different colors and designs.

You can use it to delete, paint over, or blur any unwanted parts of an image.

Tools

• Tool for freehand drawing of lines.
• A tool for drawing lines in the form of a pen.
• Creates a spot of pixels in the workspace.
• Deletes elements of the image, leaving the background color.
• Creation of standard shapes in the form of a rectangle, a rounded rectangle, a polygon, an ellipse.
• Fill fills areas outlined by curved lines with color.
• Allows you to select a color from the drawing. If you put the cursor on the desired color and press the left mouse button, the color you choose becomes the main color, and if you press the right mouse button, it becomes the background color.
• Allows you to select any required fragment of the area with the left mouse button pressed. You can do any manipulations with the selected area (move, paste into drawing or remove to clipboard, cut).

Paint 3D

This is an improved version of the graphics editor. Here you can create 3D objects in volume.  You can add three-dimensional objects to your project from the built-in library, or you can use special tools to create your own.

Windows Explorer

This program allows the user to navigate the file system of your PC and manage their folders and files. It is the main graphical shell for the user. Without this program the user would not be able to fully use the operating system.

Windows Explorer includes the following tools:

• Desktop icons and the desktop itself
• Taskbar

In the latest versions of Windows, the Start menu is used separately from Windows Explorer. If for some reason Windows Explorer hangs up, the Start menu works independently of it. This is implemented in Windows 7 and higher.

Capabilities

• Create, open, copy, delete, rename files and folders.
• Manage connected disks, flash drives, and local storages.

Recycle bin

This is an element of the graphical user interface. It is designed to delete and temporarily store deleted objects. If you right-click on the recycle bin and select "Clear Recycle Bin" - all files in the recycle bin are irretrievably deleted.

1 – Empty recycle bin

2 – Recycle bin with files

macOS

It is the operating system developed at Apple Inc. macOS operating systems are the second most common operating system after Windows. They represent about 5% of the world's active computers.

This operating system is close to Linux because the macOS kernel is based on the Unix kernel, the predecessor of Linux.

This operating system is primarily oriented towards work. A large number of handy programs and applications for work and a small number of available games prove this point.

Advantages

• Fast performance and high optimization. Apple is not only a software developer, but also a creator of system units, monoblocks, and portable computers. The company's engineers strive for the best performance of the devices.
• Convenient streamlined application management, simple user interface.

• There are few malware (viruses) if you purchase apps only from official developers. The App Store will not release a malicious application, but having an anti-virus will not be out of place.
• Useful built-in programs. macOS already includes a full-featured office for work, including a word processor, spreadsheet and presentation editor, and an app for video, graphics, and audio.
• Excellent interaction between the devices of Apple products. The iPhone smartphone, iPad tablet, and Apple Watch are the best when they interact with iMac. For example, a user can start solving a task on an iOS device (iPhone, iPad) and continue to solve it with a program installed on the iMac. This includes synchronizing information between devices or moving documents in the same cloud storage iCloud.

Disadvantages

Apple devices are shipped to the store already assembled. Important components such as the processor or RAM may be soldered to the motherboard. In case of replacement of these components, there may be problems with their recognition in the system, because the hardware identifiers of the system components are programmed in the operating system.

• A small number of entertainment applications

To run a particular game may require an emulator or installation of Windows by a second system through a special application.

Linux

Linux operating system logo

Linux is an operating system based on the concept of open-source and free software.

The Linux operating system is free to use for any purpose.

A distribution is a version of an operating system, which consists of a variety of tools and interfaces associated with the operating system kernel. There are a huge number of Linux operating system distributions, such as:

1. Ubuntu
2. Mint
3. Elementary

There are some special distributions available for supercomputers, servers, and many others.

These distributions provide an opportunity for the user to choose the most suitable operating system for him/herself. There are distributions for comfortable viewing and listening to media content, for gaming, and for simplified operating systems. The Linux kernel is used by Android and for most smart devices, including televisions or refrigerators. There are over 9,000 Linux distributions in total.

Linux is a secure and stable operating system. That is how its developers talk about it. Therefore, Linux is often used on servers and other high-risk hardware. Linux is also lighter and less resource-intensive than Windows, so users choose Linux for high computing speed. Programmers use Linux choosing a special distribution with a minimal interface design and background processes, thereby increasing computing performance.

However, if you have not used Linux before, you will have to devote a lot of time to figuring out even the simplest distributions. For example, most programs are not downloaded to the operating system through a web browser, and through a package manager, which downloads software from archives. The APP store and Play Market on smartphones follow the same pattern. Most of the programs in the package manager are available for free.

If you want to install a computer game on Linux there may be complications. You may have to run a special Windows compatibility shell to run the game. However, there are more than a thousand games for Linux on Steam.

Advantages and disadvantages

• The main feature of Linux is the almost complete absence of viruses. This is because Linux, as a home operating system, is used by a small number of users. Approximately 1% of users worldwide use Linux on their home PCs.
• Linux distributions have a wide variety and are mostly free.
• Most hardware drivers are already installed in the Linux kernel.
• The system automatically encrypts disks to protect information and files.
• Linux has compatibility issues with other devices such as printers, scanners, or routers because these devices are mostly designed to work with Windows.
• Linux does not have programs such as Photoshop, Microsoft Word, and Excel.

Microsoft Windows

An operating system is a set of programs for managing your computer.

Windows is an operating system developed by Microsoft Corporation. Windows is a paid operating system that is activated with a license key.

This operating system starts at the same time as the computer is turned on. It allows the user to work with files, use the Internet and run programs, games, music.

Basic Windows Apps and Software:

• Calculator
• Notepad
• Paint photo editor
• Edge browser for surfing the Internet
• Music and video player
• Antivirus

Windows versions:

• Home Edition. This is the version for home use with simple functionality.
• This is the version for more advanced users with improved functionality.
• Enterprise - a version for corporate organizations.

Operating system versions

• Windows 1.0 (1985)
• Windows 2.0 - 2.1 (1987-1988)
• Windows 3.0 - 3.2 (1990-1994)
• Windows NT 3.1 - 3.51 (1993-1995)
• Windows 95 — Windows 4.0 (1995)
• Windows NT 4.0 (1996)
• Windows 98 — Windows 4.1 (1998)
• Windows 2000 — Windows NT 5.0 (1999)
• Windows ME — Windows 4.9 (2000)
• Windows XP — Windows NT 5.1 - 5.2 (2001-2005)
• Windows Vista — Windows NT 6.0 (2006)
• Windows 7 — Windows NT 6.1 (2009)
• Windows 8 — Windows NT 6.2 (2012)
• Windows 8.1 — Windows NT 6.3 (2013)
• Windows 10 — Windows NT 10.0 (2015)
• Windows 11 — Windows NT 10.0 (2021)

The Windows operating system is installed on more than 90% of all computers.