Operating System basics

Introduction of Operating system

An Operating System (OS) is crucial software that manages computer hardware and provides services for computer programs. It serves as an intermediary between users and the computer hardware, enabling users to interact with the system and run applications efficiently. Here’s a comprehensive introduction:

1. Definition

An Operating System is a system software that manages computer hardware, software resources, and provides common services for computer programs. It acts as a bridge between users and the hardware components of a computer system.

Need of an operating System

1. Resource Management

• Hardware Abstraction: The OS abstracts the complexity of hardware by providing a simplified interface for applications and users. It handles the intricate details of hardware operations and resource management.
• Resource Allocation: Efficiently allocates hardware resources like CPU time, memory, and storage among various applications and users, ensuring that multiple processes can run simultaneously without conflicts.

2. Process Management

• Process Scheduling: Manages the execution of processes by scheduling them in a way that optimizes CPU usage and overall system performance. Implements multitasking, allowing multiple processes to run concurrently.
• Process Isolation: Ensures that processes do not interfere with each other, providing process isolation and protection.

3. Memory Management

• Memory Allocation: Manages memory allocation and deallocation for applications. Keeps track of memory usage and ensures that each process has the required memory without overlapping with other processes.
• Virtual Memory: Uses techniques like paging and segmentation to extend the available memory beyond physical RAM, allowing applications to use more memory than physically available.

4. File System Management

• File Organization: Provides a structured way to store, retrieve, and organize files on storage devices. Manages file creation, deletion, and modification.
• Access Control: Implements security measures to control file access and permissions, ensuring that only authorized users can access or modify files.

5. Device Management

• Device Drivers: Provides drivers and interfaces for hardware devices like printers, disk drives, and network adapters. Manages communication between the hardware and software.
• Input/Output Operations: Handles I/O operations, ensuring that data is correctly transferred between hardware devices and applications.

6. User Interface

• User Interaction: Provides a user interface (either graphical or command-line) that allows users to interact with the system. Makes it easier for users to run applications, manage files, and perform system operations.
• Ease of Use: Enhances the usability of the computer by providing intuitive tools and interfaces for interacting with the system.

7. Security and Protection

• Authentication and Authorization: Ensures that users are properly authenticated and authorized to access system resources. Protects the system from unauthorized access and potential security threats.
• Data Protection: Implements measures to protect data from corruption, loss, or unauthorized access. Includes features like encryption and backup.

8. Networking

• Network Management: Facilitates communication between computers over a network. Manages network connections, protocols, and data transfer, enabling features like file sharing and remote access.
• Resource Sharing: Allows sharing of resources such as printers and files across a network, improving efficiency and collaboration.

9. System Performance

• Optimization: Continuously optimizes system performance by managing resources, handling processes, and minimizing conflicts. Provides tools and utilities to monitor and improve system performance.
• Error Handling: Detects and handles errors and exceptions, providing stability and reliability to the system.

Conclusion

An Operating System is essential for providing a stable, efficient, and secure computing environment. It enables users to interact with hardware and software, manages resources, ensures security, and optimizes performance, making it a fundamental component of any computer system

Functions of an Operating System

• Process Management: Manages processes in a system, including their creation, scheduling, and termination. Ensures that processes are executed efficiently and manages the execution of multiple processes simultaneously (multitasking).
• Memory Management: Handles allocation and deallocation of memory space. Keeps track of each byte in a computer’s memory and ensures that each process and application gets the necessary memory.
• File System Management: Manages files on storage devices. Provides a way to store, retrieve, and organize files, and manages permissions and access controls for files and directories.
• Device Management: Controls and coordinates the use of hardware devices such as printers, disk drives, and network interfaces. Provides drivers and handles input/output operations.
• User Interface: Provides a user interface (UI) that allows users to interact with the computer. This can be graphical (GUI) or command-line based.
• Security and Access Control: Protects the system from unauthorized access and ensures that users have appropriate permissions to access resources. Handles authentication, authorization, and auditing.
• Networking: Manages networking functions, including communication between computers over a network, handling network connections, and ensuring data transfer.

Various Operating system used presently

As of now, various operating systems are used across different types of devices, including personal computers, servers, mobile devices, and embedded systems. Here’s a summary of the major operating systems currently in use:

1. Personal Computer Operating Systems

• Microsoft Windows:
  • Windows 10: Widely used in personal computers and laptops; known for its user-friendly interface and extensive application support.
  • Windows 11: The latest version, offering a redesigned interface, improved performance, and new features.
• macOS:
  • macOS Ventura: The latest release for Apple Mac computers, known for its integration with Apple’s ecosystem, user-friendly interface, and security features.
  • macOS Monterey: Previous version with a focus on productivity and enhanced features.
• Linux Distributions:
  • Ubuntu: A popular user-friendly distribution known for its ease of use and community support. Often used in personal computing and as a server OS.
  • Fedora: Known for incorporating cutting-edge technologies and its strong focus on open-source development.
  • Debian: A stable and versatile distribution that serves as the foundation for many other distributions, including Ubuntu.
  • Arch Linux: Known for its minimalism and flexibility, allowing users to customize their systems extensively.

2. Mobile Operating Systems

• Android:
  • Android 14: The latest version of Google’s open-source mobile OS, widely used in smartphones and tablets with a large number of applications available through the Google Play Store.
• iOS:
  • iOS 17: The latest version for Apple’s iPhone and iPad, known for its smooth integration with Apple’s ecosystem and security features.

3. Server Operating Systems

• Windows Server:
  • Windows Server 2022: The latest version providing enhanced security, performance, and integration with cloud services.
• Linux Server Distributions:
  • Red Hat Enterprise Linux (RHEL): A commercial distribution known for its stability and enterprise-level support.
  • CentOS: Previously a community-driven distribution closely aligned with RHEL, now succeeded by CentOS Stream.
  • SUSE Linux Enterprise Server (SLES): Known for its enterprise support and reliability.

4. Real-Time Operating Systems (RTOS)

• VxWorks: A widely used RTOS in embedded systems for aerospace, automotive, and industrial applications.
• QNX: Known for its use in automotive systems, medical devices, and other embedded applications requiring real-time performance.
• FreeRTOS: An open-source RTOS widely used in embedded systems for microcontrollers.

5. Embedded Operating Systems

• Android Things: A version of Android tailored for IoT and embedded devices.
• Windows IoT: A version of Windows designed for Internet of Things devices and embedded systems.

6. Specialized and Legacy Operating Systems

• Unix: A family of multitasking, multiuser operating systems derived from the original AT&T Unix. Includes commercial versions like AIX (IBM), HP-UX (Hewlett Packard), and Solaris (Oracle).
• IBM z/OS: Mainframe operating system used on IBM’s zSeries mainframes, known for its reliability and performance.

These operating systems cater to various needs and types of devices, from personal computing and mobile devices to servers and embedded systems. Each OS has its own features, advantages, and target use cases, providing flexibility and functionality to meet diverse user requirements.

Classify DOS Commands

DOS stands for Disk Operating System. It is a family of operating systems that were widely used in the early days of personal computing, primarily for managing files and running applications from a command-line interface. Here’s a detailed overview of DOS:

1. Definition

DOS is an operating system designed to manage disk storage, control hardware, and provide a platform for running application software. It primarily uses a command-line interface (CLI), where users type commands to perform operations.

List 10 Internal commands

1. DIR

• Description: Lists the files and directories in the current or specified directory.
• Usage:

DIR [drive:][path][filename] [/options]

drive:: Specifies the drive to list (e.g., C:).
path: Specifies the directory path.
filename: Specifies the file(s) to list (e.g., *.txt for all text files).
/options: Includes additional options like /W (wide listing), /P (pause after each screen), /S (list files in subdirectories), etc.

2. CD (Change Directory)

• Description: Changes the current working directory.
• Usage:

CD [directory]

directory: Specifies the path to the new directory. Use .. to move up one level
Example:

CD C:\Program Files

Changes the current directory to C:\Program Files

3. MD or MKDIR (Make Directory)

• Description: Creates a new directory.
• Usage:

MD [directory]

directory: Specifies the name of the new directory to create.
Example:

MD C:\NewFolder
Creates a new directory named NewFolder in C:\.

4. RD or RMDIR (Remove Directory)

• Description: Removes a directory. The directory must be empty to be removed.
• Usage:

RD [directory]

directory: Specifies the name of the directory to remove.
Example:

RD C:\OldFolder
Removes the OldFolder directory from C:\, provided it is empty.

5. COPY

• Description: Copies files from one location to another.
• Usage:

COPY [source] [destination] [/options]

• source: Specifies the file(s) to copy.
• destination: Specifies the location to copy the file(s) to.
• /options: Includes options like /Y (suppress confirmation prompt), /V (verify the new file).
  example:

COPY C:\file.txt D:\Backup\
Copies file.txt from C:\ to D:\Backup\.

6. DEL or ERASE

• Description: Deletes one or more files.
• Usage:

DEL [file(s)] [/options]

file(s): Specifies the file(s) to delete (use *.txt for all text files).
/options: Includes options like /P (prompt before deleting), /Q (quiet mode, no prompts).
Example:

DEL C:\file.txt
Deletes file.txt from C:\.

Command	Syntax	Description
CD	CD [drive:][path]Change	ges the current directory to the specified folder.
DIR	DIR [drive:][path]	Displays a list of files and subdirectories in a directory.
COPY	COPY [destination]	Copies files from one location to another.
DEL	DEL [drive:][path]	Deletes one or more files.
REN	REN [drive:][path][filename1] [filename2]	Renames a file or directory.
MKDIR	MKDIR [drive:][path]	Creates a new directory.
RMDIR	RMDIR [drive:][path]	Removes an existing directory.
TYPE	TYPE [drive:][path]	filename Displays the contents of a text file.
EDIT	EDIT [drive:][path]filename	Opens the MS-DOS text editor for editing a specified file.
CHKDSK	CHKDSK [volume:][[path]filename] [/F] [/V] [/R] [/X] [/I] [/C] [/L[:size]] [/B]	Scans and fixes errors on a disk.
FORMAT	FORMAT volume [/FS:file-system] [/V:label] [/Q] [/L[:size]] [/A:size] [/C] [/X]	Prepares a storage medium for data storage.
XCOPY	XCOPY [destination] [/E] [/C] [/H] [/R] [/Y]	Copies files and directories, including subdirectories.
TREE	TREE [drive:][path]	Graphically displays the folder structure of a drive or path.
DATE	DATE [MM-DD-YYYY]	Displays or sets the system date.
TIME	TIME [HH: MM: SS]	Displays or sets the system time.
HELP	HELP [command]	Provides help information for MS-DOS commands.
EXIT	EXIT	Exits the MS-DOS command prompt or a batch file.
ATTRIB	ATTRIB [+ R|-R] [+A|-A] [+ H|-H] [+ S|-S] [d:][path]filename [/S]	Sets or clears file attributes (Read-Only, Archive, System, Hidden), managing file visibility and access in MS-DOS.
MODE	MODE [device] [BAUD=b] [PARITY=p] [DATA=d] [STOP=s]	Configures system devices.
DISKCOPY	DISKCOPY [drive1:][path1][filename1] [drive2:][path2][filename2]	Copies the contents of one disk to another.
MEM	MEM[/program|/debug|/classify|/free|/module(name)] [/page]	Displays the amount of used and free memory in the system.
SCANDISK	SCANDISK [/SURFACE] [/AUTOFIX] [/CHECKONLY]	Scans and fixes disk errors.
UNDELETE	UNDELETE [drive:][path][filename]	Restores a deleted file.
ASSIGN	ASSIGN [drive1:=[drive2:]]	Redirects requests for drive letters to a different drive.
FDISK	FDISK	Manages disk partitions.
BACKUP	BACKUP [destination] [/S]	Backs up files and directories.
RESTORE	RESTORE [destination] [/S]	Restores files and directories from a backup.
MSCDEX	MSCDEX [/D: driver /L:drive] [/M:bufsize] [/E /S /V]	Provides CD-ROM access.
SYS	SYS [drive1:][path]	Transfers system files to a disk.
SHARE	SHARE [/F:(space)] [/L:(locks)]	Installs file-sharing and locking capabilities.
SMARTDRV	SMARTDRV [size] [/E /V] [/C] [/L:size]	Disk caching utility.
SETVER	SETVER [drive:][path]filename [/B:bytes]	Sets the MS-DOS version number for a program.
ASSIGN	ASSIGN [/D]	Disables automatic drive-letter assignments.
FASTHELP	FASTHELP [command] [command] /?	Provides a quick overview of MS-DOS commands.
FC	FC [/A] [/C] [/L] [/LBn] [/N] [/OFF[LINE]] [/T]	Compares two files or sets of files and displays the differences between them.
FIND	FIND [/V] [/C] [/N] [/I] [/OFF[LINE]] “string” [[drive:][path]filename[ …]]	Searches for a text string in files.
MORE	MORE [filename]	Display the content of a text file one screen at a time
ECHO	ECHO [on/off]	This command can either show or hide the text of the commands you type. Command echoing is on by default
ECHO	ECHO [<message>]	Specifies the text to display on the screen.
PATH	PATH [[drive:][path] [;…]]	Displays or sets a search path for executable files.
SET	SET [variable=[string]]	Sets or displays environment variables.

DOS External Commands

2. External commands: –  This commands are not permanent part of the memory. To execute or run this commands an external file is required.

Example : [.] Dot  exe, bat.

Some commonly used DOS external commands are .

1. CHKDSK:- The command CHSDK returns the configuration status of the selected disk. It returns the information about the volume, serial number, total disk space, space in directories, space in each allocation unit, total memory and free memory.

Syntax : – C : / > CHKDSK drive name

Eg:- C : / > CHKDSK   e :

If drive name is not mentioned by default current drive is considered.

2. Diskcopy : – Disk copy command is used to make duplicate copy of the disk like Xerox copy. It first formats the target disk and then copies the files by collection. From the source disk and copied to the target disk.

Syntax : – C : / > disk copy < source path > < destination path >

Ex: – c : / > diskcopy A : B :

NOTE: – This command is used after diskcopy command to ensure that disk is copied successfully.

3. Format : – Format is used to erase information off of a computer diskette or fixed drive.

Syntax : – C : / > format drive name

Ex : C : / > format  A:

4. Label : This command is used to see volume label and to change volume label.

Syntax : C : / > label drive name

Ex : C : / > label  A:

5.Scandisk : – This utility is used to repair and check various  disk errors. It also defects various physical disk errors and surface errors.

Syntax : – C : / > scandisk < drive names >

 C : / > Scandisk  A :

6. Move : The purpose of move is move to files from one place to another place.

Syntax: C : / > Move < source path > < target  path >

7. Print :This command allowed users to print a text file to a line printer.

Syntax : C : / > Print  < files name >

C : / > print ramu

8. Tree : This command displays the list of directories and files on specified path using graphical display. It displays directories of files like a tree.

Syntax:- C : / > tree > path

C : / > tree  A:

9. Deltree: This command is used to delete files a directories same as by the del and RD commands. This command is more useful than del and RD commands because it completely removes specified directories ie.,  disk will all it files and sub – directories at a time.

Syntax:- C : /  > deltree (path)

C : / > deltree  A:/>ramu 

Features of Windows Desktop

The Windows Desktop environment provides a comprehensive user interface and a set of features designed to facilitate user interaction with the operating system and applications. Here’s a detailed look at the key features of the Windows Desktop:

1. Graphical User Interface (GUI)

• Desktop Background: The area of the screen where icons, widgets, and windows appear. Users can customize the background image or color.
• Taskbar: A bar typically located at the bottom of the screen, which displays open applications, system notifications, and the Start Menu.
• Start Menu: Provides access to applications, system settings, and power options. It includes pinned apps, a list of installed programs, and a search bar.

2. Window Management

• Windowed Applications: Applications run in resizable and movable windows. Users can minimize, maximize, or close windows using buttons in the top-right corner.
• Snap Assist: Allows users to easily snap windows to the edges of the screen for side-by-side viewing or to maximize them.

3. File and Folder Management

• File Explorer: A tool for navigating and managing files and folders. It provides views like icons, list, and details, and supports drag-and-drop functionality.
• Context Menus: Right-click menus that provide quick access to common file operations such as copy, paste, delete, and properties.

4. System Tray and Notifications

• System Tray: Located on the right side of the taskbar, it shows system icons and notifications for background applications and services.
• Notifications: Alerts from applications and system events, which can be accessed by clicking the notification icon in the system tray.

5. Search Functionality

• Search Box: Located on the taskbar or Start Menu, it allows users to quickly search for files, applications, settings, and web results.
• Cortana: Microsoft’s virtual assistant (in certain versions) that helps with searches, reminders, and other tasks.

6. User Accounts and Personalization

• User Accounts: Allows multiple users to have their own settings, files, and preferences. Supports account types such as Administrator and Standard User.
• Personalization Options: Customization settings for desktop backgrounds, themes, screen savers, and color schemes.

Benefits of Windows

Windows, as an operating system, offers a wide range of benefits that contribute to its widespread use in both personal and professional environments. Here are some of the key benefits:

1. User-Friendly Interface

• Graphical User Interface (GUI): Windows provides a visually intuitive interface with icons, windows, and menus, making it accessible even for users with minimal technical expertise.
• Start Menu: Offers easy access to applications, settings, and system functions, enhancing usability and navigation.

2. Extensive Software Compatibility

• Wide Range of Applications: Windows supports a vast array of software applications for productivity, entertainment, and professional use, including popular programs like Microsoft Office, Adobe Creative Suite, and various games.
• Legacy Software Support: Windows maintains compatibility with older software, allowing users to run legacy applications without significant issues.

3. Strong Hardware Compatibility

• Broad Device Support: Windows is compatible with a wide range of hardware, including desktops, laptops, tablets, and peripherals. This extensive compatibility is due to drivers provided by hardware manufacturers and Microsoft.

4. Integration with Microsoft Ecosystem

• Microsoft Office Suite: Seamless integration with Microsoft Office applications, such as Word, Excel, and PowerPoint, which are widely used in business and education.
• OneDrive: Built-in cloud storage service that allows for easy file synchronization and access across multiple devices.

5. Regular Updates and Support

• Security Updates: Regular updates to address security vulnerabilities and enhance system stability. This includes patches and improvements to protect against malware and other threats.
• Technical Support: Access to customer support and extensive online resources for troubleshooting and assistance.