Operating System

2.1. Introduction to Operating System

An Operating System (OS) is system software that, after being loaded onto the computer by a boot program, manages a computer's hardware, provides services for computer programs, and acts as an intermediary between users and the computer hardware.

Key Roles of an Operating System:

Processor Management: Scheduling tasks and managing processor cycles.
Memory Management: Overseeing the physical and virtual memory in the system.
Device Management: Acting as a bridge to transmit generalized input/output instruction translations to device drivers.
Storage Management: Directing permanent storage, such as reading/writing data to disks.
Security and Access Control: Protecting against unauthorized access, viruses, and ensuring data integrity.
User Interface Provision: Providing interfaces for user interaction, including graphical user interfaces (GUIs) and command-line interfaces (CLI).

2.2. Types of Operating System

Batch Operating System: Processes batches or groups of jobs without manual intervention.
Multiprogramming Operating System: Multiple programs run concurrently, maximizing processor utilization by multitasking.
Multitasking Operating System: Multiple tasks or processes run on a single OS, with the user rapidly switching between them, giving the illusion they're running simultaneously.
Real-Time Operating System (RTOS): Designed for real-time applications that require immediate responses, like embedded systems, medical imaging, and industrial systems.
Multi-user Operating System: Allows multiple users to access a computer system at the same time, typically used in networked environments.
Distributed Operating System: Distributes the workload among multiple computers. Each individual computer has a subset of the OS working in conjunction.
Embedded Operating System: Optimized to run on embedded computer systems, like appliances, cars, and industrial robots.

Popular Operating Systems in Modern Use:

Windows: Developed by Microsoft, Windows has a series of graphical interface-based OSs.
MacOS: Apple's operating system for its series of Macintosh computers.
Linux: An open-source operating system, it's used in various distributions like Ubuntu, Fedora, and Debian.
Unix: Developed in the late 1960s, various forms of Unix have been influential in the development of other OSs.
Android: Based on the Linux kernel, it's primarily used on mobile devices.
iOS: Apple's mobile operating system for iPhones and iPads.

2.3. Functions of Operating Systems

The Operating System (OS) plays a crucial role in the management and coordination of activities and sharing of the resources of a computer. Here are its main functions:

Process Management:
- Scheduling: Determines which process runs, when, and for how long.
- Multitasking: Allows multiple processes to run concurrently.
- Process Synchronization and Coordination: Ensures processes operate correctly in relation.
Memory Management:
- RAM Management: Allocates and deallocates RAM for processes.
- Virtual Memory Management: Uses disk space as an extension of RAM.
File System Management:
- File Operations: Includes creating, deleting, reading, and writing files.
- Directory Operations: Includes creating, deleting, and naming directories.
- Backup and Restore: Protects against data loss.
Device Management:
- Drivers: Interfaces between the computer and peripheral devices.
- I/O Management: Coordinates input and output operations.
Security and Access Control:
- Authentication: Verifies user identity.
- Authorization: Grants or denies access to specific resources based on user identity.
- Encryption: Protects information from unauthorized access or tampering.
User Interface Provision:
- Command-Line Interface (CLI): Text-based user interface for command input.
- Graphical User Interface (GUI): Visual-based interface using windows, icons, and interactive visuals.
Networking: Manages connections, communications, and data exchanges between systems in a network.
System Performance Monitoring: Monitors system activities and resources, helping ensure efficiency and performance.

2.4. Command Line Operation

The Command-Line Interface (CLI) allows users to perform tasks by typing commands rather than using a graphical interface. Here are some basic command line operations, primarily based on UNIX-like systems and Windows:

Copy Command:
- UNIX/Linux: cp [source] [destination]
- Windows: copy [source] [destination]
Move Command:
- UNIX/Linux: mv [source] [destination]
- Windows: move [source] [destination]
View File Attributes:
- UNIX/Linux: ls -l [file/directory name] (also shows file permissions)
- Windows: attrib [file/directory name]
Set File Attributes:
- UNIX/Linux: To change file permissions, use chmod [permissions] [file/directory name]. Permissions can be represented numerically or symbolically.
- Windows: To set attributes like "read-only", use attrib +R [file/directory name] (and R to remove).
Delete Command:
- UNIX/Linux: rm [file name]
- Windows: del [file name]
Directory Operations:
- Create: UNIX/Linux uses mkdir [directory name] and Windows uses mkdir [directory name] or md [directory name].
- Change Directory: Both UNIX/Linux and Windows use cd [directory path].
- List Directory Contents: UNIX/Linux uses ls and Windows uses dir.

2.5. Windows

2.5.1. Introduction to GUI (Graphical User Interface)

Graphical User Interface (GUI) is a type of user interface that allows users to interact with devices through graphical icons and visual indicators, rather than textual commands or a command-line interface.

Characteristics of GUI:

Icons: Represent different files, applications, and functions.
Windows: Allows multiple programs or views to be open and visible at the same time.
Menus: List of options users can choose from.
Pointers: Cursors are used to navigate and select items, usually controlled by a mouse or touchpad.
Buttons: Clickable elements to initiate actions.
Ease of Use: Intuitive and user-friendly, often requiring little to no technical expertise.

The shift from command-line interfaces to GUIs revolutionized personal computing, making computers accessible to a broader audience.

2.5.2. Introduction of Windows Operating System

Windows is a series of operating systems developed by Microsoft, one of the best-known software brands worldwide. It provides an environment where users can run applications, browse the internet, manage files, and perform many other computing tasks.

Brief History & Versions:

Windows 1.0 (1985): The original version, introducing GUI concepts to PC users.
Windows 3.1 (1992): Brought advancements in stability and introduced the Program Manager.
Windows 95: Major overhaul of the OS, introduced the Start menu and taskbar.
Windows XP (2001): One of the most popular versions, known for its improved stability and usability.
Windows Vista (2007): A visually enriched OS but faced criticism for heavy resource requirements.
Windows 7 (2009): Addressed many Vista criticisms, became a widely adopted OS.
Windows 8 (2012): Introduced a significant change with the Metro UI, targeting touch devices. It was met with mixed reviews.
Windows 10 (2015): Current major version (as of the last update in 2021), blending the traditional desktop and Metro UI. Introduced features like the Edge browser and Cortana voice assistant.

Notable Features of Windows OS:

User-friendly Interface: Easily navigable GUI with icons, windows, and menus.
Multitasking: Supports running multiple applications simultaneously.
Wide Software Compatibility: Supports a vast range of applications and software.
Security: Comes with built-in security features like Windows Defender.
Regular Updates: Microsoft frequently releases updates, adding new features and addressing security concerns.

2.5.2.1. Basic Windows Elements

Desktop: The main screen or workspace in the Windows environment. It can contain icons, files, applications, and folders.
Taskbar: A bar usually at the bottom of the desktop, which displays open applications, the Start menu, system tray (with notifications, clock, etc.), and quick access icons.
Start Menu: Accessed by clicking on the Windows logo in the taskbar, it provides shortcuts to programs, system settings, and other important features.
My Computer (later renamed to "Computer" or "This PC"): Provides access to drives (both local and external), as well as system folders and network locations.
Recycle Bin: A temporary storage for files that have been deleted. Files can be restored from the Recycle Bin or permanently deleted from it.
Windows Explorer: The main tool for navigating through files and folders on your computer.

2.5.2.2. Starting and Shutting Down Windows

Starting Windows: Normally, turning on your computer will automatically boot up Windows, unless you have multiple operating systems installed.
Shutting Down Windows: Click on the Start menu, find the power icon, and select "Shut Down" from the options. There are also options for restarting or putting the computer to sleep.

2.5.2.3. File Management with Windows Explorer

Navigation Pane: On the left side, it provides quick access to frequent folders and locations.
Main Pane: Displays the contents of the current location or folder.
Breadcrumb Navigation: Shows the path to the current location, allowing quick navigation to parent folders.
Creating a New Folder: Right-click within the main pane -> New -> Folder.
Copying/Moving Files: Drag files to new locations or right-click -> Copy/Cut, then Paste in the desired location.
Search Bar: Allows users to quickly search for files or folders.

2.5.2.4. Windows Applications

Control Panel: Central place for system settings, where you can modify system and hardware settings.
Character Map: A utility to view characters in a selected font, especially helpful for finding special or non-standard characters.
Paint: A simple graphic software to create or edit images.
Notepad: A basic text editor for creating and editing plain text files.
Calculator: Provides basic to advanced mathematical calculations.
WordPad: A basic word processor that's more advanced than Notepad but less feature-rich than Microsoft Word.

2.5.2.5. Finding Files or Folders and Saving the Result

Searching in Windows Explorer:
- Use the search bar in the top-right corner of Windows Explorer.
- Start typing the name of the file or folder you're looking for, and the results will appear dynamically.
- You can save searches in certain versions of Windows by clicking "Save Search" after performing it.

2.5.2.6. Starting a Program by Command Line Operation

Using the Command Prompt or Windows PowerShell:
- Open Command Prompt or Windows PowerShell from the Start menu or by pressing Win + R and typing cmd or powershell.
- Input the path of the program's executable or simply its name if it's in the system path. For example, typing notepad and pressing Enter will launch Notepad.

2.5.2.7. Changing Window Settings

Windows offers a plethora of settings that users can adjust to customize their experience.

Accessing Settings:
- Click on the Start menu and select Settings (a gear-shaped icon) to access the primary settings app in Windows 10.
- For older versions or a broader range of options, the Control Panel is available.
Personalization:
- Customize the desktop background, colors, lock screen, themes, and more.
Display Settings:
- Adjust screen resolution, orientation, brightness, and other display-related settings.
Privacy Settings:
- Manage which apps and system features can access user data and hardware like the camera or microphone.

2.5.2.7.1. Adding/Removing Programs

Using Settings in Windows 10:
- Go to Settings > Apps > Apps & features. Here, you can see a list of installed applications.
- Click on an app to reveal options to Modify or Uninstall it.
Using Control Panel in Older Versions or for Advanced Options:
- Open the Control Panel and select Programs or directly Programs and Features.
- This will provide a list of currently installed software. By selecting a program, you can choose to Change or Uninstall it.

2.5.2.7.4. Control Panel Items

The Control Panel in Windows offers a collection of applets to configure different aspects of the system. Some common items include:

System: Displays information about the computer and allows changes to performance and hardware settings.
Devices and Printers: Manages connected devices like printers, scanners, and other peripherals.
Network and Sharing Center: Configure network settings and view network status.
Programs and Features: Allows users to uninstall, change, or repair software installed on the PC.
Security and Maintenance: Provides access to security and maintenance-related features.
Date and Time: Allows setting of time zones, date, and time formats.
Ease of Access Center: Offers tools and settings to improve computer accessibility.
User Accounts: Manage user accounts, passwords, and related settings.

2.5.2.8. Creating Shortcuts (Icons) on Desktop

To create a shortcut on the desktop:

Right-click on an empty space on the desktop.
Hover over New, and then click on Shortcut from the dropdown menu.
Browse to the item or program you want to create a shortcut for or type in its path.
Click Next, name your shortcut, and then click Finish.

You can also create shortcuts by right-clicking on an application or file, selecting Send to, and then choosing Desktop (create shortcut).

2.5.2.9. Systems Tools

Several system tools in Windows assist in maintaining the health and performance of the system:

Disk Scanning (Check Disk): Scans the disk for logical and physical errors. It can be run by typing chkdsk in the Command Prompt.
Disk Defragmenter: Over time, files on a hard drive can become fragmented, meaning parts of files are spread out across the disk. The Disk Defragmenter rearranges these fragments to improve read/write performance. Accessible via: Control Panel > Administrative Tools > Defragment and Optimize Drives.
Backup: Windows includes a backup utility that allows users to create copies of files or create a system image. In Windows 10, this is found under Settings > Update & Security > Backup.
Restore: System Restore allows the computer to revert to a previous state, using "restore points" that have been saved over time. Useful when facing system malfunctions after installing new software or drivers.
Format: This tool prepares a disk for use, erasing all data and setting up a file system. To format a drive, you can right-click on it in File Explorer and select Format.

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