Operating System: Definition and Purposes

• An operating system (OS) acts as an intermediary between a computer user and the hardware.
• The OS provides an environment for users to execute programs conveniently and efficiently.
• It's a software that manages computer hardware, ensuring correct operation and preventing user programs from interfering with system operations.

Definition

• The OS sits between application programs and the hardware, acting as an interface.
• An OS is required to run other programs on a computer.
• It coordinates hardware use among system and application programs for various users.
• The OS provides an environment for programs to perform useful work.
• It performs basic tasks like recognizing input, managing files, sending output to the display, and controlling peripherals.

Basic Purposes

• The OS controls the allocation and use of the computing system's resources.
• It provides an interface between the computer hardware and the programmer, simplifying coding, creation, and debugging of applications.

Supported Tasks

• Provides facilities to create and modify programs and data files using an editor.
• Grants access to a compiler for translating user programs from high-level to machine language.
• Offers a loader program to move compiled code to the computer's memory for execution.
• Provides routines to handle I/O programming details.

Functions

• Virtual Machine: Presents users with an equivalent machine, hiding the complexity of hardware and providing a view of named files.
• Resource Manager: Acts as a resource allocator, managing processes competing for the processor, memory, and I/O devices.

Multiplexing Techniques for Resource Management

• Time Multiplexing: Different processes are given time to utilize a resource one after the other.
• Space Multiplexing: Simultaneously allocates free spaces to as many processes as it can accommodate (does not uphold the one at a time policy).

Components

• User Command Interface
• File Manager
• Device Manager
• Memory Manager
• Processor Manager
• Network Manager

User Command Interface

• Also called the OS Shell, provides a visual tool for human-computer communication.
• The user can see if an error occurred while printing or if files were successfully copied.
• Examples include: Linux Terminal, Windows Command Prompt (cmd), PowerShell.
• The command-line user interface was the primary method of communicating with a computer from the first machines and through the 1980s.

File Manager

• A software application providing a graphical or command-line interface to manage files and directories.
• Simplifies tasks such as organizing, accessing, and manipulating files.
• Examples include: Windows Explorer (Windows), Finder (macOS), Nautilus (Linux).

Device Manager

• OS control over peripheral devices like mouse, disk drives, and monitor.
• The OS instructs device drivers to write or store files to auxiliary storage devices.
• Allows users to retrieve and install device drivers, disable or enable devices, ignore malfunctioning devices, and view device properties.

Memory Manager

• A software utility working with the OS to manage memory efficiently.
• Provides features like flushing out unused memory segments.
• Modern OSs provide memory management.
• Examples include: Cacheman, Freemem, Quarterdeck MagnaRAM, RamDisk, WinRAM.

Process Manager

• Manages multiple processes running simultaneously on the OS.
• Every software application program has one or more processes associated with them when they are running.
• Functions include: Process creation and deletion, suspension and resumption, synchronization, and communication.

Network Manager

• The process of administering and managing computer networks.
• Includes performance management, fault analysis, provisioning, and maintaining quality of service.
• A distributed system is a collection of computers/processors that do not share memory or a clock.
• Processors communicate using communication lines like fiber optics or telephone lines.
• Computers in the network are connected through a communication network.
• The network can be fully or partially connected, helping users design routing and connection strategies to overcome connection and security issues.
• Distributed systems provide access to various computing resources and shared network resources, which helps with computation speed, data availability, and reliability.