Operating Systems (OS) Introduction

• Lecture 1 introduces the topic of Operating Systems (OS).

What is an Operating System?

• An OS is a software program installed on a computer.
• An OS allows computer hardware to interface and work with installed software.
• It comprehensively administrates and synchronizes computer resources through software programs.
• Variants include UNIX, MS-DOS, SWindows, Windows/NT, and VM.
• Security is achieved using layered software safeguards.
• Clear distinctions exist within an OS: kernel services, library services, and application-level services.
• These three categories create discrete partitions.
• Applications are executed via processes interconnected by libraries.
• Libraries are collections of reusable code offering functions such as memory management, file handling, network protocols, and graphics.

Kernel's Role

• The kernel is the OS's core.
• The kernel bridges software applications and computer hardware.
• It manages system resources, including the CPU, memory, and devices.
• The kernel ensures smooth and efficient operation.
• The kernel handles tasks like running programs, accessing files, and connecting to devices like printers and keyboards.

Kernel vs OS

• Kernels are responsible for hardware interactions within a specific range, while the OS handles hardware interactions the full computer.
• Kernels trigger SystemCalls, which notify the OS of available resources.
• The OS handles these SystemCalls to utilize the resource.

OS vs Kernel: Definition, Role, Interaction, Complexity, and Components

• OS Definition: Software that manages all hardware and software resources.
• Kernel Definition: The core part of an OS that handles communication between hardware and software.
• OS Role: Provides a user interface and manages apps, security, and system resources.
• Kernel Role: Handles system-level tasks like process management, memory management, and hardware control.
• OS Interaction: Users interact with the OS through GUIs or command lines.
• Kernel Interaction: Operates in the background without direct user interaction.
• OS Complexity: A complex system with user interface, file system etc.
• Kernel Complexity: Focuses on core system processes and resource management.
• OS Components: Includes the kernel, file system, user interface, and utilities.
• Kernel Components: Manages memory, processes, and hardware.

OS vs Kernel: Resource Management, Error Handling, Security, Multi-tasking, and Communication

• OS Resource Management: Manages high-level resource allocation and distribution among various processes and applications.
• Kernel Resource Management: Performs low-level tasks like memory allocation, process scheduling, and device management.
• OS Error Handling: Errors can often be fixed without affecting the entire system.
• Kernel Error Handling: Errors can cause system crashes or halts due to its control over critical functions.
• OS Security: Provides user-level security features like password protection and access control.
• Kernel Security: Enforces security at a system level, controlling hardware access and managing permissions for applications and processes.
• OS Multi-tasking Management: Allows multiple applications and processes to run simultaneously.
• Kernel Multi-tasking Management: Task scheduling , process prioritization (multi-tasking).
• OS Communication: Handles communication between applications and system hardware.
• Kernel Communication: Ensures communication between hardware and system processes using device drivers.

Tasks of an Operating System

• Reading data from the keyboard.
• Sending data to the display screen.
• Managing files and directories.
• Taking command of peripheral equipment like printers and disk drives.

OS Architecture

• OSes support modern computer devices, from mobile phones to servers.
• OS design significantly affects performance, flexibility, and security.
• The design of each architecture impacts performance, flexibility, and security.
• Different OS architectures exist.
• The fundamental ideas and examples of operating systems that use each technique will be discussed.

Monolithic OS Architecture

• Contains a monolithic OS architecture composed of only one individual block.
• The kernel and device drivers are the main elements of the single module.
• Handles all system activities and the basis for monolithic OS design.
• The kernel is where the OS carries out its responsibilities.
• The kernel manages files, memory, devices, and processes with direct control.

Monolithic OS: Benefits

• Swift: Characterized by speed and enhanced scheduling capabilities.
• Every component and the kernel can communicate directly improving speed.

Monolithic OS: Benefits, cont.

• Uncomplicated: Components in the same address space makes development straightforward (easy to understand and use).

Monolithic OS: Cons

• Difficult to Update: Adding or removing features is difficult due to code concentration.
• Not Portable: Code is difficult to carry or transfer as they are incompatible.
• The entire code needs to be relocated for it to operate as intended.