Operating Systems Overview

Operating Systems

• Definition: Software that manages computer hardware and software resources, connecting users to computers
• Types: Batch, time-sharing, distributed, real-time, and embedded systems

Core Components

• Kernel: The core of the OS, managing system resources and communication between hardware and software
• Shell: A user interface enabling interaction with the OS, often through command lines
• Utilities: Tools for specific tasks to support user operations and system management

Random Access Memory (RAM)

• Definition: Volatile memory, storing actively used or processed data for rapid access
• Memory Addressing: Memory locations are identified by unique addresses (e.g., hexadecimal)
• Address Register: Stores the address of the accessed memory location

Process Management

• Process: A program in execution, utilizing memory space and resources.
• Job, Thread, Task: Units of work scheduled for execution by the OS. Threads are smaller execution units within a process and can be managed independently.
• Scheduling Algorithms: Techniques for process execution; examples include First Come First Serve (FCFS).

Memory Management

• Techniques: Manage memory allocation, including paging and segmentation, for efficient data storage & retrieval
• Virtual Memory: Allows process execution even without being fully loaded, enhancing multitasking.

Performance Metrics

• CPU Utilization: Keeping the CPU busy as possible
• Throughput: The number of processes completed within a given time
• Turnaround Time: Total execution time of a process
• Response Time: Time from the initial request to the first response

Security and Permissions

• Mechanisms: Protect against unauthorized access and ensure secure OS operations.

Distributed Systems

• Overview: Management of resources across multiple interconnected systems, emphasizing communication and coordination.

Networking Models

• OSI Model: Seven-layer framework for understanding network communication
• TCP/IP Model: Four-layer model (Application, Transport, Internet, and Network Access) crucial for grasping data flow

Routers

• Device connecting 2+ networks, managing traffic between them
• Routing Table: Tracks paths for routing data packets to destinations

Low-Layer Protocols

• Ethernet and Wi-Fi: Responsible for data transmission over physical mediums, including framing, error detection & addressing. Includes IEEE 802.3 (Ethernet) and IEEE 802.11 (Wi-Fi).

Address Resolution Protocol (ARP)

• Maps IP addresses to MAC addresses, enabling communication between devices on a local network.

Domain Name System (DNS)

• Translates human-readable domain names (like sdu.dk) into IP addresses

HyperText Transfer Protocol (HTTP)

• Client-server protocol for transferring web pages, using GET and POST methods for client requests.

Multicast

• Efficient communication method where data from one sender is sent simultaneously to multiple specific recipients.

Routing Protocols

• RIP (Routing Information Protocol) and OSPF (Open Shortest Path First): Essential for determining the best data transmission paths across networks

Autonomous Systems (AS)

• Large networks or groups of networks under a single administrative control, managing IP addresses and routing policies; crucial for managing internet traffic

Distributed Systems Concepts

• Fault Tolerance: System's ability to operate properly when components fail.
• Data Consistency: Ensuring all nodes have the same data simultaneously.
• Scalability: Ability to handle increasing workloads.

Protocols for Delivering Audio and Video Using IP

• Web Real-Time Communication (WebRTC) framework, used for audio, video, and data transfers between browsers
• Real-time Transport Protocol (RTP): Delivers audio/video over IP networks.
• RTP Control Protocol (RTCP): Provides feedback on media quality in real-time communication
• Session Traversal Utilities for NAT (STUN): Allows clients to discover their public IP address.
• Traversal Using Relays around NAT (TURN): Used when direct peer-to-peer communication isn't possible, relaying media through a server

Protocols for Video Streaming

• HTTP Live Streaming (HLS): For streaming media over the internet, developed by Apple.
• Dynamic Adaptive Streaming over HTTP (DASH): Adaptive bitrate streaming protocol allowing for high-quality streaming.
• Real-time Messaging Protocol (RTMP): For streaming audio, video, and data using the internet.

Data Processing Methodologies

• Batch Processing: Processing large data blocks simultaneously, efficient for historical data but has notable latency
• Stream Processing: Processing continuous data in real time, ensuring timely delivery but lacking error correction

Apache Kafka

• A platform for real-time data pipelines and event streaming
• Provides high throughput and fault tolerance.

Kubernetes

• Container orchestration platform
• Automates deployment, scaling and management of containerized applications
• Offers a framework for microservices and distributed systems.

File Systems

• Types of File Systems (NTFS, FAT32, EXT4, APFS) and their use Cases
• Data Management: Inodes, Metadata, storage devices (SSDs, HDDs)
• Performance/Optimization: Addressing Fragmentation, caching.
• Backup/Recovery: Redundancy, Self-healing.
• Emerging Technologies: NVMe, ZFS, and BTRFS
• Directories/File Organization: Directory Structures, Links (Hard, Symbolic), Sectors/Blocks
• Distributed Systems Concepts: Fault Tolerance, Data Consistency, Scalability

Terminology in Computing (e.g., Program, Process, Thread)

• Program: Set of instructions
• Process: An instance of a program in execution
• Thread: The smallest unit of processing within a process

Concurrency vs. Parallelism

• Concurrency: Managing tasks concurrently, not simultaneously
• Parallelism: Performing multiple tasks simultaneously, using multiple processors

Multithreading and Hyperthreading

• Multithreading: Utilizing multiple threads within a single program
• Hyperthreading: Enables multiple threads to run on a single processor

Inter-Process Communication (IPC)

• Methods for processes to communicate and synchronize (e.g., sockets)

Multitasking vs. Multithreading

• Multitasking: Operating system manages multiple processes
• Multithreading: Threads within a single process

Multiprocessor Systems

• Systems using multiple processors to increase efficiency and throughput

Shared Memory

• A method of inter-process communication (IPC) that allows multiple processes to access the same memory space.

Testing

• Testing for reliability and functionality by verifying that software meets the specified needs.

Security

• Security measures for protecting systems from unauthorized access and threats.
• Tactics: Identifying potential security breaches and implementing mitigation strategies

This quiz covers the essential concepts of operating systems, including their definitions, types, core components like the kernel and shell, as well as random access memory (RAM) and process management. Test your understanding of these key topics in computer science.