Operating Systems

An Operating System (OS) is the fundamental system software that manages computer hardware, software resources, and provides common services for computer programs. It acts as an intermediary between the user of a computer and the computer hardware, ensuring that the system operates efficiently and reliably.

The Evolution: From Batch to Distributed

The history of operating systems traces the evolution of computing hardware itself.

Batch Processing: Early systems executed jobs in batches without user interaction.
Time-Sharing: The advent of Unix introduced multi-tasking and multi-user capabilities, defining the POSIX standards still in use today.
Personal Computing: The GUI revolution (Mac OS, Windows) democratized access to computing power.
Mobile & Embedded: iOS and Android brought powerful OS capabilities to low-power, touch-based devices.
Cloud & Virtualization: Modern hypervisors and container orchestration engines (like Kubernetes) act as distributed operating systems managing clusters of resources.

Architectural Principles

To understand an Operating System, we must analyze its core components and how they manage resources:

Kernel: The core component that has complete control over everything in the system. It handles memory management, process scheduling, and hardware abstraction.
File System: The method and data structure that the OS uses to control how data is stored and retrieved (e.g., ext4, NTFS, APFS).
Process Management: The capability to execute programs, switch contexts between tasks (scheduling), and manage inter-process communication (IPC).
Memory Management: Virtual memory, paging, and swapping techniques that allow software to use more memory than is physically available.
User Space: The environment where user applications run, isolated from the critical Kernel Space to prevent system crashes.

The Evolution: From Batch to Distributed

Architectural Principles

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