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1.1.Unix vs Linux History

Operating System Architecture (Unix vs Linux)

1. Operating System Layered Architecture

The diagram illustrates the hierarchical structure of any operating system, from the hardware components up to the user applications:

  1. Hardware (Blue Inner Layer):\ These are the physical components of the computer (CPU, memory, hard drive, input/output boards).\ They form the foundation on which everything else relies.

  2. Kernel (Green Layer):\ The core of the operating system, acting as the brain between hardware and software.\ Its main function is to manage system resources.

  3. Shell (Red Layer):\ The interface that allows users or applications to interact with the kernel.\ It receives user commands and passes them to the kernel for execution (e.g., Bash or PowerShell).

  4. Applications (Gray Outer Layer):\ Programs used by users to perform specific tasks (such as browsers, text editors, or databases).\ They rely on the shell and kernel to operate and access hardware resources.

2. Kernel Functions

The kernel is the most critical part of the OS, with these primary functions:

  • Resource Management: Overall management of system resources (e.g., power distribution and peripheral control).

  • Memory Management: Allocating and managing RAM among different processes.

  • Storage Management: Handling the file system and access to data stored on the hard drive.

  • Job Scheduling: Determining the order of process execution on the CPU to ensure multitasking efficiency.

3. Quick Comparison (UNIX vs Linux)

The diagram highlights key differences and characteristics of UNIX and Linux:

UNIX:

  • Closed Source: The system source code is not publicly available for modification or review.

  • Explanation: UNIX is the original operating system developed by AT\&T Bell Labs in the 1960s–70s and serves as the foundation for other similar systems (e.g., macOS, Solaris).

Linux:

  • Linus Torvalds: The developer who started the Linux kernel project in 1991.

  • Open Source: The source code is freely available for anyone to use, modify, and distribute.

  • Multitasking: The ability to run multiple programs and processes simultaneously (also a feature shared with most modern UNIX systems).

  • Explanation: Linux is a UNIX-like OS built on a kernel developed by Linus Torvalds and a community of developers. It is free, open-source, and widely used.