1. Introduction to Operating Systems and Computer Components

What Is an Operating System (OS)?

• Definition: An operating system (OS) is a collection of programs that manage the computer’s hardware and serve as an interface between the physical machine and the user’s applications (software).
• Functions of an OS:
  • Resource Management: Allocates the CPU (Central Processing Unit), memory, and other hardware resources among different programs.
  • Memory Management: Divides and protects memory areas for each application.
  • Peripheral Management: Manages input/output devices such as keyboards, mice, monitors, printers, etc.
  • File System Management: Organizes data storage, including file creation, reading, writing, and deletion.
  • Security Management: Controls user access and protects the system from unauthorized use.

Essential Computer Components

• Central Processing Unit (CPU): Executes instructions and performs calculations.
• RAM (Random Access Memory): Temporary storage for data and programs currently in use.
• ROM (Read Only Memory): Contains essential instructions for system startup.
• Input/Output Devices: Includes keyboards, mice, monitors, printers, etc.
• External Memory: Such as hard drives and CD-ROMs for long-term data storage.

2. Unix: History, Characteristics, and Architecture

History of Unix

• Origins:
  • Developed in 1969 at Bell Labs by Ken Thompson and Dennis Ritchie.
  • Inspired by the Multics system (MULTiplexed Information and Computing Service) developed at MIT.
  • Originally called “Unics” (Uniplexed Information and Computing Service) before evolving into “Unix.”
• Key Milestone: In 1973, Unix was rewritten in the C programming language, greatly enhancing its portability to new hardware platforms and contributing to its widespread adoption.

Characteristics of Unix

• Multitasking: Ability to run several processes (tasks) simultaneously.
• Multi-user: Supports multiple users concurrently, each having access to system resources.