Week 1: Computer Architecture & OS Basics

The Machine Under the Hood

Before you can secure a system (or exploit it), you must understand what it is. A computer is not magic; it is a collection of components working in precise synchronization.

1. Hardware Components

• CPU (Central Processing Unit): The brain. It executes instructions. Modern CPUs have multiple "cores" to do multiple things at once.
• RAM (Random Access Memory): Short-term memory. It's fast but volatile (data is lost when power is cut). Programs live here while they are running.
• Storage (HDD/SSD): Long-term memory. Slower than RAM but persistent. Your OS and files live here.

2. The Operating System (OS)

The OS is the software that manages the hardware. It sits between the user's applications and the physical metal.

• The Kernel: The core of the OS. It has complete control over everything in the system. It operates in "Ring 0" (highest privilege).
• User Space: Where your applications (browser, Word, games) run. This is "Ring 3" (lowest privilege). This separation prevents a crashing web browser from taking down the entire computer.

3. File Systems

Data on a drive is just a sea of 1s and 0s. A File System is the map that organizes that data into files and folders.

• NTFS (New Technology File System): The standard for Windows. Supports permissions (ACLs) and encryption.
• EXT4: The standard for most Linux distributions. Robust and efficient.