Computers and Their Functionality

Overview of Computers

• Computers appear complex ("Throw some metal in a box")
• Main component: Central Processing Unit (CPU)
  • Made of silicon with billions of transistors (microscopic switches)
  • States represented in binary (1 and 0)

Binary and Hexadecimal Systems

• Bit: Value at a switch, a single bit is insignificant
• Byte: Group of 8 bits (256 combinations)
• Binary: Used to store information
  • Each bit represents a power of 2
• Hexadecimal: More human-readable alternative to binary
  • Denoted by "0x"
  • Uses digits 0-9 and a-f

Logic Gates and Boolean Algebra

• Logic gates: Electronic circuits that perform logical operations (e.g., AND, OR)
• Circuits built from logic gates perform calculations based on Boolean algebra

Character Encoding

• ASCII: Maps binary numbers to characters
• Input devices provide instructions to the computer

CPU and RAM

• CPU executes instructions but lacks storage capability
• Random Access Memory (RAM): Temporary storage for data/instructions
  • Organized in a grid of bytes, accessed via addresses
• Machine Cycle Steps: 1) Fetch, 2) Decode, 3) Execute, 4) Store
  • Modern CPUs perform billions of cycles per second (measured in GHz)

Programming and Machine Code

• Instructions given in machine code (binary)
• Shell allows user interaction with the kernel
• Programming languages convert code to machine code
  • Interpreters (e.g., Python) vs. Compilers (e.g., C)

Variables and Data Types

• Variables: Hold values and have types (integer, float, string)
  • Floating point: Decimal can vary (using scientific notation)
• Pointers: Variables that store memory addresses
  • Pointer arithmetic allows navigation through memory

Memory Management

• Manual memory allocation in low-level languages (e.g., C)
  • Risks: Segmentation faults and memory leaks
• High-level languages (e.g., Python) use garbage collectors

Data Structures

• Arrays: Fixed-size lists of similar data types, fast retrieval
• Linked Lists: Dynamic, consisting of nodes with values and pointers
• Stacks: Last in, first out (LIFO) structure
• Queues: First in, first out (FIFO) structure
• Hash Maps: Key-value pairs with potential collisions

Graphs and Trees

• Graphs: Nodes connected by edges (directed/undirected)
  • Searching methods: Breadth-first search, Depth-first search
• Trees: Hierarchical data representation (e.g., file systems)
  • Binary search trees allow efficient searching

Algorithms and Complexity

• Algorithms: Step-by-step instructions to solve problems
• Big O notation: Measures time/space complexity
  • Examples: O(n) for linear algorithms, O(n!) for factorial growth
• Programming paradigms: Declarative vs. Imperative
  • Object-oriented programming: Encapsulates properties and methods

Machine Learning

• Teaching computers without explicit programming
  • Requires data, training/testing sets
  • Uses algorithms like neural networks to optimize performance

Internet Basics

• Network of computers connected via cables
• Unique IP addresses for each computer
• TCP for data transfer; packet loss may occur
• Web uses HTTP and URLs to access servers

Web Technologies

• Websites consist of HTML (content), CSS (style), JavaScript (functionality)
• HTTP response codes indicate status (e.g., 200 OK, 404 Not Found)

Databases

• Relational databases: Tables with rows (data points) and columns (attributes)
  • Primary key for unique identification, foreign key for relationships
• SQL used for database management
  • Risks of SQL injection attacks

Learning Resources

• Brilliant.org offers interactive lessons for programming and other subjects
• Free 30-day trial with an option for a premium subscription.