Lecture Notes on Computers and Programming

Jul 26, 2024

Understanding Computers and Programming

Overview

  • Computers operate through basic principles, combining metal components to perform complex tasks.
  • Central Processing Unit (CPU) is crucial in computers.

CPU and Binary System

  • CPU: A silicon chip with billions of transistors (microscopic switches).
  • Bits and Bytes:
    • Bit: A binary value (0 or 1).
    • Byte: 8 bits, allowing 256 combinations.

Binary Counting

  • Binary: Base-2 number system (0 and 1).
  • Hexadecimal: Base-16 number system (0-9, A-F), more readable than binary.

Logic Gates and Boolean Algebra

  • Logic Gates: Circuit based on logical statements (AND, OR, NOT).
  • Boolean Algebra: Used for data operations in binary.

Data Representation

  • Character Encoding (e.g., ASCII): Maps binary numbers to characters.
  • Operating Systems manage how hardware and applications interact.

Memory and Machine Cycle

  • Random Access Memory (RAM): Temporary storage for data/instructions.
  • Machine Cycle:
    1. Fetch from memory.
    2. Decode instructions and data.
    3. Execute and store the result.
  • Modern CPUs can perform billions of cycles per second.

Programming Languages

  • Shell: Interface that exposes the kernel, allowing user commands.
  • Programming languages provide abstraction, turning high-level code into machine code.
    • Interpreted languages (e.g., Python) vs. compiled languages (e.g., C, Go).

Variables and Data Types

  • Variables: Named storage for values.
  • Data Types:
    • Text: Characters and strings.
    • Numbers: Integers, floating point numbers.
    • Pointers: Variables holding memory addresses, allowing pointer arithmetic.

Memory Management

  • Manual allocation and freeing of memory in low-level languages.
  • Segmentation Faults: Accessing illegal memory locations.
  • Memory Leaks: Allocated memory not freed leads to performance issues.
  • Garbage Collectors: Automatic memory management in high-level languages.

Data Structures

Arrays

  • Contiguous memory storage, fixed size.

Linked Lists

  • Flexible, non-contiguous nodes with pointers.

Key Data Structures

  • Stacks: Last In, First Out (LIFO).
  • Queues: First In, First Out (FIFO).
  • Hash Maps: Collections of key-value pairs with potential for collisions.
  • Graphs: Nodes connected by edges.
    • Search algorithms: Breadth-first search vs. Depth-first search.
  • Trees: Hierarchical structure, e.g., file system or binary search trees.

Algorithms

  • Basic Definitions: Step-by-step instruction for solving a problem.
  • Function: Takes inputs, processes them, and returns an output.
  • Control Structures:
    • Conditional statements (if-else).
    • Loops: While and for loops.
    • Recursion: Functions calling themselves with a base condition to prevent overflow.

Performance and Complexity

  • Big O Notation: Measures time and space complexity of algorithms.
    • Focus on trends as input size grows.
  • Brute Force vs. Divide and Conquer: Choosing efficient and smarter approaches to problem-solving.

Programming Paradigms

  • Declarative vs. Imperative Programming: What vs. How.
  • Object-Oriented Programming (OOP):
    • Classes and objects with methods and properties.
    • Inheritance and Polymorphism for code reuse and flexibility.

Machine Learning

  • Definition: Teaching computers without explicit programming.
  • Process involves training data, algorithm selection, and error minimization.

Internet and Web Development

  • Network of interconnected computers.
  • IP Address: Unique identifier for each computer.
  • Data Transfer: TCP protocols break messages into packets for transmission.
  • Web Structure:
    • HTML (content), CSS (style), JavaScript (functionality).
  • HTTP Request/Response: Communication between client and server.
    • HTTP Status Codes: Indicate response status.

Database Management

  • Relational Databases: Use tables to organize data with primary and foreign keys.
  • SQL: Language for managing and querying databases.
    • Caution against SQL injection attacks.

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