Understanding Computers and Programming

Basics of Computers

• CPU (Central Processing Unit)
  • Piece of silicon with transistors (microscopic switches)
  • Operates on binary (0 and 1, on or off states)
  • Bit: Value of a switch; Byte: Group of 8 bits (256 combinations)
• Binary and Hexadecimal Systems
  • Binary represents powers of 2
  • Hexadecimal (0-9, a-f) is more readable than binary

Computer Operations

• Logic Gates
  • Electronic circuits performing Boolean algebra
• Character Encoding
  • ASCII assigns binary numbers to characters

Operating Systems

• Manages interactions between hardware and applications
• Examples: Windows, Linux, MacOS

Machine Code & CPU Execution

• CPUs execute instructions in machine code
• Requires RAM to store data; CPU executes instructions in cycles
• CPU speed: Measured in GHz, can be overclocked
• Multiple cores and threads for parallel processing

Programming Languages

• Translates human-readable code to machine code
• Interpreted Languages (e.g., Python): Executed line by line
• Compiled Languages (e.g., C, Go): Entire program converted to machine code

Programming Tools

• Variables: Hold data values, with different data types
• Data Types: Characters, strings, integers, floating-point numbers
• Pointers: Store memory addresses, enabling pointer arithmetic
• Memory Management
  • Low-level: Manual allocation (e.g., C)
  • High-level: Automatic garbage collection (e.g., Python)

Data Structures

• Arrays: Contiguous memory storage, fixed size
• Linked Lists: Nodes with pointers, dynamic size
• Stacks: Last in, first out
• Queues: First in, first out
• Hash Maps: Key-value pairs, use hash functions
• Graphs: Nodes connected by edges, useful for networks
• Trees: Hierarchical structures, binary trees for efficient search

Algorithms

• Functions: Perform operations, use recursion
• Loops: While and for loops for iteration
• Optimization: Memoization to save computation
• Complexity: Analyzed with Big O notation

Programming Paradigms

• Declarative vs. Imperative
• Object-Oriented Programming (OOP)
  • Classes and objects
  • Inheritance and polymorphism

Advanced Concepts

• Machine Learning: Learning from data via models
• Internet and Web
  • Networks and IP addresses
  • HTTP and browser interactions
  • APIs and databases
• Security
  • SQL injection attacks risk

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These notes summarize key concepts in computer science and programming as presented in the lecture, covering hardware basics, programming languages, data structures, algorithms, and more advanced topics like machine learning and internet technology.