Notes, summaries, assignments, exams, and problems for Computer science

Understanding Network Fundamentals

What Is a Router?

A router is a networking device that connects two or more networks and forwards data packets between them based on their IP addresses. It determines the best path for data to travel across networks.

Understanding SSH (Secure Shell)

SSH (Secure Shell) is a network protocol used to securely access and manage remote computers over an unsecured network. It encrypts the communication between client and server to ensure security.

What Are IEEE Standards?

IEEE Standards are technical standards developed by the Institute of Electrical and Electronics Engineers for designing and developing hardware, software, and networking technologies to ensure compatibility and interoperability (e.g., IEEE 802 standards...

Linux and Operating Systems Fundamentals

• 1. CD-ROM Directory: The CD-ROM contains a directory called /fortycdrom/data.
• 2. Permissions: -rwxr-xr applies to everyone and members.
• 3. Process Control: ID 42000 — kill -9.
• 4. Modern Operating Systems: Applies to all.
• 5. Child Process: Identified by the process ID.
• 6. 11-Bit Processor: Maximum value is 2047.
• 7. Block Special File: Represents a hard disk drive.
• 8. POSIX Compliant: There are different standards.
• 9. Code Execution: The following code crashes.
• 10. Bash Command: alias bubble.
• 11. Linux Shell: pwd prints the current working directory.
• 12. Shell Commands: chown is used for ownership.
• 13. Virtual Machine: Utilizes CPU and memory resources.
• 14. File Names: ls -al lists files including their names.
• 15.

Unit I — Computer Fundamentals

1. Generations of Computers

Computers have evolved significantly over time, categorized into generations based on technological advancement. The first generation (1940–1956) relied on vacuum tubes, which made computers bulky, expensive, and heat-prone. These machines used machine language and had limited speed, processing only basic calculations. The second generation (1956–1963) replaced vacuum tubes with transistors, reducing size, cost, and power consumption. Assembly language became popular during this era, making programming easier. The third generation (1964–1971) introduced integrated circuits (ICs), improving reliability and processing speed while reducing physical size. High-level programming languages...

The Transport Layer: OSI Model Layer 4

The Transport Layer is the 4th layer of the OSI model, providing process-to-process communication between applications running on different hosts. It ensures reliable, error-free, and ordered delivery of data.

Main Services of the Transport Layer

• Process-to-Process Delivery: Uses port numbers to deliver data from a specific process on the sender to a specific process on the receiver.
• Segmentation and Reassembly: Divides large messages into smaller segments for transmission and reassembles them at the destination.
• Connection Control: Supports connection-oriented communication (TCP) and connectionless communication (UDP).
• Flow Control: Prevents the sender from overwhelming the receiver with too much data by using

C++ Recursive Function Examples

countUp — Print Increasing Numbers

#include <iostream>
using namespace std;

void countUp(int n) {
    if (n == 0) return;
    countUp(n - 1);
    cout << n << " ";
}

int main() {
    int n;
    cout << "Enter a positive integer: ";
    cin >> n;
    countUp(n);
    return 0;
}

summation — Sum of 1 to n

#include <iostream>
using namespace std;

int summation(int n) {
    if (n == 0) return 0;
    return n + summation(n - 1);
}

int main() {
    int n;
    cout << "Enter a positive integer: ";
    cin >> n;
    cout << summation(n);
    return 0;
}

power — Exponentiation (Recursive)

#include <iostream>
using namespace std;

int power(int n, int e)

Hexadecimal Integer Grammar Analysis

Consider the following grammar for hexadecimal integers:

• <hex literal> ::= 0x<number>
• <number> ::= <number><number> | <digit>
• <digit> ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F

The string 0xF3 is an element of the language generated by this grammar.

Derivation Sequences and Parse Trees

1. How many distinct derivation sequences exist for this string?

There exist 6 distinct derivation sequences:

• <hex literal> ⇒ 0x<number> ⇒ 0x<number><number> ⇒ 0x<digit><number> ⇒ 0x<digit><digit> ⇒ 0xF<digit> ⇒ 0xF3
• <hex literal> ⇒ 0x<number> ⇒ 0x<number><number> ⇒ 0x<number&

Define Machine Learning. Briefly explain the types of learnings.

Machine Learning (ML) is a branch of Artificial Intelligence (AI) that enables computers to learn automatically from data and improve their performance on a task without being explicitly programmed. It focuses on developing algorithms that can identify patterns and make predictions or decisions.

Types of Learning in Machine Learning:

1. Supervised Learning:

   • The model is trained using labeled data (input-output pairs).

   • It learns the relationship between input and output to make predictions.

   • Examples: Classification (e.G., spam detection), Regression (e.G., price prediction).

2. Unsupervised Learning:

   • The model is trained using unlabeled data (no predefined output).

   • It finds hidden patterns or

Operating System Concepts and Core Functions

Process Management

Process management involves managing the execution of programs (processes), including creation, scheduling, termination, and communication between processes.

Memory Management

Memory management requires the OS to allocate and manage memory resources efficiently for different processes. This includes virtual memory techniques and page-replacement algorithms.

CPU Scheduling

CPU scheduling determines which process gets access to the CPU at any given time. Effective scheduling is crucial for system performance and fairness. Common algorithms include:

• Round Robin (RR)
• Shortest Job First (SJF)
• First-Come, First-Served (FCFS)

Inter-Process Communication (IPC)

Inter-process communication (IPC) enables...

Obtener elementos del DOM

const resultsContainer = document.getElementById('results');
const favoritesContainer = document.getElementById('favorites');
const readContainer = document.getElementById('read');

Buscar libros en OpenLibrary usando fetch().then()

function fetchBooks(query, limit = 10, callback) {
  fetch(`https://openlibrary.org/search.json?q=${encodeURIComponent(query)}&limit=${limit}`)
    .then(res => res.json())
    .then(data => {
      const books = data.docs || [];
      callback(books);
    })
    .catch(err => {
      console.error("Error fetching books:", err);
    });
}

Guardar en localStorage si no está duplicado

function saveToLocalStorage(key, book) {
  const stored