Notes, summaries, assignments, exams, and problems for Computers

Items 551 - 560 of 1,109

ISO OSI and TCP/IP Networking Models Explained

Classified in Computers

Written on May 24, 2026 in English with a size of 3.98 KB

The ISO OSI Reference Model

Created in 1984 by ISO, the model consists of seven layers:

Layer 1: Physical Layer – Global connections, transmitting raw bits, no buffering.
Layer 2: Data Link Layer – Secured channels, reducing connection errors, structuring, and transmission controls.
Layer 3: Network Layer – Multiple connectivity, chosen quality, and transmission systems.
Layer 4: Transport Layer – Quality selection, recurring connections, user-to-user connection, and transparent data transport.
Layer 5: Session Layer – Manages sessions between users and machines.
Layer 6: Presentation Layer – Acts as the translator.
Layer 7: Application Layer – Includes protocols like HTTP.

TCP/IP Reference Model

The TCP/IP model is the standard family... Continue reading "ISO OSI and TCP/IP Networking Models Explained" »

Java Programming Concepts: A Comprehensive Guide

Classified in Computers

Written on September 26, 2024 in English with a size of 4.47 KB

A class is a template used to create objects and declare data types and methods in a program.
Public - Modifier used to declare classes and interfaces. Void - Method that returns no value. Main - Marks the start and end of program execution.
Scanner class - Used to get user input for types like String and Int.
Exceptions: Try-catch block, throw statement.
Inheritance provides a powerful and natural mechanism for organizing and structuring software programs. It improves clarity in the design of classes.
A subclass provides specialized behavior based on elements provided by the superclass. Using inheritance, programmers can reuse the code in the superclass many times.
Reading and Writing to Files:
1. Import java.io file.
2. File inputFile = new File("input.

... Continue reading "Java Programming Concepts: A Comprehensive Guide" »

C++ Object-Oriented Programming Concepts Explained

Classified in Computers

Written on May 11, 2026 in English with a size of 2.39 KB

Inheritance

Inheritance is the capability of a class to derive properties and characteristics from another class.

Deep Copy vs. Shallow Copy

Deep Copy

In a deep copy, an object is created by copying the data of all variables and allocating new memory resources with the same values. To perform a deep copy, you must explicitly define a copy constructor and assign dynamic memory if required. This also necessitates dynamic memory allocation in other constructors, requiring custom copy constructors and overloaded assignment operators.

box(box& sample) { 
  length = sample.length; 
  breadth = new int; 
  *breadth = *(sample.breadth); 
  height = sample.height; 
}

Shallow Copy

In a shallow copy, an object is created by simply copying the data of all... Continue reading "C++ Object-Oriented Programming Concepts Explained" »

Java Socket Programming and Nmap Network Scanning

Classified in Computers

Written on June 8, 2026 in English with a size of 3.5 KB

Java Socket Programming Implementation

Code: Server-Side

import java.io.*;
import java.net.*;

public class MyServer {
    public static void main(String[] args) {
        try {
            ServerSocket ss = new ServerSocket(6666);
            Socket s = ss.accept();
            DataInputStream dis = new DataInputStream(s.getInputStream());
            String str = (String) dis.readUTF();
            System.out.println("Message: " + str);
            ss.close();
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}

Client-Side Code:

import java.io.*;
import java.net.*;

public class MyClient {
    public static void main(String[] args) {
        try {
            Socket s = new Socket("localhost", 6666);

... Continue reading "Java Socket Programming and Nmap Network Scanning" »

Theory of Computation: Automata, and Regular Expressions

Classified in Computers

Written on October 8, 2024 in English with a size of 3.97 KB

Theory of Computation

Automata Theory

Automata theory is a theoretical branch of computer science and mathematics that deals with the logic of computation using simple machines called automata. The main goal of automata theory is to develop methods for describing and analyzing the dynamic behavior of discrete systems. Automata consist of states (represented by circles) and transitions (represented by arrows).

Finite Automata

A finite automaton is an abstract computing device and a mathematical model of a system with discrete input, output, states, and a set of transitions between states that occur on input symbols from an alphabet. Finite automata are the simplest machines for pattern recognition, used to characterize regular languages, analyze... Continue reading "Theory of Computation: Automata, and Regular Expressions" »

Excel 2016 Practice Questions and Answers

Classified in Computers

Written on June 13, 2026 in English with a size of 3.22 KB

Excel Practice Questions and Answers

The ________ displays the current cell mode, the page number, and the zoom buttons.
Answer: Status bar
A text value in Excel is also referred to as a ________.
Answer: Label
When you type text in a cell, it is ________.
Answer: Left-aligned
Which of the following is NOT a way to create a formula?
Answer: By using a Function button on the status bar
________ is a procedure that determines which digit to the right of a number will be the last to be displayed.
Answer: Rounding
Which of the following is NOT part of the Accounting Number Format?
Answer: Three decimal places
Tiny charts embedded in a cell that display a visual trend summary alongside your data are called ________.
Answer: Sparklines
What are the two contextual

... Continue reading "Excel 2016 Practice Questions and Answers" »

Data Manipulation and Visualization with R and the nycflights13 Dataset

Classified in Computers

Written on July 10, 2024 in English with a size of 3.64 KB

library(nycflights13)

library(tidyverse)

Data Manipulation with dplyr

Ordering Rows with `arrange()`

arrange(flights, year, month, day)

arrange(flights, desc(arr_delay))

Handling NAs

df <- tibble(x = c(5, 2, NA))

arrange(df, x)

arrange(df, desc(x))

Selecting Columns with `select()`

select(flights, year, month, day)

select(flights, year:day)

select(flights, -(year:day))

rename(flights, mes = month)

select(flights, time_hour, air_time, everything())

Creating New Variables with `mutate()`

flights_sml <- select(flights, year:day, ends_with("delay"), distance, air_time)

mutate(flights_sml, gain = arr_delay - dep_delay, speed = distance / air_time * 60)

Creating Functions with Vector Arguments

transmute(flights, dep_time, hour = dep_time %/% 100, minute = dep_time %

... Continue reading "Data Manipulation and Visualization with R and the nycflights13 Dataset" »

Digital Logic Design: Examples in VHDL

Classified in Computers

Written on July 12, 2024 in English with a size of 5.88 KB

Behavioral Architecture of a State Machine

This VHDL code describes the behavioral architecture of a state machine.

TYPE tipo_estado IS (DET0, DET0a1, DET1a0, DET1);

signal Estado_actual : tipo_estado;

signal Estado_siguiente : tipo_estado;

begin

Registro_estado: process (clk, reset)

begin

if reset='1' then Estado_actual <= DET0;

elsif (clk'event and clk='1') then

Estado_actual <= Estado_siguiente;

end if;

end process Registro_estado;

Cambio_Estado: process (Dato, Estado_actual)

begin

Estado_siguiente <= Estado_actual;

case Estado_actual is

when DET0 => if (Dato='1') then Estado_siguiente <= DET0a1;

else Estado_siguiente <= DET0;

end if;

when DET0a1 => if (Dato='1') then Estado_siguiente <= DET1;

else Estado_siguiente <= DET1a0;

end if;

... Continue reading "Digital Logic Design: Examples in VHDL" »

Microcontrollers: Architecture, Instruction Sets, and Interfacing

Classified in Computers

Written on November 15, 2024 in English with a size of 3.86 KB

Microcontrollers, Microcomputers, and Microprocessors

Microcontroller: Processor, memory, and I/O ports integrated on a single chip.

Microcomputer: A small computer.

Microprocessor: Example: Intel x86.

Von Neumann Architecture

Components:

Processor (Control Unit, ALU, Registers)
Memory (RAM - Volatile, ROM - Non-Volatile)
I/O

A single bus interconnects the processor, memory, and I/O.

RISC vs. CISC

Feature	CISC	RISC
Instruction Set	Complex Instruction Set Computer	Reduced Instruction Set Computer
Instructions	Multi-cycle, complex instructions	Mostly single-cycle, reduced instructions
Instruction Types	Many, varying length	Few, fixed length
Complexity	Hardware	Software
Code Size	Small	Large
Examples	Intel (x86), Freescale 9S12	MIPS, ARM, SPARC, PowerPC