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

Office Facilities and Personnel

• Assist: Be in charge of, describe, develop, explain how to use, hire (contatar), sell.
• Cafeteria: Car park, conference room, ground floor, kitchen, lobby, maintenance, reception, stockroom, toilet, top floor, warehouse.
• Appointment (cita): Business card, clerk (dependiente), do business, employee, employer, escalator, interview, name plate, receptionist, research and development department, title.

Administrative Tasks and Business Operations

• Answer incoming calls: Data entry, deliver the message, distribute the incoming mail, file documents (archivar), keep a log (mantener registro), keep track of (llevar registro), order supplies, prepare a presentation, receive visitors, schedule a meeting, screen a call, search

C# Project and Developer Management Controller

This document outlines the core logic for a C# controller designed to manage software projects and their associated developers. It demonstrates fundamental operations such as adding, finding, and listing projects and developers, ensuring data integrity by preventing duplicates.

GestorController Class Definition

The GestorController class serves as the central hub for managing project and developer data. It resides within the GestionProyectos.Controllers namespace and utilizes models from GestionProyectos.Models.

using GestionProyectos.Models; //Controllers-GestionP

namespace GestionProyectos.Controllers
{
    public class GestorController
    {
        public static List Projects { get; set; };

Phishing:

Hackers attempt to impersonate genuine organisations to fool the user into providing sensitive personal data. Emails are very official-looking, and they usually contain a link to a website which is an exact copy of the organisation's actual site, but it is operated by the criminals. When the user logs in with their details, the data is sent to the criminal. 

Guarding against phishing:

No reputable organisation would request personal details in an email or unsolicited phone call, because it does not need your sensitive data to access your account information. Never follow links to a bank/organisation- manually type it.

Trojan Horses:

Malware program that comes in disguise. Rely on tricking the user into downloading and running them. Involves...

Layered Protocols: Advantages and Disadvantages

Layered protocols are a fundamental concept in network design. Understanding their benefits and drawbacks is crucial for efficient system development.

Reasons for Using Layered Protocols

Using layered protocols offers several benefits, including:

• Breaking up the design problem into smaller, more manageable pieces.
• Allowing protocols to be changed without affecting higher or lower layers, promoting modularity and flexibility.

Disadvantages of Layered Protocols

Potential drawbacks of using layered protocols include:

• More overhead: This is due to added information or operations performed in each layer, which can increase processing and transmission costs.
• Information hiding: Information useful for other layers

5. A machine has a 32-bit address space and an 8-KB page. The page table is entirely in hardware, with one 32-bit word per entry. When a process starts, the page table is copied to the hardware from memory, at one word every 100 nsec. Lf each process runs for 100 msec (including the time to load the page table), what fraction of the CPU time is devoted to loading the page tables?

The page table contains 232 /213 entries, which is 524,288.  Loading the page table takes 52 msec. If a process gets 100 msec, this consists of 52 msec for loading the page table and 48 msec for running. Thus 52% of the time is spent loading page tables.

6. Suppose that a machine has 48-bit virtual addresses and 32-bit physical addresses. If pages are 4 KB, how many...

1. CalculatorInterface.java

The following code defines the Remote Interface for the calculator application.

import java.rmi.*;

public interface CalculatorInterface extends Remote {
    public int add(int num1, int num2) throws RemoteException;
    public int subtract(int num1, int num2) throws RemoteException;
    public int multiply(int num1, int num2) throws RemoteException;
    public int divide(int num1, int num2) throws RemoteException;
}

2. ServerCalculator.java

This class implements the CalculatorInterface and extends UnicastRemoteObject to handle remote calls.

import java.rmi.*;
import java.rmi.server.*;

public class ServerCalculator extends UnicastRemoteObject implements CalculatorInterface {
    public ServerCalculator() throws RemoteException

Internet Architecture and Core Protocols

The Three Layers of Internet Architecture

The internet architecture can be broadly classified into three layers:

1. Internet Backbones and High-Speed Network Lines: This first layer consists of Internet Backbones and very high-speed network lines. The National Science Foundation (NSF) created the first high-speed backbone in 1987 called NSFNET. It was a T1 line that connected 170 smaller networks together and operated at 1.544 Mbps (million bits per second). IBM, MCI, and Merit worked with NSF to create the backbone and developed a T3 (45 Mbps) backbone the following year. Backbones are typically fiber optic trunk lines. The trunk line has multiple fiber optic cables combined together to increase capacity.

Excel Practice Questions and Answers

1. The ________ displays the current cell mode, the page number, and the zoom buttons.

   Answer: Status bar

2. A text value in Excel is also referred to as a ________.

   Answer: Label

3. When you type text in a cell, it is ________.

   Answer: Left-aligned

4. Which of the following is NOT a way to create a formula?

   Answer: By using a Function button on the status bar

5. ________ is a procedure that determines which digit to the right of a number will be the last to be displayed.

   Answer: Rounding

6. Which of the following is NOT part of the Accounting Number Format?

   Answer: Three decimal places

7. Tiny charts embedded in a cell that display a visual trend summary alongside your data are called ________.

   Answer: Sparklines

8. What are the two contextual

Variables

Array

int myInts[6];
int myPins[] = {2, 4, 8, 3, 6};
int mySensVals[6] = {2, 4, -8, 3, 2};
char message[6] = "hello";

Bool

int LEDpin = 5;       // LED on pin 5
int switchPin = 13;   // momentary switch on 13, other side connected to ground
bool running = false;

void setup()
{
  pinMode(LEDpin, OUTPUT);
  pinMode(switchPin, INPUT);
  digitalWrite(switchPin, HIGH);      // turn on pullup resistor
}

void loop()
{
  if (digitalRead(switchPin) == LOW)
  {
    delay(100);                        // delay to debounce switch
    running = !running;                // toggle running variable
    digitalWrite(LEDpin, running);     // indicate via LED
  }
}

Char

char myChar = 'A';
char myChar = 65;      // both are equivalent

Double

Double precision...

MATLAB Statistical Analysis of Student Weights

Analyze the weight of 30 students to find the minimum, maximum, average, standard deviation, and plot a histogram.

>> a=[ 71 82 65 75 77 91 59 84 89 81 73 91 82 75 96 85 69 76 81 92 84 79 77 95 81 79 84 85 76 82]

a = Columns 1 through 12
    71 82 65 75 77 91 59 84 89 81 73 91

Columns 13 through 24
    82 75 96 85 69 76 81 92 84 79 77 95

Columns 25 through 30
    81 79 84 85 76 82

>> max(a)
ans = 96

>> min(a)
ans = 59

>> mean(a)
ans = 80.5333

>> std(a)
ans = 8.4516

>> hist(a)

Plotting Trigonometric Functions in MATLAB

Follow these steps to plot trigonometric functions:

• Plot the value of the cosine within [0, 2π] with a step of π/20.
• Label the axes and add