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

Programming Fundamentals

What is a Constant?

A constant is a data value that remains unchanged during the execution of a program.

Three Programming Constructs

The three fundamental programming constructs are: selection, iteration, and sequence.

Logical Operators

One example of a logical operator is AND.

• Operator: and
• Description: Logical AND: True if both operands are true.
• Syntax: x and y

Functions vs. Procedures

Difference: A function is typically used to calculate a value from a given input, while a procedure is a set of commands executed in a specific order.

Similarity: Functions must return a value, but in stored procedures, it is optional. Procedures can return zero or multiple values. Functions usually have only input parameters, whereas procedures... Continue reading "Programming Concepts: Constants, Constructs, and Operators" »

Arithmetic Operations in Java

Input Form

<% String num1Str = request.getParameter("num1"); String num2Str = request.getParameter("num2"); String operation = request.getParameter("operation"); if (num1Str != null && num2Str != null && !num1Str.isEmpty() && !num2Str.isEmpty() && operation != null) { double num1 = Double.parseDouble(num1Str); double num2 = Double.parseDouble(num2Str); double result = 0; switch (operation) { case "add": result = num1 + num2; out.println("

Result: " + result + "

"); break; case "subtract": result = num1 - num2; out.println("

Result: " + result + "

"); break; case "multiply": result = num1 * num2; out.println("... Continue reading "Java Arithmetic Operations Web App" »

HOSTàROUTER: 1

ENABLE

CONFIGURE TERMINAL

INTERFACE GIGABITETHERNET 0/0

IP ADDRESS 192.168.1.126 255.255.255.224

NO SHUTDOWN

EXIT

INTERFACE GIGABITEETHERNET 0/1

IP ADDRESS 192.168.1.158 255.255.255.240

NO SHUTDOWN

HOSTàSWITCH 2

ENABLE

CONFIFURE TERMINAL

INTERFACE VLAN 1

IP ADDRESS 192.168.1.157 255.255.255.240

NO SHUTDOWN

HOST/ROUTER 3

EXIT (LLEGAR AL CONFIGURE TERMINAL)

HOSTNAME MIDDLE

ENABLE SECRET CISCO

LINE CONSOLE 0

PASSWORD CLASS

LOGIN

EXIT

SECURITY PASSWORD MIN-LENGTH 10

SERVICE PASSWORD ENCRYPTION

IP DOMAIN-NAME CISCO

CRYPTON KEY GENERATE RSA

1024

EXIT

USERNAME CICLOS

LINE VTY 0 4

LOGIN LOCAL

TRANSPORT INPUT SSH

EXIT

INTERFACE GIBABITEETHERNET 0/0

IPV6 ADDRESS 2001:DB8:ACAD:A::1/64

IPV6 ADDRESS FE80::1 LIN

EXIT

GIBABITETHERNET 0/1

IPV6 ADDRESS 2001:DB8:ACAD:B::1/64

IPV6

A computer virus is a type of computer program that, when executed, replicates itself by modifying other computer programs and inserting its own code.^[1] When this replication succeeds, the affected areas are then said to be 'infected' with a computer virus.^[2][3]

Virus writers use social engineering deceptions and exploit detailed knowledge of security vulnerabilities to initially infect systems and to spread the virus. The vast majority of viruses target systems running Microsoft Windows,^[4][5][6] employing a variety of mechanisms to infect new hosts,^[7] and often using complex anti-detection/stealth strategies to evade antivirus software.^{[8][9][10][11]} Motives for creating viruses can include seeking profit (e.g., with ransomware), desire... Continue reading "Understanding Computer Viruses and Network Topologies" »

The Intel 8051 is an 8-bit microcontroller, meaning most available operations are limited to 8 bits. There are three basic "sizes" of the 8051: Short, Standard, and Extended. The Short and Standard chips are often available in DIP (Dual In-line Package) form, but the Extended 8051 models often have a different form factor and are not "drop-in compatible."

Key Features of the Intel 8051

• 4 KB on-chip program memory.
• 128 bytes on-chip data memory (RAM).
• 32 bytes devoted to register banks.
• 16 bytes of bit-addressable memory.
• 80 bytes of general-purpose memory.
• Four register banks.
• 128 user-defined software flags.
• 8-bit data bus.
• 16-bit address bus.
• 16-bit timers (usually 2, but may have more or less).
• 3 internal and 2 external interrupts.
• Bit as well as byte-

Javascript Continued

Proximity

Proximity is all about using visual spaces to show relationships in your content. We can group the items in blocks of text or elements in the graphic to take visual emphasis.

White Space

White space, also known as negative space, refers to the spaces between your content, between lines, and even the margins. White space defines and separates different sections.

Alignment

We can separate text boxes, images, etc. by imagining their content as a range inside of a grid. Centering the images to the text and using equal size margins can create a visually pleasing alignment.

Contrast

Contrast means that one item is different from another. We can create contrast using color, size, shape, or contrasting styles of text. Hierarchy, a visual technique... Continue reading "Using Proximity, White Space, Alignment, Contrast, and Repetition in Design" »

Key Network Concepts and Design Principles

Essential Network Terminology

Usability

The ease with which network users can access the network and its services. This includes goals for simplifying user tasks.

Management (Fault, Configuration, Accounting, Performance, Security)

The five key areas of network management: Fault Management, Configuration Management, Accounting Management, Performance Management, and Security Management.

Bandwidth

The data-carrying capacity of a circuit, measured in bits per second (bits/sec).

Throughput

The quantity of error-free data transmitted per unit of time by a circuit, measured in bits/bytes per second or packets per second.

Five Nines

High availability of service, commonly taken to mean 99.999% uptime.

Silent Failure

A

Introduction to Architecture

• Instruction Set Architecture (ISA): An assembly language programmer's view of the microprocessor.
• Assembler: Translates symbolic assembly language code into binary machine language code.

Computer Performance Metrics

• Execution Time (Response Time): Time to complete a program or task.
• Throughput (Bandwidth): Number of programs or tasks completed per time unit.
• Execution Time (t_exec, i.e., elapsed time, wall time, real time, response time): Elapsed seconds from start to finish. Includes:
  • Executing instructions
  • Disk access
  • Memory access
  • I/O activities
  • OS overhead
• User CPU Time (t_cpu(user)): Seconds the CPU spends executing the program's instructions.
• System CPU Time (t_cpu(sys)): Seconds the CPU spends executing OS (kernel) instructions

Weight of 30 Students - Minimum, Maximum, Average and Standard Deviation - 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

Maximum: 96

Minimum: 59

Average: 80.5333

Standard Deviation: 8.4516

Histogram

Plot the value of the cosine within [0 2π] with a step of π/20.

Label the axes and add a title.

Add to that graph the sine function. Use hold command.

Place legends to distinguish both graphic

x = 0:pi/20:2*pi

0 0.1571 0.3142 0.4712 0.6283 0.7854 0.9425 1.0996 1.2566

1.4137 1.5708 1.7279 1.8850 2.0420 2.1991 2.3562 2.5133 2.6704

2.8274 2.9845 3.1416... Continue reading "Statistics and Trigonometry: Student Weights and Cosine Function" »