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

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Using Proximity, White Space, Alignment, Contrast, and Repetition in Design

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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" »

Computer Architecture Basics and Performance

Posted by thorng and classified in Computers

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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 (texec, 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 (tcpu(user)): Seconds the CPU spends executing the program's instructions.
  • System CPU Time (tcpu(sys)): Seconds the CPU spends executing OS (kernel) instructions
... Continue reading "Computer Architecture Basics and Performance" »

Statistics and Trigonometry: Student Weights and Cosine Function

Classified in Computers

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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" »

Webpage Design and Security Threats

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Design of Webpages

There are 2 distinct phases:

  • Layout: it organizes written and multimedia spaces and contents.
  • Interface: is the set of commands and methods that facilitate the interaction between the user and the system

We cannot move ahead with the creation of a web page without knowing what we want to show, the topic and the quantity of information that we will put in it. We shall also decide the title of the web page, its header and its logo, since they will give a sensation of continuity and greater professionalism.

CMS

The Content Management Systems (CMS) are applications installed on the server that enable us the creation of dynamic web pages and allow us to design the site independently of the content. When we administer a CMS, we define... Continue reading "Webpage Design and Security Threats" »

"entirely belongs to" shareholding

Classified in Computers

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Chapter 1 Introduction to Services

3.1. Service Terminology Service

a service is a software program that makes its functionality available via a technical interface, called a service contract.

Image

Figure 3.1. The symbol used to represent an abstract service.

Service Contract

The symbol used to represent a service contract is displayed in Figure 3.2.

Image

Service Capability

A service contract can be broken down into a set of service capabilities, each of which expresses a function offered by the service to other software programs.

Image

Figure 3.4. A Purchase Order service contract with four service capabilities.

Service Consumer

A service consumer is software program when it accesses and invokes a service—or, when it sends a message to a service capability


Service

... Continue reading ""entirely belongs to" shareholding" »

10 Usability Heuristics for User Interface Design

Classified in Computers

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1. Visibility of System Status

The system should always keep users informed about what is going on, through appropriate feedback within a reasonable time.

2. Match Between System and the Real World

The system should speak the user's language, with words, phrases, and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.

3. User Control and Freedom

Users often choose system functions by mistake and will need a clearly marked "emergency exit" to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.

4. Consistency and Standards

Users should not have to wonder whether different words, situations, or actions... Continue reading "10 Usability Heuristics for User Interface Design" »

Computer Hardware and Operating System Fundamentals

Classified in Computers

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Microprocessor

A microprocessor is an integrated circuit with millions of tiny transistors that process instructions and data from memory.

  • Clock rate: The microprocessor's speed.
  • Number of bits: The amount of data a computer can process at once.

Memory

  • RAM: Main memory for temporary data storage.
  • ROM: Memory for startup programs and diagnostics.
  • Cache: Stores frequently used data for the microprocessor.

Storage

  • Hard disk: Device for permanent information storage.

Operating System

The operating system is a set of commands and programs that control basic computer processes and enable other programs to run.

  • Manages the microprocessor, coordinating computer work.
  • Manages memory and storage systems.
  • Provides a user interface.
  • Enables communication between applications
... Continue reading "Computer Hardware and Operating System Fundamentals" »

Exploring Basic Linux System Calls

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Problem Statement

Explore the usage of basic Linux system calls.

Process Management System Calls

The system calls to manage processes are:

  • fork(): Used to create a new process.
  • exec(): Executes a new program.
  • wait(): Waits until the process finishes execution.
  • exit(): Exits from the process.

System calls used to get process IDs are:

  • getpid(): Gets the unique process ID of the process.
  • getppid(): Gets the parent process's unique ID.

Stat System Call

The stat system call retrieves information about files, specifically from their inodes. For instance, to get a file's size and name, you would typically use stat. Let's illustrate with a C code snippet (src/ls1.c):

#include<stdio.h>
#include<dirent.h>
#include<cstdlib>

struct dirent *dptr;
... Continue reading "Exploring Basic Linux System Calls" »

Java Programming Concepts and Examples

Classified in Computers

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Palindrome

  1. Start
  2. Read the string
  3. Calculate the length of the string
  4. Initialize rev
  5. Initialize i=length=1
  6. Repeat until i>=0
    1. rev=rev+char at position I of the string
    2. i=i-1
  7. If string=rev:print “palindrome”
  8. Else print “not palindrome”
  9. Stop

import java.util.Scanner; import java.util.Scanner; class Test { public static void main(String args[]){ Scanner sc = new Scanner(System.in); System.out.print("Enter the String:"); String str = sc.nextLine(); int flag = 0; int len = str.length(); for(int i=0;i


Inheritance

  1. Create a class employee with given variables and method print the salary
  2. Create two sub classes of class employee named officer and manager include the variable specilaization in officer class and department in manager class
  3. Create a class with main
... Continue reading "Java Programming Concepts and Examples" »

Understanding Operating Systems: Functions, Performance, and Multithreading

Classified in Computers

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WEEK 1: Software that Manages Computer Hardware

Operating System as an Abstract Machine, Service Provider, and Resource Manager. OS Objectives: Convenience, Efficiency, and Ability to Evolve.

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Performance Indices

Arrival Time, Service Time, Turnaround Time, Normalized Turnaround Time. First-Come-First-Served (FCFS) Scheduling Policy.

Microprocessor and DMA Activity

Impact of Microprocessor Bus Configuration and DMA Activity on System Speed.

Memory System and Cache

Cache and Main Memory Access Time, Average Access Time Calculation.

A colorful bar chart with numbers  Description automatically generated with medium confidence

iOS and Android

Similarities and Differences between iOS and Android.

Job Execution and CPU Utilization

CPU Utilization for Uniprogramming and Multiprogramming.

Direct Memory Access (DMA)

Coordination, Memory Operations Completion,... Continue reading "Understanding Operating Systems: Functions, Performance, and Multithreading" »