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

Operating System Fundamentals

CPU Scheduling Algorithms

CPU scheduling algorithms determine the order in which processes are executed by the CPU. Each algorithm has distinct characteristics and trade-offs.

First-In, First-Out (FIFO)

This scheduling algorithm processes tasks in the order they arrive. While simple, its main disadvantage lies in potential performance bottlenecks, as a long process can block shorter ones, leading to inefficient CPU utilization.

Shortest Remaining Time (SRT)

A preemptive version of Shortest Job First (SJF). If a new process arrives with a shorter remaining execution time than the currently running process, the CPU switches to the new, shorter process. This aims to minimize average waiting time.

Shortest Job First (SJF)

Programming Fundamentals

Programming in computing involves automatic data processing and communication. Computers perform arithmetic and logical operations based on instructions, which collectively form a program.

Programming Languages

A programming language is a character set with a specific syntax used to create instructions that a computer can interpret.

Low-Level Languages

These languages are closest to the computer's understanding (binary code). Their characteristics include using characters closely related to the computer's internal operations (bits).

Machine Language

Machine language is one of the lowest levels. It uses the language of 1s and 0s, and each processor has its own specific machine language.

Assembly Language

Assembly language uses... Continue reading "Fundamentals of Computer Programming Concepts" »

The Graphics Card

1. What are Graphics Cards?

A graphics card is the hardware component of a computer that generates the image displayed on the monitor. The graphics card has evolved from a mere interface between the microprocessor and the display, which simply translated information consisting of an 80x24 character screen into an analog signal compatible with the monitor, to managing images with resolutions of 1024x768 pixels or more, with millions of possible colors and refresh rates over 70 Hz.

Current graphics cards have their own dedicated CPU for graphics operations and their own RAM, whose capacity is approaching and may even exceed that of the system.

2. Components of a Graphics Card

A graphics card has three main components:

• The graphics

This program demonstrates how to draw polygons using Bresenham's line algorithm in C. It utilizes the graphics.h library for graphics operations.

Code Overview

The program consists of several functions:

• main: The main function initializes the graphics mode, reads polygon coordinates, draws the polygon, and waits for a mouse click before closing the graphics window.
• mostrarEjes: Draws the X and Y axes on the screen.
• leerCoordenadasPoligono: Prompts the user to enter the number of vertices and their coordinates for the polygon.
• dibujarPoligono: Iterates through the vertices and draws the polygon by connecting consecutive points using Bresenham's line algorithm.
• lineaBresenham: Implements Bresenham's line algorithm to draw a line between two points.
• dibujarPunto:

Understanding Network Protocol Families

While the OSI model defines a comprehensive reference for network study, not every commercial network fully adopts OSI designs. Instead, many networks are built upon specific technologies and proprietary protocols.

NetWare Family

Manufactured by Novell, NetWare was once among the most widely used network systems worldwide. It was renowned for its high performance and capacity for growth.

NetBEUI Family

Microsoft has developed several operating systems that utilize NetBEUI (NetBIOS Extended User Interface) for communications within local area networks. Originally an IBM protocol introduced in 1985, NetBEUI provides a foundational basis for building peer-to-peer networks.

AppleTalk Family

AppleTalk is the network... Continue reading "Understanding Network Protocols and the OSI Model" »

POP3 Protocol Essentials

POP3 Functionality: Email Retrieval

The Post Office Protocol version 3 (POP3) server is designed primarily for retrieving emails. It facilitates communication where the client sends commands and receives responses from the server.

Key Features of POP3

• To access and review emails, a dedicated email client program such as Outlook or Thunderbird is required.
• The server downloads all email information directly to the client's local hard disk. Consequently, the server typically does not retain any copy of the mail after download, making it a 'download and delete' protocol.
• It is a simple, client-server protocol primarily focused on mail retrieval.

POP3 Synchronization and Response Codes

POP3's design for command verification is... Continue reading "Understanding POP3: Email Retrieval Protocol Fundamentals" »

Activating the Buffer Function in GIS

If you want to implement the buffer function and it is not active, what must you do to activate it? You must designate the units as follows:

• View -> Properties

Cartographic considerations must be made before an operation. The influence or buffer area must be activated as units are working.

Modifying Erroneous Values in a GIS Database

How can you modify an erroneous value in a database?

1. Table / Start Editing
2. With the pen tool, change the invalid data.
3. Table / Stop Editing

Deleting a Field in a GIS Database

How do you delete a field in a database?

• Edit / Delete Field

Deleting a Record in a GIS Database

How can you delete a record in a database?

• Edit / Delete Records

Invoking the Clip Command

What is required to invoke... Continue reading "Mastering GIS Operations: Essential Techniques and Troubleshooting" »

1. Computer System

The set of physical elements (Hardware) and software (Software) that allow information processing.

2. Physical Subsystem

Commonly known as hardware.

3. Logical Subsystem

Referred to as software.

4. Computer

An electronic device capable of processing data, performing load, arithmetic, and logic operations without human intervention.

5. Informatics

The science that studies the automatic and rational treatment of information.

6. Automatic and Rational

• Automatic: Tasks are performed by machines.
• Rational: Processes follow human reasoning.

7. Central Processing Unit (CPU)

Responsible for implementing programs and comprises the main memory, control unit, and arithmetic-logic unit.

8. Supercomputer

A specialized machine designed for tasks requiring... Continue reading "Understanding Computer Systems: Hardware, Software, and Key Concepts" »

Communication Modes

Operability:

• Simplex Communication: Clearly defined transmitter and receiver functions. Transmission occurs in one direction only. Example: a TV broadcast using a single physical channel and a single unidirectional logical channel.
• Half-Duplex Communication: Two-way communication where sender and receiver roles are interchangeable, but transmission is not simultaneous. When one device sends, the other must receive. It uses one physical channel and a bidirectional logical channel.
• Full-Duplex Communication: Bidirectional and simultaneous communication. Sender and receiver roles are not strictly defined.

Data Circuit Components

Circuit Data:

• Data Terminal Equipment (DTE): The source or destination of information.
• Data Circuit-Terminating

Image Processing

Imaging Technique

• Bitmap (Raster): Formed by pixels, each with a color. Programs: GIMP, Photoshop. Formats: GIF, JPEG, BMP, TIFF, PNG, PCX (Paintbrush), RAW, TGA, PSD (Photoshop), XCF (GIMP).
• Vector: Obtained using lines. Programs: Corel Draw, OpenOffice.org Draw, AutoCAD, QCad. Formats: DXF, CDR, DWG, ODG/SXD, SWF, AI, SFHx.
• 3D: Three-dimensional figures. Widely used in games. Programs: Virtual Hammer.

Memory Cards

• SD
• MMC
• XD
• Memory Stick

Image Properties

• Color Depth: Total number of bits used to encode an image. More depth means more shades.
• Brightness: Related to light intensity emitted over a given area.
• Contrast: Brightness difference between the maximum and minimum brightness.

Color Specification Systems

• RGB (Red, Green, Blue): Used