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)

1. Understanding Short and Long Strings

Short strings have a fixed length, not exceeding 245 characters. They are declared as follows:

• VAR S1: ShortString;
• VAR S2: STRING[25];

Long strings are allocated dynamically and are limited only by available memory. They are declared as:

• VAR S1: STRING;

2. What Are Parameters?

A parameter is a value passed to a function or procedure to be processed.

3. Parameter Passing: Value vs. Reference

Passing by Value: A copy of the original variable is created; the original value remains unchanged.

Passing by Reference: No copy is created; the procedure works directly with the original variable.

• Value: PROCEDURE REVIEW(NAME: STRING);
• Reference: PROCEDURE REVIEW(VAR NAME: STRING);

4. Functions vs. Procedures

• Function: A code

Understanding Core AI Search Algorithms

Best-First Search

If the node that receives the best evaluation is expanded first, then we are performing a Best-First Search. This algorithm expands what appears to be the best option according to its evaluation function. This function takes into account all nodes seen so far to make its decision.

Breadth-First Search

Breadth-First Search evaluates each node at a certain level before moving on to the next level. It is an optimal algorithm, seeking the shortest solution path.

How Breadth-First Search Works

It searches the entire graph or sequence without considering the goal until it is found. This algorithm does not use a heuristic. From an algorithmic point of view, all child nodes obtained by expanding a... Continue reading "Pathfinding & AI Search Algorithms: Best-First, Breadth-First, Depth-First, A*" »

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" »

Web Page Creation

Application of Hyperlinks

A hyperlink is a cross-reference to another document. It consists of a point (the object where you insert the hyperlink) and a destination (the document or section displayed when the link is activated).

There are several ways to create hyperlinks:

• Internal Hyperlinks: Links to a specific part of the same document. To create these, you must first define the destination by setting an anchor or bookmark within the document.
• External Links: Links to other documents that are displayed, executed, or downloaded from the internet. These require specific attributes to define how the linked document is displayed.

Types of External Links

• Relative URLs: These refer to documents located in the same folder as your HTML

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The Relational Model

Relational Model: Defines a database in terms of objects, properties, and operations. Objects with the same structure and behavior belong to the same class, and classes are organized into hierarchies. Relational models have extended their models to incorporate object-oriented concepts. In 1970, Edward F. Codd published an article in which he argued that data should be inter-linked by natural and logical relationships inherent to the data, rather than through physical pointers.

Codd proposed a simple data model in which all data are represented in tables consisting of rows and columns. Codd also proposed two languages to manipulate data in tables:

• Relational algebra
• Relational calculus

The logical manipulation of data also makes... Continue reading "Relational Database Model Principles and Evolution" »