Notes, summaries, assignments, exams, and exercises for Computer science for Secondary education

What is a Database?

A database is an organized collection of data, visualized as a container of information. The data is typically organized to model relevant aspects of reality. A Database Management System (DBMS) is a software package with computer programs that controls the creation, maintenance, and use of a database. It allows organizations to conveniently develop databases for various applications.

A database is an integrated collection of data records, files, and other objects. A DBMS allows different user application programs to concurrently access the same database. Typically, databases available on database servers are accessed through command-line or graphical user interface tools, referred to as front-ends; database servers are referred...

Vector Quantities

Some physical quantities, such as force and velocity, have both direction and magnitude. These are called vector quantities. The direction must be a part of the calculations related to these quantities. Examples include a displacement of 45 meters towards the north or a velocity of 95 km/h at 30° northwest.

Characteristics of Vectors

A vector is represented graphically by an arrow, consisting of the following elements:

• Point of application: The origin of the vector.
• Magnitude (Modulus): The value of the vector, represented by the length of the arrow drawn to scale.
• Line of action: The determined path of the vector, usually given in degrees relative to a reference.
• Direction: The orientation toward which the head of the arrow points.

Computer Science Fundamentals

Informatics is the science or technical study of technology that enables the automatic processing of information using electronic devices and computer systems.

Hardware and Software

• Hardware: All the physical parts that compose a computer.
• Software: A set of programs that execute tasks using the electrical circuits of the computer.

Software Types:

• System Software
• Software Development
• Application Software

Numbering Systems

• Decimal System: Each figure has a weight where its value depends on its location.
• Binary System: The most elementary coding system, using only "0" and "1". This coding avoids confusion in electronic systems because they identify only two possible states.

Bits and Bytes

A bit is an electronic signal that can...

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)

CARLOS HAYA IES Building Computer Room Web pages pag. 3

Website Structure Types

The basic structures we observe at any site are one of the following types:

Tree Structure

In this structure, there is a main page (the home page in English terminology) from which you can reach other sites on the Web. In this way, the pages come to be grouped into levels, so that to get from the first to the last, you must pass through the middle. It is a very hierarchical structure and can be difficult to navigate if levels are excessive.

This structure may be ideal for a site organized in groups of separate pages.

In any case, the number of levels should not be excessive, never more than 3.

List Structure

There is no home page; what we have is a sort of list of pages...

Understanding Websites and HTML

A website is a document written in HTML (HyperText Markup Language). It is a system that allows us to format text using tags. A web page can be composed of images, sounds, videos, and animations. HTML is a language focused on the transmission of documents using the HTTP protocol.

A website is a collection of pages linked together. These are viewed through programs called browsers, which interpret the tags added to the text, such as:

• Mozilla Firefox
• Google Chrome
• Opera

HTML uses two types of labels: opening (<tag>) and closing (</tag>). A website consists of a header and a body. Common tags include:

• Header: <h1>
• Paragraph: <p>
• Bold: <b>
• Italic: <i>
• Underlined: <u>
• Horizontal Line:

The scanner is a computer input device that allows you to scan images or documents using Optical Character Recognition (OCR). It emits light onto the document being scanned and captures the reflected light using a photosensor.

Types of Software

• OCR (Optical Character Recognition): Software specializing in extracting text characters from scanned document images, converting them into editable text.
• OMR (Optical Mark Recognition): Software designed to extract marks from documents, storing them as database fields.

Transmission of Photographs

• Wired: Traditional cable connections.
• Card Reader: For transferring data from memory cards.
• Infrared: Transmits and receives waves in the infrared spectrum. Requires devices to be side-by-side for communication (2-

What is DNS?

DNS (Domain Name System) is a service responsible for translating IP addresses into domain names and vice versa. It follows a client-server architecture and consists of a massive distributed database managed by specialized software.

Hierarchical Structure of DNS

• Root DNS Server: There are 13 super-servers scattered globally that work in unison. They contain the master tables for name resolution, though most operational work is delegated to other servers.
• Top-Level Domains (TLD): Maintained by internet authorities, these resolve top-level domain names.
• Second-Level Domains: These resolve second-level domain names and are maintained by domain owners or Internet Service Providers (ISPs).
• Subdomains: Added to the left of the domain name,

Spreadsheet Software and Advantages

Spreadsheet: Infomat is a program dedicated to operations from data arranged in tablas. Ventajas: we can store and retrieve operations later. If we entered data incorrectly, we can modify it without repeating the whole process, and it allows us simulaciones. Además, it can also be used in creating databases, graphics and documents that integrate text, images, results of operations, etc. Las spreadsheets used most include Galco, Gnumeric, Lotus 1-2-3 (IBM) and Microsoft Excel. They disponen of tools and a common work environment because many tasks are similar regardless of the type and application you're using.

Elements of a Spreadsheet

Elements spreadsheet: Table: It is an element that is used to store and...

Common Types of Computer Software

Microsoft Office and Productivity Tools

Microsoft Office makes office work easier. These are programs such as word processors, spreadsheets, or Personal Digital Assistants (PDAs). Example: Excel.

Design and Production Software

Design software is useful in the development of projects. These are used in technical drawing software, graphic design, computer simulation, and programming tools to facilitate various tasks. Example: Photoshop.

Programs in production are used for controlling machines and plants. Example: Mastercam.

Scientific and Communication Programs

Scientific programs are used for research in various fields such as meteorology and the simulation of natural processes. Example: Derive.

Communication programs...