Notes, summaries, assignments, exams, and exercises for Computer science for Vocational training

Software Fundamentals

Software: Part of computer logic. All programs managed by the computer. A set of rules and instructions.

1. System Software (SW Base)

A set of programs that control the computer and form the base of application software. It allows the inner workings and facilitates user interaction and machine-to-machine communication.

1.1 Operating Systems (OS)

The closest layer to the machine, it acts as an intermediary between the user and the machine. It is the first program loaded into memory and is essential to operate the machine. Two types of interfaces exist: text and graphics.

Functions of an Operating System:

• Planning, supervision, and load initialization when running a program.
• Manage all system resources.
• Initiate and control I/O units

Understanding DNS: Domain Name System

DNS is the translation mechanism that converts domain names into IP addresses. A domain is the name that identifies a website. Common top-level domains include:

• .com: Commercial organizations
• .edu: Educational organizations
• .net: Internet-related organizations
• .org: Non-commercial organizations
• .gov: Government organizations

When to Use a DNS Server

A DNS server is necessary when maintaining the /etc/hosts file is no longer feasible due to the volume of entries.

What is DNS Delegation?

Delegation is a mechanism that allows for the decentralization of database administration by dividing DNS domains into subdomains.

Network Example

Consider a Class C network (192.168.100.0) with subnet numbering determined by a mask,...

Digital Counters (Sequential Circuits)

Counters are sequential circuits whose output represents the number of clock pulses applied to the input. They consist of interconnected bistables (flip-flops).

Counters can operate in ascending mode (content increases with each pulse) or descending mode (content decreases).

Applications of Digital Counters

• Watches and Timers
• Frequency Dividers
• Frequency Meters (Frecuencímetro)

The maximum number of states a counter passes through is called the Modulus.

Asynchronous (Ripple) Counters

In asynchronous counters, the external clock signal is connected only to the first flip-flop. The clock input of subsequent flip-flops is connected to the output of the previous flip-flop.

This configuration causes all flip-flops...

User Accounts: To use the Unix operating system you must have a user account that consists of user name (login) and password (password). User accounts are created by the administrator in Unix is a special user called root.
User Groups: All users belong to at least one group that is the main user group, also called user's primary group but can belong to more groups. If you belong to more groups, these are secondary groups.
Root: The root user, sometimes called root, is the user administrator. Is identified with the user number zero (uid = 0) and has permissions on the entire system without any restrictions. The root user can access any file, run, install and uninstall any application, modify the system configuration files and manage users.

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Wide Area Networks (WAN)

A Wide Area Network (WAN) spans a large geographic area, such as a country or continent. Its primary function is to connect networking and terminal equipment located at great distances. These networks rely on an infrastructure of powerful switching nodes to facilitate the continuous flow of significant amounts of information. WANs are considered public networks because they handle traffic from diverse locations, enabling users worldwide to transmit data across vast distances.

Network Protocols

A network protocol is a set of rules specifying the exchange of data or commands for communication between systems. These rules allow information to flow between computers that might otherwise handle different languages. If two computers...

Social Web and Web 2.0

Web 2.0 was born to complement existing online services. It is based on them and focuses on user contributions to the development network, providing, revising, or modifying content.

Key Web 2.0 Components

• Wiki: Websites edited by different people in a collaborative way.
• Blog (or Weblog): Websites that function like a personal diary where contrasting views are expressed, and content or discussions are moderated by the blogger.
• Photo Albums and Videos: Sites where users contribute their photos and videos.
• RSS (Really Simple Syndication): A web subscription service for news search and consultation. It allows access to news from digital newspapers or radio stations.
• Podcast: Retransmission of news or events in audio format that

Network Resource Sharing Fundamentals

A network resource is a logical entity capable of action at the request of another. The use of shared resources can be performed through a network.

High-Speed Data Connectivity

Disk Management and Fiber Channel

For servers, Fiber Channel interfaces are important for fast disk connections with extreme speed specifications.

Fiber Channel technology is traditionally used for building Storage Area Networks (SANs). The Fiber Channel Standard is an interconnection technology designed for broadband communication. This standard consists of a set of standards developed by ANSI.

• Maximum distance allowed: 10 km.
• Protocols transported include: SCSI, IP, IPI, HIPPI, IEEE 802, and even ATM.

Managing Printing Resources

Local Area...

Understanding Core Network Protocols and Services

Introduction to Network Fundamentals

• The Internet Control Message Protocol (ICMP) is an IP protocol used for sending control, reporting, and discovery messages.
• Network architectures are built upon dependent levels or layers.
• The complexity of a network directly impacts its reliability.
• Virtual communication is a fundamental aspect of modern media.
• End-to-end flow control is a critical network function.

Transport Layer Protocols: TCP and UDP

• An advantage of including the transport level is that protocols can be designed to conceal underlying network complexities from applications.
• The primary data unit at the transport layer is the Transport Protocol Data Unit (TPDU).
• Transport level protocols include

Essential Web and Software Terminology

Web Navigation and Structure

• External Hyperlink

  A hyperlink that opens a webpage located on a remote computer. External hyperlinks provide the links that tie the Web together and rely on HTML anchor tags.

• Back Button

  A basic control used across various technologies. In a web browser, a back button allows an end user to navigate to a previously viewed webpage. A back button is also a feature of smartphone software and other consumer-oriented technologies.

• Navigation Structure

  When using navigation requests, for each BSP application, determine the initial page, the navigation methods, and the target pages in a table with navigation paths.

• Refresh

  An act or function of updating the display on a screen.

Web Elements

Word Processing

• Word processing program: A computer utility that allows you to create, edit, and save documents.
• Format: A specific way in which a document is stored.
• Spell check: A program utility that corrects misspelled words.
• Template: A predesigned document with gaps to be filled in.
• Font: A specific style of typeface used for documents.
• Compatibility: The ability of a word processing program to open documents created by other software.
• Layout: The arrangement of text and images on a page.
• Macro: Frequently used sequences of commands or text.

Email

• Email client: A program that saves, sends, and receives emails.
• Domain name: Words or letters used to identify companies and addresses.
• Password: Letters or numbers that allow a person to access an account.