Notes, summaries, assignments, exams, and problems for Computer science

Fractions and Their Classifications

A fraction is a ratio of two integers.

Classification

• Proper: The numerator is smaller than the denominator, representing a number less than 1.
• Improper: The numerator is larger than the denominator, representing a number greater than 1.
• Apparent: The multiple of the denominator and numerator represents an integer.
• Mixed Numbers: These have a whole number part and a fractional part. They arise from improper fractions. To convert an improper fraction to a mixed number, divide the numerator by the denominator. The quotient is the whole number, the remainder is the new numerator, and the denominator stays the same.

Decimal Expression

A decimal expression is the result of dividing the numerator by the denominator of...

Process Management and Execution

Process: A program in execution.

Thread (Strand): The point of execution within a process.

States of a Process

Processes can exist in the following states: Running, Ready (standby or active), or Blocked.

Process Transitions

• Transition A: Running this program requires some element or signal to continue to run.
• Transition B: The program has used the CPU time allocated for its implementation and must make way for the next process.
• Transition C: This preparation process enters the implementation (execution) phase.
• Transition D: A blocked process transitions to the ready state.

CPU Scheduling Algorithms

• Round-Robin (Wheel Algorithm): Assigns relative execution times for different processes.
• FCFS Algorithm: Resources are allocated

Classification of Computer Memory by Function

Core Memory Components

• Central Memory: The portion of the CPU where instructions and data necessary for a given process are stored.
• Cache Memory: Stores frequently used instructions and data, significantly improving computer performance.
• Conventional Extended Memory: Accessed via specific software that forces the microprocessor into protected mode, or by utilizing 386/486 capabilities to allocate expanded memory as conventional memory.
• Conventional Expanded Memory: Memory inaccessible to standard MS-DOS programs. It requires an Expanded Memory Manager (EMM) to allocate pages of bytes as needed. Only EMS-compatible software can utilize this.

Primary Memory Types

• RAM (Random Access Memory): Classified by

1) Entering Configuration Screen

To enter the configuration screen from runtime mode:

• It depends on the configuration of the last application downloaded.

2) Dip Switch Settings

According to the dip switch settings shown in the figure:

• Starting from the CF card is disabled, you can download, and forced closure is disabled.

3) Screen Ventilation

To facilitate the ventilation of the screen, the manufacturer recommends a minimum distance of 100mm from any adjoining structure or equipment.

4) XBT-G LED Indicator

If the LED on the right side of the XBT-G screen lights orange, this means:

• Backlight is off.

5) COM1 Connector (SUB D25)

The female SUB D25 connector, COM1, of the XBT-G screen is used for:

• Serial communication with the PLC.

6) XBT-G Back Protection

The

C++ Staff Management System: Inheritance and Polymorphism

This document presents a refactored C++ program demonstrating object-oriented principles such as inheritance and polymorphism. The system models a basic staff management application, featuring a base Officer class and derived classes for specific roles like JusticeOfficer and Firefighter. It highlights dynamic memory management, virtual functions, and runtime polymorphism.

Core Concepts Illustrated

• Inheritance: JusticeOfficer and Firefighter inherit from the base Officer class.
• Polymorphism: Virtual functions (insert(), show(), destructor) allow for different behaviors based on the actual object type at runtime.
• Dynamic Memory: Usage of new and delete[] for character arrays (DNI, names) and

Fundamentals of Information Security

Core Security Principles

• Confidentiality (Privacy): Ensures information is not accessible to unauthorized individuals.
• Integrity: Guarantees information can only be modified by authorized personnel.
• Availability (Operability): Ensures information is accessible and usable when needed.

Common Information Security Threats

Software and System Vulnerabilities

• Bug: An error or flaw in a computer program or system that causes it to produce an incorrect or unexpected result, or to behave in unintended ways.
• Trojan: A type of malware that disguises itself as legitimate software, allowing external users unauthorized access to a computer system.

Network and Data Attacks

• IP Spoofing: The act of creating Internet Protocol (IP)

1. Scope of Multimedia

The term multimedia applies to both software and hardware. Programs are used for creating and editing sound, images, graphics, videos, and multimedia content in general.

2. Multimedia Software

Multimedia software is capable of handling and processing visual information.

3. Digital Sound

Digital sound is a sequence of binary numbers stored in a computer or device (e.g., MP3), created through a sampling process of analog sound or vibration.

• Sampling: The process of capturing and digitizing an analog sound.

4. Sound Quality Factors

The quality of a sound depends on the sampling rate and resolution (bit rate).

• Sampling Frequency: The number of samples taken per second (e.g., 44,100 samples per second).
• Bit Rate (Resolution): The number

Computer Software and Operating Systems

Software, the basic program that governs the operation of a computer, is the operating system installed on the hard disk of computers. Computers have a number of complementary programs, known as utilities, which are intended to keep the computer in an optimal functional state. They are part of software applications, all those programs whose mission is to facilitate the user in performing a task.

Satellite Positioning Systems

Positioning Systems: Satellite positioning systems are a new type of application of digital technology in telecommunications. These are systems of satellites in stationary orbit over the Earth, which emit signals in a coordinated way. These signals incorporate highly accurate information...

Relational Model: This approach allows users to obtain information from the database without assistance from information management professionals. The data is stored in a way that makes it easier for users to understand. The data is organized as tables, and the relationships between the rows and tables are visible in the data.

Features of Relational Models
It is important to know that the entries in the table are atomic. All entries in any column are of a single type. The table columns are called attributes. No two rows in the table are identical.

Structure of Relational Databases
The relational database model, at the conceptual level, is represented by a collection of stored relations.

Submodel Data
External schemas of relational sub-models are...

Performance Criteria for Data Transfer

Performance criteria are the most complex and critical factors to be analyzed before a transfer of data to achieve more effective performance. When determining the choice of route, you can choose based on:

• A path with the least number of hops.
• A path involving the least cost.

Instant Decisions and Routing Placement

The routing decision is made based on a packet or virtual circuit. When a routing decision is based on a datagram, it is taken individually for each packet. In the case of virtual circuits, internally governed packets belonging to that circuit will follow the same route.

A third case is Source Routing, in which the source station is the decision maker rather than the network nodes.

Node Responsibility