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

Data Management Function in Extended MVC

The Data Management (DM) component provides the basic infrastructure for the storage and retrieval of objects within a system. Its primary purpose is to isolate the impacts of underlying data management technologies on the overall software architecture.

Specifying Data Management: Common Approaches

The most direct approach for this persistence layer is to provide a shadow class within the Data Management (DM) component for each persistent class in the other architectural components, such as the Problem Domain (PD) components. The standard DAO (Data Access Object) pattern is widely used for this task.

Essential Features for Data Management Construction

Three important features for constructing the Data Management... Continue reading "Data Persistence & Management in Extended MVC Architectures" »

Database Architecture

The definition of an information system is the detailed description of the system architecture.

Internal Level

The lowest level of abstraction, defining how data is stored on hardware and accessed. Responsibilities of the Database Administrator (DBA) include managing:

• Block size
• Relative position of stored records
• Addressing methods
• Overflows
• Indexing
• Storage changes
• Compression techniques

Conceptual Level

The mid-level of abstraction, representing the organization's data. This level encompasses partial views of different users' requirements and potential uses. It provides a total organizational vision, including data definitions and relationships. DBA responsibilities include:

• Defining the data stored in the database:
  • Data name
  • Attributes
  • Relationships

Core Computer Architecture Components

CPU Registers Explained

CPU registers are small, high-speed storage locations within the central processing unit (CPU) that hold data and instructions for immediate processing.

Accumulator Register

The Accumulator Register stores the results of executed operations. It connects to input registers for feedback in chained operations and also connects to the data bus for sending results to main memory or the control unit.

Program Counter (PC)

The Program Counter (PC) stores the memory address of the next instruction to be executed.

Instruction Register (IR)

The Instruction Register (IR) contains the instruction currently being executed.

Understanding Computer Buses

A bus is a channel or set of parallel connections that... Continue reading "Computer Architecture Fundamentals: CPU, Memory, Buses, and Addressing" »

Software Architecture Design Principles

Key aspects of software design include:

• Software Architecture Design: Defines the major structural components of the software and their relationships.
• Project Data Design: Involves designing the data structure needed to implement the software.
• Procedural Design: Refines and details the procedural description of the structural components defined in the software architecture.
• Interface Design: Describes how software communicates internally (internal interfaces), with other systems (external interfaces), and with users (user interface).

Component vs. Class Diagrams in UML

Similarities

• Both can realize a set of interfaces.
• Both can participate in various relationships (dependency, generalization, association).
• Both

Program Counter (PC) and Instruction Register (IR)

The Program Counter (PC) contains the address of the instruction to be read. The Instruction Register (IR) contains the last statement read.

Interrupts

Interrupts interrupt the normal execution of the processor. They appear mainly as a way to improve processing efficiency. Interrupts can be generated by software, clock, I/O, or hardware failure.

Disabled Interrupts

Disabled interrupts mean that the processor will ignore the interrupt signal. If an interruption occurs during that time, it generally will remain pending and will be checked by the processor after it enables interrupts.

Processor Actions

When the processor interprets the instruction and performs the action, the action can be classified... Continue reading "CPU Operations: Interrupts, I/O, DMA, and Multiprogramming" »

Computer System Components and Definitions

Perform = realizar || Word processor = procesador de textos || Built-in = incorporado || Store = tienda || Financial = financiero

Keep, save = mantener, guardar || Execute, do = ejecutar, hacer || Monetary = monetario || Connected to the internet = conectado a internet || Program used for text manipulation = programa para manipular texto || Copy files from a server to your PC or mobile = copiar archivos de un servidor a PC o móvil

Perform operations = realizar operaciones || Do research = hacer la investigación || Carry out transactions = llevar a cabo transacciones

Monitor = monitor || Keyboard = teclado || Printer = impresora || Scanner = escáner || Speakers = altavoces || Fan = ventilador || Processor

Fundamental Number Concepts

Prime Numbers Up to 97

Here is a list of prime numbers up to 97:

• 2
• 3
• 5
• 7
• 11
• 13
• 17
• 19
• 23
• 29
• 31
• 37
• 41
• 43
• 47
• 53
• 59
• 61
• 67
• 71
• 73
• 79
• 83
• 89
• 97

Rules for Exponents

Understanding how exponents work is crucial for various mathematical operations:

• Positive Base: If the base (m) is positive, the result (b) of mn = b is always positive.
• Negative Base, Even Exponent: If the base (-M) is negative and the exponent (n) is an even number, the result (+b) of (-M)n = +b is positive.
• Negative Base, Odd Exponent: If the base (-M) is negative and the exponent (n) is an odd number, the result (-b) of (-M)n = -b is negative.

Powers of Decimal Numbers

Here are examples of squaring and cubing decimal numbers:

• 1.12 = 1.21
• 0.42 = 0.16
• 0.032 = 0.0009
• 0.23 = 0.008

Divisibility Criteria

Divisibility... Continue reading "Essential Number Properties and Divisibility Rules" »

Programming Language Fundamentals

Level Classification

• Low Level: Resembles the language used by the computer directly.
• High Level: Resembles human language, abstracting machine details.

Generations of Programming Languages

• 1st Generation (1GL): Machine Language
• 2nd Generation (2GL): Assembler
• 3rd Generation (3GL): High-level languages (e.g., Fortran, Pascal, C, C++, Cobol)
• 4th Generation (4GL): Languages for specific purposes (e.g., web development, PHP, Java, HTML)

Key Programming Concepts

Program

A set of instructions or orders based on a programming language that a computer interprets to solve a problem or perform a specific function.

Programming Language

Tools that allow us to create programs and software. An artificial language used to define a sequence... Continue reading "Programming Language Basics & Database Models" »

Semaphores: Synchronization Tool

Semaphores are a synchronization tool designed to solve critical section and synchronization problems. A semaphore is an integer variable accessed only through two atomic operations: Wait and Signal. When a process modifies the semaphore's value, no other process can simultaneously modify that same semaphore value. The semaphore is initialized to a non-negative value.

Wait and Signal Operations

• Wait (P): Decrements the semaphore's value. If the value becomes negative, the process is blocked.
• Signal (V): Increments the semaphore's value. If the value is not positive, a blocked process waiting on this semaphore is unblocked.

The definitions are:

P(s):

while (s <= 0)
s--;

V(s):

s++;

Operating System Usage

Operating... Continue reading "Semaphores for Synchronization in Operating Systems" »