Notes, abstracts, papers, exams and problems of Computers

Object Identity Types

There are three main types of object identity:

• Asset (Data Value as Identity): This form of identity, commonly used in relational systems, utilizes a data value as the identifier. For instance, the primary key value in a tuple uniquely identifies that tuple.
• Name (User-Defined Identity): This type of identity relies on a name assigned by the user. File systems often employ this approach, where each file has a unique name regardless of its content.
• Incorporated (System-Generated Identity): This concept integrates identity directly into the data model or programming language, eliminating the need for user-provided identifiers. Object-oriented systems commonly use this method, automatically assigning a unique identifier to each

Gantt Chart: A Project Planning and Control Method

A Gantt chart is a graphical method of planning and control in which a project is divided into different activities, and estimates are made about how long each activity takes. This chart shows the timing relationships between events of a program and was developed by Henry L. Gantt. Gantt charts are useful for monitoring relatively small projects.

Understanding Key Concepts

• Task: Project activities are carried out in a particular sequence.
  • Predecessor Task: A task that must start or finish before another can begin.
  • Successor Task: A task that depends on the start or finish of a preceding task.
  • Summary Tasks: These are made up of subtasks and summarize those subtasks.
• Milestones: A task without duration

Creating Engaging Multimedia Presentations

A presentation is a multimedia file that can contain text, graphics, photos, music, and video. Its organization is done by slides, which succeed one another under your control. Templates are presentations that have predefined design objects in the slides, such as the background, fonts, placement of text, and other objects that give the presentation a common appearance across all slides.

Interactivity: Establishing Hyperlinks

Interactivity is established by creating hyperlinks. Clicking on a button or text performs an action, such as opening a file or linking to a website. You can insert a hyperlink from the Insert menu, then selecting Hyperlink.

Interactivity in objects allows navigation to different slides... Continue reading "Creating Engaging Multimedia Presentations" »

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... Continue reading "Computer Science Fundamentals and Programming Basics" »

Parbegin / Person Learns

Parbegin is a structure to indicate parallel execution, marking the beginning and end. Selection: A statement dividing sequential execution into parallel streams.

Its general form (Dijkstra):

parbegin Proposition1; Proposition2; Proposition n; person learns

Mutex

Mutex occurs when processes share data, preventing simultaneous access. It applies when a process accesses shared data, allowing concurrent execution of non-conflicting transactions.

Critical Sections

A process accessing shared data is in a critical section. When a process is in a critical section:

• All other processes are excluded from their critical sections.
• Other processes can execute outside their critical sections.
• When a process exits, the next waiting process

Database Queries

Queries are objects in a database that allow you to filter data in a table or query. They display data from a table that meet specified criteria.

Selection Queries

Selection Queries extract or show only the data that you specify. The results can be used to modify the data.

Action Queries

Action Queries make changes to records in a single operation. Types include delete, update, append, and create tables.

Creating a Selection Query

To create a select query, follow these steps:

1. Open the database where you want to create the query.
2. Click the Query object to the right of the database window.
3. Click the New button in the database window.
4. Select Design View.
5. Click the OK button.
6. Select the table to query.
7. Click the Add button.
8. For queries from multiple

Runtime Memory Organization

The organization of memory at runtime depends on the type of language (declarative, imperative), the compiler, and the operating system.

General Structure of Programming Languages

When you run a program, the OS loader allocates the required amount of memory and loads the code to be executed (stored in a file) into the code area.

The OS should detect collisions between the stack and the heap. In these cases, the program may abort, or the amount of allocated memory may be increased.

In memory paging systems, the above scheme can be fragmented and scattered between real memory and the virtual memory system.

Any reference to a storage location within the code should be relative to the position assigned to the process by the... Continue reading "Runtime Memory Organization: Code, Static Memory" »

1. Expansion Cards

Utility

Expansion cards add new features or improve existing ones in a computer. They facilitate communication between internal and external peripheral devices and the system bus.

Disk Controller Card

Disk controller cards, once used to manage hard disks, CD-ROMs, DVDs, and floppy drives, are now integrated into the motherboard.

Video Card

The video card is crucial for displaying text, images, and graphics on the monitor.

Components

• Video Processor: Receives, processes, and stores information in video memory, transmitting it to the monitor via the VGA connector.
• Memory Chips: Hold information needed to display pixels on the screen.
• AGP: Allows the card to be inserted into the AGP slot.
• Port for the Monitor: Connects the card to the