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

Processor Front

The processor front involves three components: source, destination, and message. The source (e.g., a terminal or computer) sends a message. The destination (e.g., another terminal or computer) receives the message. The front-end processor acts as the connection between the source and destination, managing the message transfer. It frees the host processor from communication tasks, handling message routing, transmission monitoring, code translation, and encryption. All data transmitted to or from the host processor are managed through this specialized front-end processor, allowing the host processor to operate more efficiently and focus on application processing.

Types of Communications

A network enables computer connections to share... Continue reading "Computer Network Communications" »

Software Development Models

Attributes of Effective Requirements (AtrERS): Correct, unambiguous, complete, verifiable, consistent, modifiable, concise, organized, searchable, understandable by the client, regardless of design.

Scaling Factors: Correctness, reliability, efficiency, integrity, ease of use and maintenance, flexibility, ease of testing, portability, reusability, ease of interoperation.

Life History: Succession of stages through which a software product passes during its existence. Attempts to determine the order of the steps involved and the criteria associated with the transition between these stages.

Software Engineering: Application of scientific knowledge to the design and construction of computer programs and associated documentation... Continue reading "Software Development Models: Waterfall, Prototype, and More" »

Advanced Features

Advanced features facilitate consultation similar to a spreadsheet because they work based on rows and columns.

• COUNT(): Count the number of rows in the column set
• MIN(): Find the minimum value of the column set
• MAX(): Find the maximum value of the column set
• AVG(): Gets the average values in the column set
• SUM(): Gets the total value implied by the values obtained in the column provided

Modifying the Database

SQL DDL has modules for the definition of data that allows us to create or modify table structure.

The instructions for these operations are:

• CREATE TABLE: Allows you to create an empty data table.
• INSERT: Allows you to store records in a table created.
• UPDATE: You can modify data records stored in the table.
• DELETE: Deletes a record

Network Topologies

Ring Topology

Connects hosts in a physical ring. The last host connects to the first.

Star Topology

Connects all cables to a central point.

Extended Star Topology

Connects individual stars using hubs or switches, extending network coverage.

Hierarchical Topology

Similar to extended star, but uses a computer to control traffic instead of hubs/switches.

Mesh Topology

Provides maximum protection by connecting each host to others, ensuring service continuity.

Network Communication Methods

Broadcast

Each host sends data to all others on the network. Access is first-come, first-served (e.g., Ethernet).

Transmission Tokens

Controls access via sequential token transmission. Hosts send data when they have the token (e.g., Token Ring, FDDI).

Network

AI Meets AI: Leveraging Query Executions to Improve Index Recommendations

How artificial intelligence (AI) can benefit automated indexing (AI)?: Comparing the execution cost of two plans (different index configurations of same query) is key for index tuning. Instead of using optimizer’s estimates for such comparison, formulating it as a classification task in machine learning results in significantly higher accuracy.

MOTIVATION:

• Being able to fully automate index recommendation and implementation is a significant value-add for improving query execution cost.
• Requirement: creating or dropping indexes should not cause significant query performance regressions - users enforce a no query regression constraint.
• Using the optimizer’s estimates to

Microprocessors

The microprocessor is the device responsible for processing the data received. It is able to perform arithmetic operations and transfer blocks of information. The increase in processing power allows for faster and faster PCs. This is mainly due to improvements in architecture, microcode, and operating speeds.

Overclocking

Overclocking is a method used to obtain faster processing speed by increasing the domestic multiplier value of the microprocessor. It is not advisable because it causes overheating of the processor. Besides the increased frequency, it may result in errors of "timing" and then produce erroneous results or hang the system. You can also overclock the system clock speed, which will affect the overall team bus. This... Continue reading "Microprocessors and Memory Types: A Deep Dive" »

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

Operating System (OS)

Software that manages hardware resources and provides a high-level abstraction for the user.

Process

A program currently executing.

Multitasking System

An OS allowing multiple programs to run concurrently.

Multiuser System

An OS allowing simultaneous access for multiple users.

Command Interpreter (Shell)

A user interface program that executes commands.

System Calls

Interfaces (APIs) used by programs to request services from the OS.

Single-Tasking System

Allows only one job in memory at a time. The CPU is idle during I/O operations, as it cannot be used by another process when the current one accesses system resources.

Time-Sharing System

Allows multiple terminals connected to a central computer. Enables multiple processes to use the... Continue reading "Operating System Core Concepts" »

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