Operating System Fundamentals: Commands, Architecture, and Services

Operating System Concepts

1. Internal vs. External Commands

Internal commands are built into the command interpreter (like Command Prompt in Windows or Shell in UNIX) and are always loaded into memory when the operating system starts. They execute directly without requiring an external file and are faster. Examples in Windows include DIR, CLS, COPY, and DEL. In UNIX/Linux, examples are CD, PWD, ECHO, and EXIT.

External commands are separate executable files stored in the operating system. They are

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Core Concepts in Computer Graphics and Virtual Reality

Understanding Pixels, Resolution, and Back-Face Detection

A pixel (short for picture element) is the smallest unit of a digital image or display screen. It represents a single point in a raster image and has a specific color and intensity.

Resolution refers to the number of pixels in an image or display, usually written as width × height (e.g., 1920×1080). Higher resolution means more pixels, which leads to sharper and more detailed images.

Back-Face Detection Algorithm

Back-face detection is a hidden

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Essential Computer Science Concepts and IT Definitions

System Fundamentals

A system is a set of interrelated parts working together to achieve a common goal.

System Components

  • Environment
  • Inputs
  • Process
  • Outputs

Information Systems

An Information System (IS) is a set of elements and procedures designed to improve data processing and elaborate reports, facilitating decision-making to achieve beneficial goals.

Data Processing

Data Processing is a series of elementary operations performed on data to produce results.

Process Flow: Reception → Storage → Processing

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Operating System Fundamentals: Core Concepts & Components

Understanding Operating Systems

An operating system acts as an intermediary between a user of a computer and the computer hardware.

Scheduling Challenges

Scheduling involves managing machine time. For example, a user might sign up for an hour but finish their job in 45 minutes. This would result in wasted computer idle time. Conversely, a user might run into the problem of not finishing their job in the allotted time.

Operating System Types

  1. Serial Processing
  2. Batch Processing
  3. Multitasking or Time-Sharing
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Understanding File System Structure and Operations

File System Structure

A file system structure typically consists of:

  • Boot Block: Contains boot information.
  • Super Block: Contains metadata about the file system.
  • Inode Table: Contains inode structures for each file.
  • Data Blocks: Store file data.
  • Directory Blocks: Store directory information.

Key Components

  • Inodes: Contain file metadata (ownership, permissions, location).
  • File Descriptors: Identify open files.
  • Directory Entries: Map file names to inodes.

File System Operations

  • Create: Create a new file or directory.
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Core Computer Concepts: Hardware, Software, Networking

Understanding Computers and Data

Computers are machines capable of processing information and performing many different operations. They come in various forms:

  • Types of Computers:
    • Personal Computers (PCs)
    • Notebooks (Laptops)
    • Servers
    • Personal Digital Assistants (PDAs)

Data Measurement Units: Bits & Bytes

These units are used to measure the amount of information a device can hold.

  • Bit: The minimum unit of information. It’s a binary digit (0 or 1).
  • Byte: A fundamental unit consisting of 8 bits.
  • Kilobyte (
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