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Understanding Firmware and Boot Process

Apr 22, 2025

Firmware and Boot Process

Overview

  • Firmware: A small program stored in a chip on the motherboard.
  • Initial program run by a computer to start the boot process.

Functions of Firmware

  1. Initialize Hardware Devices
    • Checks if all hardware devices are functional (Power On Self Test - POST).
    • Halts startup if any hardware is not functional.
  2. Find Bootloader Program
    • Bootloader can be stored on storage devices like hard disks, USB drives, CDs, or DVDs.
    • Firmware specifies boot device priority (boot order).
  3. Execute Bootloader Program
    • Controls the remaining boot process.

Types of Firmware

  • BIOS
    • Released in 1975; operates in 16-bit mode.
    • Basic UI; keyboard navigation; supports up to 14 partitions.
    • Takes longer boot time; supports password protection.
    • Uses MBR (first 512 bytes of a device).
  • UEFI (Unified Extensible Firmware Interface)
    • Released in 2002; operates in 32-bit and 64-bit modes.
    • Graphical UI; faster boot times; supports secure boot.
    • Supports up to 128 partitions; uses GPT (after first 512 bytes).

Bootloader and Partition Storage

  • MBR (Master Boot Record)
    • Classical method; reserved first 512 bytes.
    • Non-redundant; maximum of 14 partitions.
  • GPT (GUID Partition Table)
    • Modern method; uses 4 KB after 512 bytes.
    • Redundant; supports up to 128 partitions.

Partition Types

  • Standard Partitions
    • Used in personal computers; easy to manage.
    • MBR supports primary, extended, and logical partitions.
      • Max 4 primary, extended holds logical partitions.
    • GPT has a flat scheme; supports sequential partition creation.
  • Advanced Partitions
    • Used in server systems; may require additional tools.
    • LVM (Logical Volume Management)
      • Creates logical pools from standard partitions; flexible resizing.
    • RAID (Redundant Array of Independent Disks)
      • Stores data on multiple disks for backup.

File Systems

  • Organizes sectors and indexes files.
  • Determines file names, attributes, metadata.
  • Common file systems: NTFS, ext4, XFS.

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