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What is a Boot Loader & it's components?

By Sai Rohith Karanam

To understand what is a boot loader, it is recommended to see my previous post-Basics of Booting.
Here is the link if you haven't seen it yet-
https://sairohithkaranam.blogspot.com/2020/05/what-is-booting.html

      What is a Boot Loader?
  1. The boot loader is the small program stored in ROM that loads the kernel from a storage device and then starts the OS.
  2. A boot environment like BIOS/UEFI reads the boot loader from ROM so that boot loader can execute various operations to start the process.
  3. Boot loaders are able to protect the boot process with a password to prevent unauthorized booting of the system.
  4. In addition, boot loaders can load more than one OS into the computer's memory.
Now that you've understood about booting and boot loader, let's learn about the components of a boot loader.

       Components of a Boot Loader:
       The boot loader uses three main components that load the operating system together.
  1. Boot Sector Program:
    →The first component of the boot loader.
    →It is loaded by a boot environment on startup and has a fixed size of 512 bytes.
    →Its main function is to load the second stage boot loader.
    →However, it can load another sector or kernel.
  2. Second Stage Boot Loader:
    →Loads the operating system and contains a kernel loader.
  3. Boot Loader installer:
    →This controls the installation of drive sectors and can be run only when booting from a drive.
    →It coordinates the activities of the boot sector program and second stage boot loader.

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