Bootloader

In computing a bootloader is a piece of code that handles part of the bootstrapping sequence of a computer. In PCs it is loaded by the BIOS, after it has completed it's portion of the booting tasks. It is this code that loads the operating system into memory and executes it. Some examples of OSes that are loaded with bootloaders are: Windows, Unix, Linux or MacOS.

The most common primary bootloaders today are:-


 * NTLDR (Windows)
 * FreeBSD boot0 (FreeBSD)
 * Chameleon (MacOS)
 * Grub (Linux)

However, often these small pieces of code do not provide enough of a code-set to launch a full operating system from, so this is where secondary bootloaders come in. Once this secondary Bootloader has been executed, there is enough commands to execute the first stages of the operating system, that can then load its own drivers before loading program files.