Bootloaders serve as a mediator between hardware and the operating system. As soon as a bootloader has been initialized by the respective firmware, it has system responsibility to get the boot process going. The first task is to load the main memory, which is essential for the processor to work.
In the second step, the bootloader loads the kernel of the operating system, that is, the primary component of the system software that controls all storage and processor permissions and contains all important drivers. The bootstrap loader also processes different routine tasks and commands, e.g. integrating data storage. Some bootloaders also perform tasks beyond starting up software, including:
- Identifying and starting other available bootloaders
- Launching application programs (frequently used in the 1980s to launch computer games directly from a disk)
- Correcting or expanding missing functions and entries in the firmware
- Loading alternative firmware
After successfully completing all tasks, the bootloader returns the system responsibility to the kernel.