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  • Paulo Almeida thinks this is interesting:

This initial program, or bootstrap program, tends to be simple. Typically, it is stored within the computer hardware in read-only memory (ROM) or electrically erasable programmable read-only memory (EEPROM), known by the general term firmware. It initializes all aspects of the system, from CPU registers to device controllers to memory contents.

From

Cover of Operating System Concepts, 9th Edition

Note

When you get a spare time, scrutinise this file: https://github.com/torvalds/linux/blob/master/init/main.c#L514