I know that for a regular PC, BIOS executes its handler of interrupt
0x19 to search for a bootable device and if a device is found, first 512 bytes are loaded at 0x7c00 and BIOS starts execute from that address.
0x7c00, although are standard, are defined by BIOS manufacture.
Since microcontroller does not use external device like a hard drive to boot but use its flash memory, how do I know where is it going to load and execute bootloader code in flash memory? And using what interrupt? Is there any document, i.e. I have a TM4C123 microcontroller, what relevant documents do I need to look at to write a bootloader?