The tutorial is about SAMD21 which is M0+ with VTOR. Simple bootloaders often do...

mmoskal on Sept 30, 2020 | parent | context | favorite | on: From zero to main(): How to write a bootloader fro...

The tutorial is about SAMD21 which is M0+ with VTOR. Simple bootloaders often don't need interrupts so on M0 one can get away with placing the bootloader at the end of flash and only rewriting the reset vector to lead to bootloader. Regular interrupts are then handled without any delays.