There is another comment explaining it; in short, "boots first and has low level control of the SoC". Defining "main processor" is certainly arguable, as there

There is another comment explaining it; in short, "boots first and has low level control of the SoC". Defining "main processor" is certainly arguable, as there isn't a unique way of viewing the architecture, but on the other hand, the idea that ARM boards are "very custom" still stands. Some informations: - https://raspberrypi.stackexchange.com/questions/10489/how-does-raspberry-pi-boot https://raspberrypi.stackexchange.com/questions/10489/how-do... - https://raspberrypi.stackexchange.com/questions/14862/why-does-the-raspberry-pis-gpu-control-the-first-stages-of-the-boot-process https://raspberrypi.stackexchange.com/questions/14862/why-do...