If you happen to’ve ever experimented with a microprocessor on the naked steel stage, you’ll know that when it begins up, it’s going to take a look at its program reminiscence for one thing to do. On an previous 8-bit machine, that program reminiscence was normally an EPROM in the beginning of its handle area, whereas on a PC, it will be the BIOS or UEFI firmware. This takes care of initialising the surroundings in each {hardware} and software program, after which loading this system, OS, or regardless of the processor does. The Raspberry Pi, although, isn’t like that, and [Patrick McCanna] is right here to inform us why.
The Pi eschews mentioning its ARM core first. As a substitute, it has a GPU firmware that brings up the GPU. It’s this a part of the chip that then initialises all peripherals and reminiscence. Solely then does it activate the ARM a part of the chip. As he explains, it is because the unique Pi chip, the BCM2835, is a set-top-box chip. It’s not an utility processor in any respect, however a late-2000s GPU that occurred to have an ARM core on a small a part of its die, so the GPU wakes first, not the CPU. Regardless that the newest variations of the Pi have far more highly effective Broadcom chips, this legacy of their ancestor stays. For many of us utilizing the board it doesn’t matter a lot, nevertheless it’s attention-grabbing to know.
Fancy making an attempt naked steel Pi programming? Give it a go. We’ve seen some sensible tasks that begin at that stage.
