A brief look at the 3DS cartridge protocol

About a week ago, there has been a little addition to the 3dbrew wiki page about 3DS cartridges (carts) that outlines the technical details of how the 3DS cartridge controller and a 3DS cartridge talk to each other. I would like to take this opportunity to also include the 3DS itself in the conversation to illuminate which part of which device performs which step. I will then proceed to outline where I think the corresponding design decisions originate. Finally, I will conclude with some concrete ideas for improvement.
↫ Forbidden Tempura

Everything you ever wanted to know about 3DS cartridges and how they interact with the 3DS.