There were four rounds. The first was a general HR screening call with some basic questions like, "Why do you want to work at SpaceX?" If you are who you say you are, you'll pass this one. The second round is a 4-hour programming test with one question. It takes candidates about 2 hours to complete it. It has automated tests, and if you pass all the tests, then you'll likely move on to the next interview. The third round was a 45-minute call with the hiring manager that included a few basic conceptual questions and an in-depth dive into a technical project you've seen to completion. As long as you know what you're talking about and are passionate about it, you'll likely pass this one. The fourth round was an on-site interview. This consisted of an hour-long presentation given by me to the team, a tour of the factory, lunch on-site, and four one-on-one interviews. The one-on-one interviews ranged from conceptual questions to talking more about your presentation to a coding question.

Pretend I'm a non-engineer. Explain how something like an iPhone works from the basic building blocks all the way up through the memory organization and operating system interactions with the hardware. Be as specific as possible without using terms that non-computer engineers would not understand.