When you press the power b***on on your computer, you probably expect Windows, macOS, or Linux to spring into action. But here’s something most people don’t realize: by the time you see your desktop, your computer has already executed millions of instructions across multiple independent processors. It has already executed a large amount of firmware code across multiple controllers, potentially verified boot components with cryptographic signatures, trained memory, initialized devices, and prepared the machine to load an OS. And all before your actual operating system even begins to load.