Hello! Here is simple diagram for booting flow of modern Intel laptops. Feel free to ask questions, request for improvements, giving hints. Why Intel? Just because it is more complex than modern AMD systems. Why laptop? Same reason - more complex than desktop. If you have an idea howto merge laptop and desktop booting in one diagram - please share. Attaching both png result and MS Visio 2010 source.
Best regards, Anton Kochkov.