This document must contain many wrong, misunderstood information because of lack of knowledge of the author. When you find them, please kindly notify me. Author assumes no responsibility to the contents of this document. MBR has the first stage loader. Memory Map first.
S contains information about memory map as a comment.
Contents Offset Size Offset in first. So, control starts at 1st stage loader code. 1st stage loader must fit into single sector size in MBR, and can't do much job by itself. It simply loads 2nd stage loader from certain location of disk into memory. Here is the flow of control.