[Etherboot-developers] references for booting a PC

[<in...@ca...>]

I would like to have a better understanding of the booting process of a PC. I
have read the developper manual of etherboot and learned quite a bit, notably
from the section "The execution environment of Etherboot". I have also read the
source code and learned even more, notably from floppyload.S and start16.S.
However, there is still much I do not understand about booting a PC. For
example, I still don't quite understand why it's necessary to relocate to the
top of the memory, just below the 4Gb limit.

My question is: are there any books, online references or manufacturer
specifications I could read in order to have a better understanding of booting a PC?

My suggestion is: other people might find the answer to the above question
useful, so perhaps a reference section could be added to the developper manual.