Information about BIOS and the boot process

[Ivan Gustavo]

I am writing some code to fixup the video chipset trident 
cyberblade and V1621 RGB->CS encoder ,
and also trying to fix the IDE_BOOT for my mainboard (B860T or EPIA), so 
I am looking for information
about the real bios process, and about the layout of the common bios 
files, and of course, any information
about bios as possible.

My main problem is to find good documentation about the post, the boot 
process.

I read on some places which the CS is set F000 and EIP FFF0, so 
in other websites I had seen CS is FFF0,
 in other 000F , causing some confusion with me.

I need some documentation about 20bits addressing lines, and the GATE 
A20 function also.

Tanks in advance.