Hi there. I know this is hard question, and possibly not to be answered here, but if there is some article, or more you know about, please post a link. About books, its sad but many great computer books cannot be bought in my country.

So, you can find many articles online, which says how memory was mapped back in pre x386 CPU. How there was explicit holes ready for MMIO BIOS, Video BIOS, etc. How there was A20 line for allowing higher memory access etc.

Problem is, time changed. Today BIOSes are many times larger, and pure x86 16bit mode is used for booting and ROM flashing only. OS ignore BIOS as they access everything using drivers. And I just want to know, how it works today. I know not so specific question, but I read OS dev wiki, many articles, but all refering to days before massive usage of pure 32bit CPUs.