I found a treasure on eBay this year and I shared it on Archive.org (link above, scroll down below the image) and Minuszerodegrees (Manuals > Third parties > Compaq).

It is a Compaq internal document of 1986, a full technical documentation of the first commercially available 80386 PC.

It is of interest for historical reasons (read abstract on Archive.org) and for people who would like to re-create a free x86-32 hardware respecting the original design... Something like a PC NuXT upgraded to 80386 or better.