How to study the ao486 project?

Hi , I am a newer to FPGA, I major in computer architecture. Recently，I want use the FPGA to prove my some work(focus on pipeline ,especially in decoder), and  I find the amazing work - ao486 project. But I have no idea of how to study it, because It is so complex. Is anyone can give me some advise of how to study it. 
think you very much  