A high level overview. First separate it out in what the different processes are that are running in the working system. How are they communicating? What is th

A high level overview. First separate it out in what the different processes are that are running in the working system. How are they communicating? What is their function? Why was it separated in this particular way? For the more difficult of these programs/processes: what is their rough structure and what function does each part have? Why are they difficult? What strategies were used to conquer this difficulty? What are the most common ways in which they get extended? How does the build work?