Snapshots of doc/architecture

Hi,

I am currently working on two versions of Asterisk, the 1.4.21.2 (with zaptel) and the 1.8.25.0 (with dadhi). Could someone advise me where I could find some doc for development purpose (architecture diagrams etc) for those two versions, some snapshots for example ? The doc I see currently is only with dadhi and it has maybe been updated compared with the versions I use.

regards