For a very deep and specific dive, Fabien Sanglard has explained in detail Wolfenstein and Doom games technical implementation in his books Game Engine Black Bo

For a very deep and specific dive, Fabien Sanglard has explained in detail Wolfenstein and Doom games technical implementation in his books Game Engine Black Book: DOOM and Game Engine Black Book: Wolfenstein. The writing is from the point of view of reverse engineering and understanding why they were implemented as they were.