After some apprenticeship with this project, I started a new one with the same goals that this has, but now with a little more knowledge and aprimoring some things like: "What did I use to think that is the best idea to build it stackable??", or "Why to map all 16 I/O pins to the bus?" and "why do not use commom address to the commom I/O devicecs like VDP board on 0x30h? Really?" and dome other stuff. Because of that bunch of things and some others, I started a new one thats looks more promessing and is the one that I will focus from now on. I would like if you can take a quicly look on that: https://hackaday.io/project/195954-the-homebrew-handwired-z80-computer-h2z80