Ben Eater has an amazing tutorial about building a very simple 8 bit computer. It only has 16 bytes of memory. I thought that I could build a 16 bit computer with 64K of addresses, have a combination of Flash, RAM, and Registers. This page will have the details.
Here is where the rubber meets the road. I'm starting to think I don't need the X register. It was the register that the Controller needed to handle 16 address or constants. So far in writting the micro-code for the instructions, I've not needed it. I don't think I will need it for the moves, sinc e I can move things from Ram to the register that it goes to in one step. I may make it register E.