I'm back from my little vacation in Vegas and have been busy building.  I bought a sheet of 1/4" acrylic to mount all the boards together.  I was tired of trying to clip them together with wires or headers.  It's working nicely.  I wanted to start running all my control lines into their positions so I can get rid of all those big loopy wires.  I couldn't do that until I had a place for them all to go (the empty board at the bottom).  I have room for another column of breadboards on the left side of the data bus.

I finished the RAM / ROM module and tested it.  I used a ZIF socket for the 32K ROM chip to make reprogramming quick.  I have more of them for the microcode ROM's.   The address bus is removed in the picture as well as the data bus connections to the RAM ROM module.  The RAM / ROM module is technically "external" to the CPU and my DI control line would be the R/W output.  The DI control line would control the tri-state buffers between the internal and external data bus.