There are three major functional groups on this board:
- A self-initializing 8-bit shift register that produces the one-hot CPU phase of execution signals (A12, A22, A32, M12, M22, X12, X22, X32) and the SYNC signal.
- The 5-bit Chip Select decoder and external output drivers (CMROM, CMRAM0 to CMRAM3). This is the chunk of logic that I moved off the ALU board.
- The 4-bit, tri-state, bi-directional data bus external pin I/O drivers.
I expect the parts I've already placed will shift position (and possibly rotate in the case of the Chip Select logic) to accommodate the data I/O drivers but I don't expect any problems making it all fit. This board has the fewest components of any board in the set and there's quite a bit of free space left.