I have discovered some issues with the PCB designs I have had manufactured, and part of the issue is a lack of consistency. Take bus access, for example. The register card has placement for soldered wires or DIP switches to connect the register to the data or address bus. This is a bit limiting, but works and greatly reduces complexity. The memory card is even less complex, with the data pins linked to the data bus and the address pins linked to the address bus. When it comes to the counters, I want more flexibility to use them on either bus and as transfer registers between the buses. If the ALU can write to either bus, it can act as a partial transfer register... but it will need to be able to read from either bus for this to be useful.