G8PP board with processor in its prototype area works well with Z80 and I expect it to work just as well with other 40-pin or 48-pin CPU. However, the prospect of having to manually wire 40+ connections for every processor is unpleasant. A better configuration is having two boards plug into a backplane. Ideally, the G8PP should not be modified physically except the CPLD reprogrammed for different processors. The specific processor is a separate board that plugs into a backplane along with G8PP. The backplane also has additional slots for expansion. The picture below illustrates this concept.
The G8PP+CPU concept is now a two-board system: G8PP in baseline configuration consists of clock, RAM, CF interface, and CPLD. The CPLD can be reprogrammed in-situ to accommodate different processors. No additional manual connections are needed when change processors. The G8PP baseline becomes a pc board without myriad of jumper options. This is the schematic of the G8PP baseline
The CPU board is a simple pc board with pre-defined addresses, data, clock, power, and reset pin assignments same as RC2014, and few processor-specific control signals unique to the particular processor. The prototype CPU board in the picture is hand wired, but it can easily converted to a pc board. This is the schematic of the Z80 processor board.
The resulting 2-board system work just like the single-board version described in Part 2. All software that run in the single-board version also run in the two-board system.