As explained before the main hurdle in the process of making a S18 multi was to be able to reproduce the custom chip used in "newer" games to expand ROM size by using a banking mechanism.
Since the solution to that could have a big impact on the design I decided to take an intermediate step: I decided to design a small adapter board to host a CPLD that would plug in place of the original custom chip.
So this:
Was replaced like this:
Ok, ok, it barely fits, it's ugly but...
It works!
I chose Desert Breaker for the test because it's the biggest game (biggest main CPU ROM size/biggest sprite size/biggest tile size) requiring the highest address lines for each bus to be generated properly.
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