FWIW, I checked the Q605 ROM, and it just does one iteration over the banks, always leaving the value the same as what I used to make 128MB SIMMs work. Additionally, I realized for my mod, a full 260MB is being recognized, which means the builtin 4MB is still being seen with the same configuration value as the 128MB SIMMs. Now I'm really wondering why it ever was the original value.