Ahh. Since the driver sets up what each bank means and handles the switching you should be able to pull that data by other means. You may end up not even using a core bank then.
Ggghhhh. Have you seen
sms_mapper_w? It reads like stereo instructions. That's kind of lame that whatever it is that SMH_BANK does can't be manually invoked.
That said, I think I have a lead, so... yeah.
Edit: Heck with it. I can't, for the life of me, figure out what it wants. Someone else can hook up the 93C46. It doesn't help that Meka's source code is harder to read than Greek.