My address decode logic appears to be working (so far). I have a simple program running from flash ROM now.

Bank 0 RAM now running. I pulled the TXS0108E level shifter, as it wasn't pulling down the OE lines very well. I replaced it with discrete transistors (a couple for now, more to add). Also, I slightly reworked the OE and CS signals for the Flash ROM and RAM. Next: VIA and 4-line LCD output.