Given that you have two devices that require some partial decoding, you can use A15 (P2.7) as the E strobe, for example, and A8 (P2.0) as the RS line, which selects between control and data. However, what you may have a problem making fit is the timing.

The RW line when using MMIO is normally the nWR signal from the 805x. That signal is valid for only a short time, even on a pretty slow 805x. IIRC, the nWR signal from the typical 805x 12-clocker operating at 11.05 MHz is short enough to cause many HD44780-interfaced LCD's to fail. That, sir, is the reason few people attempt to use MMIO with LCD's on 805x types. It's too bad, but the low-going write pulse does seem to be too short.

Before you expend too much time on this, you might want to examine the read and write strobe lengths with your oscilloscope. You may find it works better at a lower clock rate. You then have to change the setup for the serial port.

RE