On both 8051 and 80251 the external data bus was only 8 bit.

So you need to combine 2 * 8 bits for write and split into 2 * 8 bits for read.

This can be done with a bidirectional latch, e.g. 74HC646.

To generate the control signals and for address decoding I would suggest a GAL16V8 or similiar.

I have never done such thing, thus I have no schematic available.


Peter