1) why do you buy components in an antique shop? a small CPLD could handle all ( ale latch, ,memory decodeing, memory mapped I/O) in one Modern package.

Your problem, obviously, is a decodeing failure, write a snippet that put the P2 signals on P2 and use a scope to debug your decoder.

One other possibility, I have seen somewhere is that a signal after decodein came out with the wrong polarity (inverted).

Btw only decode the address select, do not decode the !RD and !WR.

Erik