without any address "aliases" for the three wise latches, the needed decoder does not look very friendly, you know..., the need for including A1 in the decoder and the proable extra gates needed to do that ...all the stuff does not yield to an elegant design, on the other hand, all the circuitry needed to provide the /CS for an 8255 placed on 0xfffc..0xffff is a 74hc30 plus one single NOR gate. If you have time, design the decoder circuit for yourself, maybe you can present a better decoder who knows.

If you replace the "single NOR gate" with a '139, the chip count for the decode is the same.

Erik

PS, the design you mention make plenty of aliases 0xff10 alias with 0xff00 wtc