It is much better to put the 8255 (if you have to use it) in the uppermost adresses. You can be lazy and just use A15 and maybe an inverter for decoding, but then you just get 32K usable 28C512. If you use some more adress bits and maybe an x-input andgate you will get more usable part of memory. Your 8255 will get mirrored in many adresses in the area, it may be acceptable.