When you said you checked the CS, Did you check it relative to the generation of nIOW and nIOR?
- Yes, the nCS is gerated using the signals of nIOW or nIOR and the high pins of P2(7..4)


Also you didn't mention how you are latching the address lines.
- The adress lines of FDC is direct in 80c31 pins P2.1(A0), P2.2(A1) and P2.3(A2). And data is P1.