How are you generating the 3 address lines and nCS, nIOW, and nIOR?
- nIOW and nIOR are generated direct by 80c31 nWR(p3.6) and nRD(P3.7).
But nCS is gerated using the ICs 74hc139, 74hc00 and 74hc14 , to dph = C0h . We have already tested the generation of the nCS signal. It seems it is working well.

Are you using interrupts and IRQ or DRQ/nDACK/TC?
- No. the nDACK pin is conected to Vcc, DRQ and TC are not conected.