Mr Mudaliyar,

Here we go ...

1. A circuit working fine with 80c31 and 80c32.
2. Mudaliyar modifies circuit and changes chip select address of external chip (whatever it is.)
3. In new setup 80c32 alone works. 80c31 does not.

What needs to be known..

A. When you say 80c31 does not work, how much does it work if at all ? Runs upto some point and hangs / does not even start running / smokes / what ?

B. If you revert to your old setup then does 80c31 work ? If your answer is YES to this, then in all probability the new hardware setup is the problem and the 80c32 working on it is by sheer luck. ( Meaning it can stop working anytime..)

Raghu