I tried to interface a 8255 PPI to a 80c320 µc.

I use it in Mode 0 (the simpliest) and i've a lot of problem with it :

By default, it was initialised as input, and a can read the input pins state.

But when i try to configure all io's as output (writting 0x80 in the control word reg), i cannot change the pins state ???

Furthermore, when i read the control reg. i don't read the previouly written value ???

Someone can help me ??