o/p & i/p PIO

Hi all,

I have 2 cascaded processors, one has an o/p PIO and the other has an i/p PIO. I want to know please the way of making the o/p PIO affects the i/p PIO to drive the 2nd processor into interrupt mode. I looked at "countbinary.c" to see how it's done but I am still lost.

Thanks in advance