Zugvogel

What I undersand from you PM is:
We are talking about S88 Bus.

I don't know this bus,
but what I read from your short description it can't be much of a problem to solve this in PBP.

- What type of PIC are you using?
- What type of shift registers are you using?
- How many "Feedback" lines are there?

Could you post a schematic?