Thanks Melanie for your prompt reply.

You mean that i have to add a line between the PICs and (i.e.) rise it when a PIC is reading or writing on the bus ,so the other ( with input pins)must wait for the low line for accessing the bus ( the bus is free).Is it correct?

And sorry but due to my poor english i cant understand well this sentence:

"Everything else you can do in PBC or PBP."

Do you mean that it's all i can do with picbasic?

Thanks again
roberto