¹ The reason for this asymmetric treatment of the links can be found in the way the links operate. If you look back to Figure 2-6, you will find that information going out of a transputer is accompanied by a status bit, so the receiver can "see" that there is information ready to be shifted in. For information going out, however, there is nothing coming from the receiver to indicate that it is ready to receive. So the ProcAlt function can only check the status bit associated with channels or link bringing information in, and not out