Channel programs for activating the MPC connection

A series of channel programs is issued when the operator activates the MPC connection. These I/O exchanges are used by the hosts to communicate various capabilities to the other host. The capabilities are transferred using the XID channel program.

The primary pieces of new information gained through the MPC XID exchange are:
  • MPC to CTC connection
  • Polarity of the device (Read or Write)
  • I/O buffering information for an active connection