Communication line status scan technique for a communications processing system

A communication processor is coupled to recognize and handle on a priority basis, service interrupt requests from a plurality of communication line adapters. The processor is also adapted to perform a firmware-controlled scan of the communication line adapters, completely independently of any data transfers involving such adapters, to determine the status of the communication lines handled thereby and, on detection of a status which is changed from a previously stored status, to store the new status in the processor and take any action necessary as indicated by a command previously stored in the processor.