Supervisory control of peripheral subsystems

Abstract From the Canadian patent

A peripheral subsystem accepts and responds to a plurality of supervisory channel commands which alter the operation of the subsystem; i.e. logically partition, break the logical partition adjust or, amend the logical partition ignore the logical, partition, give operator controls for loading and unloading a record cartridge, suspending multipath reconnection and the like. These supervisory commands can be located anywhere in a I/0 chaining sequence. Some of the supervisory commands will result in changes in the subsystem operation for the duration of the instant channel program or CCW chain while other persist for as long as the subsystem is operating or until a subsequent supervisory …