A configuration and control unit (CACU) is described for a multi-system containing processors, which may be of different types, with heterogeneous channels and local and remote devices, including channel crossbar switches, I/O channel switches, I/O control units and I/O units. The CACU is the focal point in the multi-system for configuration, maintenance and special control over the multi-system.
The CACU contains a PWL adapter to control local devices, and a time multiplexed (TM) adapter to control remote devices. Time multiplexed lines (TML's) connect the TM adapter to remote modem adapters (RM's) located with remote devices. Each RM includes a configuration register, control register and maintenance register. These registers are connected between a modem in the RM and its associated device. These registers are operated by CACU commands to store the connection path between the remote device and any processor, communicate the connection path to the CACU on CACU command, provide special control for the device on command, and receive maintenance status from the device for communication to the CACU on command. Normal data to or from a remote device from a processor may pass through its RM adapter or may have a separate data path. Persistent storage devices are optionally providable in the RM for persistently storing the configuration signals currently in the configuration register. Upon failure of any item in the stored configuration path, the settings in the persistent storage devices can recover the connecton path for the remotely controlled device in the multi-system.