Exchange with program controlled central control - has main control unit and reserve unit which has access to data channels only when active

摘要

The exchange control units are duplicated, one of them controlling the exchange and the other standing by in reserve. Stores are common and can be reached from both control units. At any time actively operating control units have access to a common data channel through monitoring devices (KE) permanently allocated to the duplicated control units. The stand-by units have access to the data channel, to which the non-duplicated stores are connected, only during pauses in the active units operation. The stores and also a monitoring device are connected to the data channel in the same way as the duplicated input/output interfaces.