Electronic switching system

Claim 1

In a stored program controlled electronic telephone switching system, a processor system comprising in combination; duplicated central control units operating in synchronism and including means for matching the information processed by each of said central control units; duplicated data channel devices, each of said data channel devices comprising a channel multiplexer and a sub-channel equipment constructed to accomodate input-output units and other devices including a signal unit for a common channel signalling system and a data link line terminal unit of a digital trunk, under a common interface condition whenever such device is required; a plurality of non-duplicated main memory devices accessible to any one of the above units or devices; means for selectively coupling said data channel devices and central control units to said main memory devices; a pair of peripheral memory devices operating in asynchronized mode and connected to each one of the duplicated data channel devices; means for transferring information between the main memory devices and the peripheral devices via respective data channel devices; means for periodically copying a part of the memory contents of the main memory devices alternately into respective ones of the peripheral memory devices to thereby duplicate the information to be processed, copied information from said peripheral memory devices being read out by transfering the copied information back into the main memory devices; means for causing one central control unit and the part of the main memory devices to operate independently of the ever central control unit and another part of the main memory devices, said one central control unit and said part of the main memory devices forming one processing system, while the other central control unit and another part of the main memory devices forming another processing system.