Abstract: A telecommunication switching system including a plurality of terminal circuits each associated with a common control device. The common control device is coupled to a switching network through two interface circuits which operate asynchronously. The control device includes a processor and control means to successively allocate the processor to each of the terminal interface circuits. This uniquely simple solution requires only one control device while providing the high reliability that may be achieved through the use of two interface circuits.

Abstract: A telecommunication switching system includes a number of control circuits each of which is common to a plurality of line circuits and is coupled through time division multiplex links with two processor controlled interface circuits which are further coupled to a switching network. Line scanning information is processed in the control circuits to reduce the work load of the processor controlled interface circuits. Said line scanning information is then transmitted in the TDM links to the processor controlled interface circuits. The transmission priority among the control circuits is determined by a priority arrangement established for the system. A channel assignment controls the allocation of channels of the TDM links leading to parts of the line circuits.