GB1406165A - Data exchange systems - Google Patents

Abstract

1406165 Data transmission systems SIEMENS AG 10 April 1973 [9 May 1972] 17104/73 Heading H4P In a data exchange system including a switching matrix at the cross points of which are switching elements U 11 ... U 1m .. .U n1 ... U nm a holding store HS1 ... HS n is provided for each row (or each column) and, when a crosspoint connection between a row and a column is required, the binary coded address of the particular crosspoint is recorded in the store assigned to the particular row (or column), the output from each store being connected to a respective decoder DK1 ...DK n , the outputs of which are connected individually to control inputs of the switching elements at the crosspoints of the row (or column) to which the store is assigned. If a call is received on an input line, Z 1 say, a control circuit ST searches for a free output line, S, say, and writes its address in store HS1. Decoder DK1 then provides an output which enables F.E.T. AND gate U1 so that data from input Z1 will pass via AND gate U11 and OR gate O1 to output S1. The addresses of operative switches may be stored in marker stores MS1 ... MSm assigned to the columns if the holding stores are assigned to the rows, or vice versa. If subsequently a particular connection is disestablished, the relevant switching element may then be left switched through. When required for another connection, the address stored in the marker store provides an instruction to erase the previously stored address in the holding store. Alternatively the holding stores may be checked by a comparator which erases the contents of the holding store which are identical with the address of the new connection. The holding stores are connected to the rows or columns, whichever are lower in number.