Abstract: Several forms of scanner are known: exception reporting, 3-cycle scanning with block exception reporting and response-mode reporting. Additionally positive-edge reporting is now required. The present invention enables the achievement of all these requirements within a rationalized scheme involving a considerably extended field size, and therefore, using a "last-look" 256 or 512 bit shift-register. This is employed in conjunction with a pre-programmed read-only memory, which stores for each different field-type served by the scanner a program relevant to that field. Each program address is formed by injecting the state of the scanned point as a least significant bit carry into an adder fed with (i) the N-1 most significant bits of the previous address in a sequence control register and (ii) an address increment value read from the location previously addressed while the current state of the last-look shift register is used as the least significant bit.

Abstract: A bi-directional switching network for a telecommunications exchange in the form of a matrix array of symmetrical switching devices each having many terminations at opposite sides. The switching devices of each row individually have their terminations at one side multipled whereas the switching devices of each column individually have their terminations at the other side multiplied. In a preferred embodiment each switching device includes at least one switching module comprising A-switches, B-switches and a C-switch all of the relay-matrix type; the first two categories of switches being arranged in planes. Connections are usually established over an A-switch and a B-switch of an appropriate plane, but the C-switch is available for interposing between any A-switch and B-switch under heavy traffic conditions and provides for switching between planes.