Device for processing telephone signals, including a processor and a preprocessor sharing a common memory

An apparatus for handling incoming signals from sensors monitoring the state of certain points of a telephone circuit as well as outgoing signals for drivers associated with other circuit points includes a preprocessor PE inserted between the assembly DR of sensors and drivers, on the one hand, and a processor EL, on the other hand. The preprocessor and the processor have access, through a bus 5, to a common memory ME having areas allocated to the scanning of the circuit points, to time-counting operations and to the storage of messages from the preprocessor. A microprogram memory in the preprocessor, when addressed by a sequencer CM started automatically, manually or in response to an instruction from the processor, initiates a temporary seizure of the bus-if the latter is available-whereupon an initial address is delivered from the common memory ME to a working memory ML in the preprocessor to start the scanning of successive pairs of circuit points. If the pair being scanned is connected to sensors, a change of state in either point is reported to the processor if verified by an integration procedure under the control of a read-only memory MIN in the preprocessor; if the points are connected to drivers, the same read-only memory MIN controls the emission of outgoing signals to them. Upon the completion of the scanning operation, the preprocessor performs lower-priority tasks of generating clock messages and measuring signal durations before relinquishing control of the bus.