Abstract: Processing system for interpreting and carrying out a set of logically related instructions stored into a software program, the execution of a given instruction by the processing system involving the decoding and the execution of a corresponding set of microcommands. The processing system stores a signature portion corresponding to the macrocommand portion of a given instruction which is to be interpreted and executed, and signature data in response to the actual decoding and execution process of the microcommands involved in the execution of the instruction. The processing system further compares the computed signature data with the signature portion in order to detect the occurrence of an error in the decoding and execution process of the given instruction. In one embodiment of the invention, the processing system is such that one instruction is interpreted and executed in one elementary machine cycle.

Abstract: A communication controller CCP includes line adapters (104-i) each having a storage which is loaded with a general application program during an initialization phase. The line adapters allow the attachment and the communication of different telecommunication entities, e.g. a LAN, a teleprocessing line etc. . . The CCP is connected by means of a control adapter to a local control terminal (100) which is associated with a storage for storing the different general application programs which are likely to be required by the different line adapters. A storage contains an access key comprising data relative to the types and the number of line adapters of any type which are authorized to be loaded with the general application program stored in the storage controlled by the control terminal. The CCP also has logic for checking whether a loading request received from one adapter complies with the contents of the stored access key in order to prevent the loading of an unauthorized line adapter.

Abstract: A line interface circuit for connecting the transmit and receive ports of a transmitter to transmit lines (LX) and receive lines (LR), respectively. The interface circuit includes a transistorized differential amplifier provided with two load circuits comprising resistors and diodes connected in series, and logic control means for selectively switching power to either load circuit. One of the load circuits drives the transmit line (LX) while the other drives the receive ports of the transmitter. Switching the load circuits makes it possible to use the interface circuit either to drive the transmit line (LX) or to loop the output signal from the transmitter back to the receive input thereof, while loading the transmit line (LX) with its characteristic impedance.