Abstract: Improved ISDN interface apparatus and methods permit dual mode access to an on-board memory. A first memory controller is provided that responds to addresses in a first address range to read, write or otherwise access data in an “on-board” memory a first memory access mode. A second memory controller is provided that responds to addresses in a second address range to access data in that memory in a second memory access mode. Multiplexing circuitry selectively applies control signals from the first or second memory controllers to the memory, thereby, causing it to read, write or otherwise access data according to the first or second modes. The aforementioned first and second modes can constitute differing memory access modes. Thus, for example, first mode is a single-beat memory access mode, according to one practice of the invention. The second mode can comprise, on the other hand, for example, a burst mode.

Abstract: A method and apparatus for reducing the amount of corrupted data in a system for transmitting encoded data across a network, which system requires sychronization between encoding and decoding nodes, the method and apparatus involving (a) providing an indication of the reliability of the channel between the encoding and decoding nodes; (b) performing automatic resets at the nodes at intervals I; and (c) utilizing the indication of channel reliability to control the interval I. The interval I may be determined, for example, by the error rate on the channel for one or more preceding time interval S, and may be determined at either the encoding or decoding node.

Abstract: A single queue or descriptor ring references several context control blocks, each of which corresponds to a different data path in a communications system. An entry in the descriptor ring references an appropriate context control block and a source packet representing a packet locations prior to processing. The descriptor ring may include a destination packet representing the packet locations after processing. The descriptor ring is particularly suitable for communications between a main processor and a coprocessor.

Abstract: The invention performs very fast switching between a main module and a standby module in the event of module failure. A single control line has different logic level signals applied thereto in the event of a main module failure and a standby module failure, with the signals on the control line being utilized to efficiently switch the on-line status of the modules to a desired state.

Abstract: The invention provides a method and apparatus for controlling the timing at a receiving station for the receipt of asynchronous data transmitted with a time-stamp. The received data is passed through a buffer to the remainder of the station. A decoder at the receiving station generates an indication of buffer fill level and a local time-stamp is also generated. The output timing for the buffer is controlled by a circuit which is responsive to both a difference value off, received and locally generated time-stamps and to the fill level indication.

Abstract: A system for transmitting compressed data for multiple channels or contexts from a single node which system reduces memory utilization without significant adverse effect on compression ratio by providing a separate history buffer for each channel, with a single hash table being provided for generating potential match addresses in the history buffer for at least selected ones of the channels. A single chain table may also be provided, the chain table having a single offset address for the corresponding offset addresses in the buffers for the selected channels. Collisions in the common hash table may be reduced by including channel address or the like as an additional input to the hash table, thereby biasing the address outputs therefrom.

Abstract: A flexible backplane assembly is provided wherein removable backplane modules are mounted in a platform in a manner such that the backplane modules may be removed and replaced to accommodate different types of circuit modules. Coacting guides are provided on the platform and the backplane modules to define a travel path for module insertion and removal which prevents contact with adjacent circuit and backplane modules and maneuvers around platform structural members. Connectors at the rear of each backplane module for mating withy circuit module connectors may be electrically connected to I/O boards at the front of the module to permit wiring of the backplane modules from the front of the platform.

Abstract: A cable guide assembly for use with a panel which has a plurality of adjacent mounted circuit members, such as panel mounted telephone switching circuits, with a plurality of fiber optic or other cable whose performance would be impaired if bent beyond a minimum bend radius extending therefrom. The guide assembly manages the running of the cable toward either end of the panel from each circuit member in a manner such that the cable cannot be bent beyond its minimum bend radius. In particular, an effective curve surface is provided at each point where the cable changes direction, with the cable passing over such surface and such surface having a radius which is not less than the minimum bend radius of the cable.

Abstract: A pulse receiver for connection in a telephone circuit including two coils connected between a voltage potential and ground further including an external impedance that is alternately connected between the coils. The pulse receiver includes a first impedance connected in series with the first coil and a second impedance equivalent to the first impedance connected in series with the second coil and an input circuit connected across the first impedance for detecting the connection of the external impedance of the telephone circuit. Switching circuitry is provided that is connected to the input circuitry and alters a first output node pair from a normally closed state to an open state and alters a second output pair from a normally open state to a closed state in response to a signal received from the input circuitry indicative of the detection of the external impedance connection.

Abstract: An electronic switch for use in the tip and ring circuit of a rotary dial telephone pulsing system is disclosed. The electronic switch is a functional replacement for a single pole, double throw electromechanical pulsing relay having normally open and normally closed output terminals, with the state of the output terminals being reversed in response to the connection of an external impedance load to an input sensing node. Normally open and normally closed output nodes are driven by first and second output switching circuits. The operating states of the first and second output switching circuits are reversed in response to a switching signal generated by a binary switch. The binary switch is biased off with no switching signal being produced in the absence of the external impedance load so that one output terminal is normally open and the other output terminal is normally closed.