Abstract: A data receiver which includes a timing recovery circuit or periodically adjusting a timing signal used to control sampling of the received signal is arranged to reduce or eliminate phase jitter introduced as a result of the adjustments. Apparatus and a method are described for forming a correction factor which is a joint function of the timing adjustment increment and a previous correction factor. Typically, correction is accomplished by forming the complex product of the in-phase and quadrature-phase components of the received signal and the recursively updated correction factor.

Abstract: A device for screening unwanted telephone calls is connectable at a station etween a telephone set and a wall outlet plug. In response to ringing current received at the station and signaling an incoming call, the device delays audible ringing at the station for a 2.5 second period. During such period, the call's sender transmits to the station a # dial signal only if the call is in a special category as, say one undertaken to try to make a sale. If such # signal is received during such period, the device transmits back to the sender a return signal acknowledging that the call has been received and rejected at the station, and the device then hangs up call at the station without any audible ringing taking place there. If no such # signal is so received, audible ringing occurs at the line upon expiration of such period, and the call continues in its normal sequence.

Abstract: In accordance with the present invention, local loop testing in an echo canceller based modem is provided in a manner in which proper operation of both the receiver and echo canceller can be assessed simultaneously. Specifically, the modem includes means for generating data and interfering symbol sequences and for applying the interfering sequence to both the echo canceller and the modem transmitter, while applying the data sequence only to either the transmitter or the echo canceller. During closed loop testing, the modem connection to the transmission line is opened, and a portion of the output of the modem transmitter is applied to the modem receiver via a leakage path through the hybrid. The received symbol is subtracted from the echo canceller output, resulting in application to the receiver of only a version of the data symbol sequence. Advanced knowledge of the characteristics of the data symbol sequence allows proper receiver operation to be verified.

Abstract: Electro-static discharge is a problem with high-speed data even when using coaxial cables. Primarily, this problem arises at the terminal ends of the circuit where connections are made using separate coaxial cables for connecting to various pieces of equipment thereby allowing voltages to be induced differently in each such cable. This problem can be overcome by combining a portion of each cable such that the shield around each signal carrying wire remains intact while also being solidly in contact with the shield from the other wire. The cable is constructed by removing the outer insulation from a section of two single coaxial cables, electrically connecting together the exposed shields of each cable at both ends of the exposed section and reinsulating the abutted cables so that the shields remain in contact along their entire length.

Abstract: A system is disclosed for completing communication connections from end-users served by a connectionless (broadcast) type system in a manner which allows expansion of the calling area beyond the immediate physical limitations of the broadcast media. The system is based upon a device for mediating between the connectionless system and a connection oriented system. The device creates logical local area networks interconnectable by the connection oriented system. Calling user identification is used in conjunction with call completion data stored in a central memory for controlling all interconnections.

Abstract: An I/O interface (24) couples a plurality of I/O devices (29) to a main memory (22) by way of a system bus (23). The I/O interface includes a plurality of buffer blocks (110) permanently associated with one or more memory pages (240). Each page is contiguous within the memory address spectrum and includes a plurality of memory blocks (230). Under control of a sequencer (125), the buffer blocks temporarily store data items being transferred between the memory and the devices. Data items being transferred between any and all devices and a particular memory page are temporarily stored by that page's associated buffer block and no other buffer block. The sequencer accumulates in a buffer block a plurality of data items being transferred by a device to memory by successive write requests, and causes a direct memory access (DMA) conveyance of the buffer contents to the memory upon occurrence of any one of a number of events.

Abstract: An easily assembled connecting block provides interconnection between modular plugs and insulated telephone wires or the like. The connecting block includes: (i) a metallic lead frame comprising a number of flat elongated conductive elements that terminate in closely spaced flat wires at one end thereof, (ii) an equal number of metallic connectors that electrically couple to the conductive elements of the lead frame and further provide at least two pairs of opposing contact fingers for insulation displacement; and (iii) a dielectric block for receiving the closely spaced wires within a jack housing contained therein and for supporting the metallic lead frame. In one embodiment the connectors are an integral part of the lead frame itself and are "sandwiched" between a pair of dielectric blocks, each block having a plurality of corresponding slots for guiding wires into the region between opposing contact fingers of the connectors.

Abstract: A data processing system includes a processor unit (CPU) connected over a CPU bus to a plurality of memory components, but is not connected to any input-output (I/O) component of the system. The system I/O component(s) connect to the memories over an I/O bus. A method and apparatus is disclosed for selecting one of the memories to be used for communications between the processor unit and the I/O components. Also, a method for determining which I/O components are in the system.

Abstract: A portable data carrier system provides improved security for files which support multiple applications, from custom repertory dialing to storage of individual medical and/or banking records. Included in the system is a portable data carrier which looks and feels much like an ordinary credit card. The portable data carrier, however, includes a computer and an electrically erasable field programmable read-only memory. Power for operation of the portable data carrier is provided from an associated station via a reader/writer. The reader/writer also couples data between the data carrier and the associated station. Operation of the data carrier is through an executive operating system that is accessed from the station via a set of commonly understood command primitives. These command primitives manipulate the files in the data carrier in accordance with security requirements.

Abstract: A file system for a portable data carrier provides improved security for files which support multiple applications, from custom repertory dialing to storage of individual medical and/or banking records. Although the portable data carrier looks and feels much like an ordinary credit card, it includes a computer and an electrically erasable programmable read-only memory. Power for operation of the portable data carrier is provided from an associated station via a reader/writer. The reader/writer also couples data between the data carrier and the associated station. The applications reside in multiple files in memory on the portable data carrier. Appropriate application software residing in the station, when accompanied by an appropriate password, enables the retrieval and modification of these files. A separate password is required for gaining access to each of designated levels of interaction between the portable data carrier and the associated station.

Abstract: A resilient and deformable touch screen that is adapted to be overlaid on the surface of a CRT screen is formed from a semi-rigid plastic frame attached to a flexible plastic pouch filled with a soft resilient material which adheres to the surface of the pouch.

Abstract: There is disclosed a call announcement circuit arranged for connection to a communication system via a voice (or data) path and also via a separate control channel. Using this arrangement, the system main processor can control the message delivery capacity of the announcement circuit since the circuit has direct access to the internal system buses. This configuration allows detailed control of the announcement circuit on channels separate from the communication channel.

Abstract: In a data receiver employing a fractionally spaced equalizer, the phase with which samples of the received signal are formed is controlled in response to a signal indicative of the center of gravity of the equalizer coefficient.

Abstract: An arrangement is disclosed for delivering DC power (battery), voice, and ta signals from a telephone controller to a telephone station over first and second wire-pairs. Minimum interference between these signals is achieved when the first wire-pair is used as the voice signal path and the second wire-pair is used as the data signal path. DC power is fed out of the controller and into the center tap of an audio transformer interconnected with the first wire-pair. Ground current is returned to the controller through a balanced resistive circuit interconnected with the second wire-pair.

Abstract: In a multiprocessor system (FIG. 1), memory (22) of each adjunct processor (11-12) comprises global memory (42) and local memory (41). All global memory is managed by a process manager (30) of host processor (10). Each processor's local memory is managed by its operating system kernel (31). Local memory comprises uncommitted memory (45) not allocated to any process and committed memory (46) allocated to processes. The process manager assigns processes to processors and satisfies their initial memory requirements through global memory allocations. Each kernel satisfies processes' dynamic memory allocation requests from uncommitted memory, and deallocated to uncommitted memory both memory that is dynamically requested to be deallocated and memory of terminating processes. Each processor's kernel and the process manager cooperate to transfer memory between global memory and uncommitted memory to keep the amount of uncommitted memory within a predetermined range.

Abstract: A time division communication system having peripheral devices controlled om a port circuit is arranged such that the port circuit may have assigned to it a variable number of time slots for any peripheral device associated therewith. Each port circuit has a microprocessor control device which is capable of controlling communication to or from the port circuit over the system time division bus or to and from the port circuit and the peripheral over a variable number of time slots, none of which are preassigned to the port circuit.

Abstract: A pager arranged for operation in a cellular radio system provides economy to subscribers and technological flexibility to a system operator. Paging service is available in any geographical area covered by the advanced mobile phone service system. Subscribers are thereby able to travel at will while continuing to receive page signals in the cellular system. A special set of geographically dispersed channels in the advanced mobile phone service system are dedicated nation-wide to signaling and call control functions. These channels are used by the pager to properly configure itself to receive a page signal. The pager scans these channels, tunes to the channel with the best received signal strength and synchronizes with a received data stream on this or a second best channel. The pager then awaits receipt of the page signal. The pager also automatically rescans the special channels periodically to insure that it is always tuned to the channel with the best received signal strength.