Abstract: A synchronous read channel is disclosed which samples an analog read signal from a magnetic read head positioned over a magnetic disk medium, filters the sample values according to a desired partial response, extracts timing information from the filtered sample values, and detects an estimated data sequence from the filtered sample values using a trellis type sequence detector matched to the partial response. The trellis sequence detector comprises programmable detector levels which allows for maximum flexibility in matching the sequence detector to the partial response.

Abstract: A synchronous read channel having a single chip integrated circuit digital portion which provides digital gain control, timing recovery, equalization, digital peak detection, sequence detection, RLL(1,7) encoding and decoding, error-tolerant synchronization and channel quality measurement is disclosed. The integrated circuit accommodates both center sampling and side sampling, and has a high degree of programmability of various pulse shaping and recovery parameters and the ability to provide decoded data using sequence detection or digital peak detection. These characteristics, together with the error-tolerant sync mark detection and the ability to recover data when the sync mark is obliterated, allow a wide variety of retry and recovery strategies to maximize the possibility of data recovery.

Abstract: A telephone answering system for providing textual messages and voice messages generated by telephone answering of telephones of persons having telephone calls answered by the system. A system memory stores textual and voice messages. A voice message recording system controls recording of voice messages of answered telephone calls of persons having telephone calls answered by the telephone answering system. A textual message recording system controls recording of textual messages provided by an operator who answers telephone calls made to persons having their telephones answered by the telephone answering system. A programmed computer program implements the voice message recording system and the textual message recording system by execution of a program.

Abstract: A synchronous read channel having a single chip integrated circuit digital portion which provides digital gain control, timing recovery, equalization, digital peak detection, sequence detection, RLL(1,7) encoding and decoding, error-tolerant synchronization and channel quality measurement is disclosed. The integrated circuit accommodates both center sampling and side sampling, and has a high degree of programmability of various pulse shaping and recovery parameters and the ability to provide decoded data using sequence detection or digital peak detection. These characteristics, together with the error-tolerant sync mark detection and the ability to recover data when the sync mark is obliterated, allow a wide variety of retry and recovery strategies to maximize the possibility of data recovery.

Abstract: A digital switching system connecting buses with incompatible protocols and a telephone answering system and private automatic branch exchange with integrated voice and textual message recording is disclosed. The digital switching system (10) in accordance with the invention permits a digital switching matrix (12) having an input bus and an output bus to connect information on the input bus selectively to information on the output bus in response to control signals applied to switches of the switching matrix. A plurality of information systems (18, 20 and 22) each having a different bus protocol are electrically connected to the input and output buses of the switching matrix to permit information transmitted on a conductor of any of the information buses to be received by another conductor of any of the information buses through the input bus, the switching matrix and the output bus. A host processor controls the plurality of information systems.

Abstract: A general-purpose, single-pass, adaptive, and lossless data compression invention implements an LZ1-like method using a hash-based architecture. It is suitable for use in data storage and data communications applications. Implementation efficiency, in terms of required memory and logic gates relative to the typical compression ratio achieved, is highly optimized. An easy-to-implement and quick-to-verify hash function is used. Differential copy lengths may be used to reduce the number of bits required to encode the copy-length field within copy tokens. That is, if multiple matches to a sequence of input bytes are found in the current window, then the length of the copy may be encoded as the difference between the lengths of the longest and the second-longest match, which results in a smaller copy length which likely has a shorter encoded representation.

Abstract: A digital switching system (10) in accordance with the invention includes a digital switching matrix (12) having an input bus and output bus; a plurality of information systems (18, 20 and 22) with each information system having an information bus for transmitting and receiving information using a protocol which is different from a protocol used by the information bus of each of the other information systems with the information buses of the information systems being electrically connected to the input and output buses of the matrix to permit information transmitted on any of the information buses to be received by any of the information buses through the input bus, the switching matrix and the output bus; a host processor (34), for controlling the information systems with commands; and a control processor (16), for generating control signals controlling switching of switches of the digital switching matrix.

Abstract: A Viterbi detector is modified to reduce its implementation complexity. A partial-response signal may be viewed as a sequence of expected samples generated from a finite-state-machine model. In a typical Viterbi demodulator implemented using the add, compare, select (ACS) method, each state in the expected sample sequence model is associated with a hardware module to perform the functions of adding new branch error metrics to path error metrics, comparing path error metrics, and selecting the path having the lowest path error metric. In this invention, an ACS module may have two or more sequence-model states dynamically associated with it, such that at some times one sequence-model state is associated with it and at other times another sequence-model state is associated with it. This reduces the number of ACS modules required and also reduces the size/complexity of the demodulator's path memories which must store one path for each ACS module.

Abstract: A telephone answering system for providing textual messages and voice messages generated by telephone answering of telephones of persons having telephone calls answered by the system. A system memory stores textual and voice messages. A voice message recording system controls recording of voice messages of answered telephone calls of persons having telephone calls answered by the telephone answering system. A textual message recording system controls recording of textual messages provided by an operator who answers telephone calls made to persons having their telephones answered by the telephone answering system. A programmed computer program implements the voice message recording system and the textual message recording system by execution of a program.

Abstract: A telephone answering system for providing textual messages and voice messages generated by telephone answering of telephones of persons having telephone calls answered by the system. A system memory stores textual and voice messages. A voice message recording system controls recording of voice messages of answered telephone calls of persons having telephone calls answered by the telephone answering system. A textual message recording system controls recording of textual messages provided by an operator who answers telephone calls made to persons having their telephones answered by the telephone answering system. A programmed computer program implements the voice message recording system and the textual message recording system by execution of a program.

Abstract: A telephone answering system for providing textual messages and voice messages generated by telephone answering of telephones of persons having telephone calls answered by the system. A system memory stores textural and voice messages. A voice message recording system controls recording of voice messages of answered telephone calls of persons having telephone calls answered by the telephone answering system. A textual message recording system controls recording of textual messages provided by an operator who answers telephone calls made to persons having their telephones answered by the telephone answering system. A programmed computer program implements the voice message recording system and the textual message recording system by execution of a program.