Abstract: The disclosed data compressor compresses an input stream of data characters using LZW data compression. When the occurrence of a run of input data characters is detected, the run is processed by successively looking ahead into the input to determine the contiguous numerically increasing segments that exist in the run and by utilizing codes from the compressor code counter to correspond to the contiguous numerically increasing run segments. Alternatively, the detected run is processed by determining the length of the run and mathematically determining, from the length of the run, the respective codes from the code counter corresponding to the contiguous numerically increasing segments that exist in the run. Specifically, an iterative mathematical algorithm or a quadratic equation algorithm are utilized to process the run.

Abstract: The disclosed data compressor compresses an input stream of data characters using LZW data compression. When the occurrence of a run of input data characters is detected, the run is processed by successively looking ahead into the input to determine the contiguous numerically increasing segments that exist in the run and by utilizing codes from the compressor code counter to correspond to the contiguous numerically increasing run segments. Alternatively, the detected run is processed by determining the length of the run and mathematically determining, from the length of the run, the respective codes from the code counter corresponding to the contiguous numerically increasing segments that exist in the run. Specifically an iterative mathematical algorithm or a quadratic equation algorithm are utilized to process the run.

Abstract: In an LZW data compressor, the occurrence of a character run in the input character stream is determined and the run count is added to the existing code in the compressor code counter to generate a compressor code output representative of the run count. The LZW data decompressor subtracts the existing code in the decompressor code counter from the received compressed code to recover the run count. In accordance with a further feature, large length runs are processed by reducing the run count to less than the system maximum code by subtracting a selected predetermined constant from the run count. The reduced run count is outputted by the compressor preceded by a reserved code representative of the selected predetermined constant. In response to the received reserved code and the reduced count that follows, the decompressor adds the selected predetermined constant corresponding to the received reserved code to the received reduced count to recover the original run count.

Abstract: The disclosed data compressor receives an input stream of data characters and provides a corresponding stream of output codes. The compressor generates a sequence of numerically increasing output codes corresponding to numerically increasing contiguous segments of a detected run of the same data character. Non-run characters of the input stream are transmitted directly in synchronism with incrementing the codes of the code sequence. In one embodiment, the number of characters in the run segments are stored together with the respective codes representing the segments. In later encounters of a previously processed run, the stored data is accessed and the stored codes corresponding to the run segments are output as appropriate.

Abstract: The disclosed data compressor receives an input stream of data characters and provides a corresponding stream of output codes. The compressor provides a sequence of numerically increasing output codes corresponding to numerically increasing contiguous segments of a detected run of the same character. The number of characters in the detected run is determined and a mathematical algorithm, using the number of characters in the run, mathematically generates the appropriate sequence of codes. One disclosed embodiment utilizes a mathematical algorithm that iteratively diminishes the number of run characters by an iteratively increasing segment index. Another embodiment utilizes a quadratic equation algorithm that computes the codes from the number of characters in the run utilizing equations derived from the expression for the sum of the first n numbers. In a further embodiment, the number of characters in the run segments are stored together with the respective codes representing the segments.

Abstract: A dictionary based data compression and decompression system where, in the compressor, when a partial string W and a character C are matched in the dictionary, a new string is entered into the dictionary with C as an extension character on the string PW where P is the string corresponding to the last output compressed code signal. An update string is entered into the compression dictionary for each input character that is read and matched. The updating is immediate and interleaved with the character-by-character matching of the current string. The update process continues until the longest match is found in the dictionary. The code of the longest matched string is output in a string matching cycle. If a single character or multi-character string "A" exists in the dictionary, the string AAA . . . A is encoded in two compressed code signals regardless of the string length. This encoding results in an unrecognized code signal at the decompressor.

Abstract: Using LZW data compression/decompression processing techniques, textual input data is compressed by parsing consecutive words of the text into phrases and storing the phrases in a dictionary with compressed phrase codes associated therewith. The textual input data is searched by determining the longest match with the stored phrases in the dictionary and the compressed phrase code associated with the longest match is output to a compressed text database and stored at a location thereof. A list of references is maintained associated with each stored phrase to the locations in the compressed text database at which the compressed phrase code for the phrase is stored. Lists of word-to-phrase references are also created providing references for each distinct word encountered in the text to the stored phrases containing the word.

Abstract: A dictionary based data compression and decompression system where, in the compressor, when a partial string W and a character C are matched in the dictionary, a new string is entered into the dictionary with C as an extension character on the string PW where P is the string corresponding to the last output compressed code signal. An update string is entered into the compression dictionary for each input character that is read and matched. The updating is immediate and interleaved with the character-by-character matching of the current string. The update process continues until the longest match is found in the dictionary. The code of the longest matched string is output in a string matching cycle. If a single character or multi-character string "A" exists in the dictionary, the string AAA . . . A is encoded in two compressed code signals regardless of the string length. This encoding results in an unrecognized code signal at the decompressor.

Abstract: An associative memory is utilized to perform LZW data compression. The respective locations of the memory contain a prefix code field and a character field. A register containing a code field and a character field is associatively compared to the locations of the memory to determine if a match exists therewith. If a match is found, the address of the match is inserted in the code field of the register and the next input character is inserted in the character field thereof. This process is continued until no match occurs. The code existing in the code field of the register is transmitted as the compressed code of the string and the contents of the register is written into the next empty location of the memory. A next cycle is initiated by nulling the code field of the register and repeating the described steps.

Abstract: An associative memory is utilized to perform LZW data compression. The respective locations of the memory contain a prefix code field and a character field. A register containing a code field and a character field is associatively compared to the locations of the memory to determine if a match exists therewith. If a match is found, the address of the match is inserted in the code field of the register and the next input character is inserted in the character field thereof. This process is continued until no match occurs. The code existing in the code field of the register is transmitted as the compressed code of the string and the contents of the register is written into the next empty location of the memory. A next cycle is initiated by nulling the code field of the register and repeating the described steps.

Abstract: A voice messaging service system for caller accepted voice store and forward service. The service offering prompt is issued during dial tone in response to caller off-hook, advising that the service can be accepted by the caller if the call to the intended recipient is not completed. Alternatively, the service offering prompt is delayed after caller off-hook for a time interval sufficient for the caller to dial the telephone number of the intended recipient. As a further embodiment, the service is offered for acceptance by the caller without advancing the call to the intended recipient.