12. A data compression method for compressing a stream of data characters into a stream of compressed codes, comprising storing strings of data characters in storage means, each said string having a code associated therewith, searching said stream of data characters by comparing said stream to said stored strings to perform a character-by-character match therewith until the longest match between said stream of data characters and said stored strings is determined, outputting the code associated with said longest match so as to provide said stream of compressed codes, entering extended strings into said storage means, the entry of said extended strings being interleaved with the matching of the data characters of said character-by-character match, said extended strings comprising the previous longest matched string corresponding to the last outputted code extended by each data character, in turn, as each data character is matched during said character-by-character match, one of said extended strings being entered for each said data character matched and before a next data character is matched during said character-by-character match, the entering of said extended strings during said character-by-character match continuing until said longest match is determined, and assigning respective codes to said extended strings.
12. A data compression method for compressing a stream of data characters into a stream of compressed codes, comprising storing strings of data characters in storage means, each said string having a code associated therewith, searching said stream of data characters by comparing said stream to said stored strings to perform a character-by-character match therewith until the longest match between said stream of data characters and said stored strings is determined, outputting the code associated with said longest match so as to provide said stream of compressed codes, entering extended strings into said storage means, the entry of said extended strings being interleaved with the matching of the data characters of said character-by-character match, said extended strings comprising the previous longest matched string corresponding to the last outputted code extended by each data character, in turn, as each data character is matched during said character-by-character match, one of said extended strings being entered for each said data character matched and before a next data character is matched during said character-by-character match, the entering of said extended strings during said character-by-character match continuing until said longest match is determined, and assigning respective codes to said extended strings. 17. The method of claim 12 further including outputting a data character encountered for the first time in uncompressed form following an indication that such a data character is being output, and entering said data character encountered for the first time into said storage means as a single character string.