Data communication system for transmitting data in compressed form

Claim 2

Data communications apparatus comprising: A. first buffer means for providing a first plurality of data representative of the present data to be compressed; B. second buffer means for providing a second plurality of data representative of data previously compressed; C. means for comparing the individual data in said first buffer means with the individual data in said second buffer means; D. means, responsive to the comparison made by said means for comparing, for generating a new map indicating, in the order of comparison, the number of repeat data and the number of non-repeat data detected between said first and second pluralities of data; and E. means, responsive to said means for generating, for transmitting only those individual data of said first plurality of data which are detected to be non-repeat data as indicated by said new map.

Claim 3

Apparatus as in claim 1 further comprising: A. an old map which indicates the number of repeat data and the number of non-repeat data detected between two successive, previously compared pluralities of data; B. means for determining whether said old map is useable for transmitting those individual data of said first plurality of data which are detected to be non-repeat data; C. means, included in said means for transmitting, for using said old map for such transmission instead of said new map, if said old map is determined to be useable for transmitting those individual data of said first plurality of data which are detected to be non-repeat data; and D. means, included in said means for transmitting for additionally transmitting said new map if said old map is determined to not be so useable.

Claim 4

Apparatus as in claim 2 further comprising means for decompressing said data received in compressed form from said means for transmitting, said means for decompressing comprising: A. means for storing the last plurality of data received from said means for transmitting; and B. means for storing the last map received from said means for transmitting; and C. means for regenerating said data in decompressed form, in accordance with the pattern of repeat and non-repeat data indicated by said new map if said new map was received from said means for transmitting, or in accordance with the pattern indicated by said last map, by selecting said repeat data from said means for storing the last plurality of data and by selecting said non-repeat data received from said means for transmitting.

Claim 5

Apparatus as in claim 1 wherein both said first buffer means and said second buffer means are shift registers and wherein each of said pluralities of data comprise a plurality of data characters, said means for comparing coupled to compare characters in said first and second buffer means as said characters are shifted therefrom to determine whether said characters are repeat or non-repeat characters, said means for generating said new map comprising: A. a new map register, said new map register comprising a plurality of character locations coupled for shifting characters therebetween, the first location of said new map register coupled for enabling a counting function; B. means for counting in said first location of said new map register each time a comparison is made by said means for comparing; C. means for shifting the count from said first location to the next location in said new map register each time a boundary between a group of repeat characters and a group of non-repeat characters is detected; and D. means for restarting the count of said counting function in said first location each time said count is shifted from said first location, whereby said new map is generated in said new map register with alternating counts representative of the number of repeat or non-repeat characters by groups.

Claim 6

Apparatus as in claim 4 further comprising: A. means, coupled with said means for comparing and said new map register, for indicating the number of characters to be transmitted if said new map is also to be transmitted; and B. means, coupled with said new map register, for indicating the number of counts in said new map, the number of counts in said new map representative of the number of groups of repeat and non-repeat characters.

Claim 7

Apparatus as in claim 4 wherein said means for determining, whether said old map reflects substantially the same numbers of repeat and non-repeat data as does said new map, comprises: A. means for comparing the characters shifted from said first and second buffer means to determine whether they do not match; B. an old map which indicates the numbers of repeat and non-repeat characters detected between two successive, previously compared pluralities of data; C. means, responsive to said old map and coupled with said means for comparing the characters shifted from said buffer means, for generating a first signal if there is a no match condition when said characters are shifted from both said buffer means and if said old map indicates that repeat characters are being so shifted, said first signal indicating that said old map cannot be used and that said new map must be used by said means for transmitting for transmitting said non-repeat characters.

Claim 8

Apparatus as in claim 6 further including decision logic comprising: A. means for determining a first quantity of characters which would be transmitted if by use of the old map only the non-repeat characters are transmitted; B. means for determining a second quantity of characters which would be transmitted if by use of the new map, both the new map and the non-repeat characters are transmitted; C. means for determining the smaller of said first quantity and a third quantity which is the sum of a predetermined fraction of the characters in said new map plus the number of non-repeat characters; and D. means, coupled with said means for transmitting, for enabling the transfer of said characters associated with the smaller quantity.

Claim 9

Data communications apparatus comprising: A. a first shift register having a plurality of positions, each for storing one data representation of a first group of data representations; B. a second shift register having a plurality of positions, each for storing one data representation of a second group of data representations; C. means for shifting data representations of said first and second groups from said first and second registers respectively; D. means for comparing a data representation of said first group with a data representation of said second group each time said data representations are shifted by said means for shifting, said means for comparing generating a match signal if said data representations compare and a no-match signal if said data representations do not compare; E. map register means having a first position coupled for receiving first signals and for counting the number of said first signals received, and having a plurality of further positions, said plurality of further positions and said first position coupled in a shift register arrangement in order to enable the counted number of first signals in said first position to be shifted into said further positions; F. means, responsive to either said match or no match signals, for generating said first signal and enabling the counting in said first positions; G. means, coupled with said means for comparing and responsive to a change from the generation of said match signal to the generation of said no match signal or vice-versa, for shifting the count in said first position to the next one of said further positions and for shifting the counts in said further positions; and H. means, coupled with said map register means and said second shift register, for transmitting data representations from said second shift register which are not the same as data representations in like positions of said first shift register.

Claim 10

Data communications apparatus comprising: A. a first shift register having a plurality of positions, each for storing one data representation of a first group of data representations; B. a second shift register having a plurality of positions, each for storing one data representation of a second group of data representations; C. means for shifting data representations of said first and second groups from said first and second registers respectively; D. means for comparing a data representation of said first group with a data representation of said second group each time said data representations are shifted by said means for shifting, said means for comparing generating a match signal if said data representations compare and a no-match signal if said data representations do not compare; E. map register means having a first position coupled for receiving first signals and for counting the number of said first signals received, and having a plurality of further positions, said plurality of further positions and said first position coupled in a shift register arrangement in order to enable the counted number of first signals in said first position to be shifted into said further positions; F. means, responsive to either said match or no match signals, for generating said first signal and enabling the counting in said first positions; G. means, coupled with said means for comparing and responsive to a change from the generation of said match signal to the generation of said no match signal or vice-versa, for shifting the count in said first position to the next one of said further positions and for shifting the counts in said further positions; and H. means, coupled with said map register means and said second shift register, for transmitting data representations from said second shift register which are not the same as data representations in like positions of said first shift register.

Claim 11

Apparatus as in claim 8 wherein said means for transmitting comprises: A. means for generating a second signal for each of the counts included in the positions of said map register means which counts represent data representations which are repetitive, and a third signal for each one of such counts which represent data representations which are non-repetitive; B. means, responsive to said second signal, for disabling the transmission of said data representations which are repetitive; and C. means, responsive to said third signal, for enabling the transmission of said data representations which are non-repetitive.

Claim 12

Apparatus as in claim 8 wherein said data representations in said first register represent a further group of data characters which have been previously transmitted and wherein said data representations in said second register represent a second group of data characters which are to be presently transmitted.

Claim 13

Apparatus as in claim 10 wherein said means for transmitting further comprises: A. an old map register for storing the counts generated by said map register means in association with the transmission of said first group of data characters; B. means for transferring said second group of data characters using said counts stored in said old map register if said counts in said new map register means substantially compare with the counts in said old map register; and C. means for transferring the contents of said new map register means, if said counts in said new map register means do not substantially compare with the counts in said old map register.

Claim 14

Apparatus as in claim 11 further comprising means for receiving said data characters and said counts in said new map register means from said means for transmitting, said means for receiving comprising: A. first means for storing the counts of said new map register means last received by said means for receiving; B. second means for storing the last group of data characters transmitted to said means for receiving; C. means, coupled with said second means for storing, for decompressing the presently received groups of said data characters in accordance with the pattern of counts in said first means for storing, if the counts generated in association with said presently received group of data characters is not received; D. third means for storing the counts of said new map register means presently received with said presently received group of data characters; and E. means, coupled with said second means for storing, for decompressing the presently received group of data characters in accordance with the pattern of counts in said third means for storing.

Claim 15

A machine implemented process comprising the steps of: A. providing by means of a first buffer means a first plurality of data representative of the present data to be compressed; B. providing by means of a second buffer means a second plurality of data representative of data previously compressed; C. comparing the individual data in said first buffer means with the individual data in said second buffer means; D. generating, in response to the comparison made during said step of comparing, a new map indicating, in the order of comparison, the number of repeat data and the number of non-repeat data detected between said first and second pluralities of data; and E. transmitting, in response to said step of generating, only those individual data of said first plurality of data which are detected to be non-repeat data as indicated by said new map.

Claim 16

A machine implemented process comprising the steps of: A. providing by means of a first buffer means a first plurality of data representative of the present data to be compressed; B. providing by means of a second buffer means a second plurality of data representative of data previously compressed; C. comparing the individual data in said first buffer means with the individual data in said second buffer means; D. generating, in response to the comparison made during said step of comparing, a new map indicating, in the order of comparison, the number of repeat data and the number of non-repeat data detected between said first and second pluralities of data; and E. transmitting, in response to said step of generating, only those individual data of said first plurality of data which are detected to be non-repeat data as indicated by said new map.

Claim 17

A process as in claim 13 further comprising the steps of: A. providing an old map which indicates the number of repeat data and the number of non-repeat data detected between two successive, previously compared pluralities of data; B. determining whether said old map reflects substantially the same numbers of repeat and non-repeat data as does said new map; and C. additionally transmitting said new map if said old map does not reflect substantially the same numbers of repeat and non-repeat data as does said new map.

Claim 18

A process as in claim 14 further comprising the steps of decompressing said data received in compressed form, said step of decompressing comprising the steps of: A. storing the last plurality of data received; B. storing the last map received; and C. regenerating said data in decompressed form, in accordance with the pattern of repeat and non-repeat data indicated by said new map if said new map was received, or in accordance with the pattern indicated by said last map, by selecting the stored ones of said repeat data of the last plurality of data and by selecting said non-repeat data received.

Claim 19

A process as in claim 13 wherein both said first buffer means and said second buffer means are shift registers and wherein each of said pluralities of data comprise a plurality of data characters, said steps of comparing coupled to compare characters in said first and second buffer means as said characters are shifted therefrom to determine whether said characters are repeat or non-repeat characters, said steps of generating said new map comprising the steps of: A. providing a new map register, said new map register comprising a plurality of character locations coupled for shifting characters therebetween, the first location of said new map register coupled for enabling a counting function; B. counting in said first location of said new map register each time a comparison is made during said step of comparing; C. shifting the count from said first location to the next location in said new map register each time a boundary between a group of repeat characters and a group of non-repeat characters is detected; and D. restarting the count of said counting function in said first location each time said count is shifted from said first location, whereby said new map is generated in said new map register with alternating counts representative of the number of repeat or non-repeat characters by groups.

Claim 20

A process as in claim 16 wherein said step of determining, whether said old map reflects substantially the same numbers of repeat and non-repeat data as does said new map, comprises the steps of: A. comparing the characters shifted from said first and second buffer means to determine whether they do not match; B. providing an old map which indicates the numbers of repeat and non-repeat characters detected between two successive, previously compared pluralities of data; C. generating, in response to said old map and to the characters shifted from said buffer means, a first signal if there is a no match condition when said characters are shifted from both said buffer means and if said old map indicates that repeat characters are being so shifted, said first signal indicating that said old map cannot be used and that said new map must be used during said step of transmitting for transmitting said non-repeat characters.