Multi-parallel-channel error checking
AssigneeBurroughs Corporation
InventorHerbert U. Ragle
Life of this patent
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Abstract
Disclosed is a technique for error checking in one channel or a pair of channels of a binary system in which communications is serial-by-character and parallel-by-bit, such as in digital computer-controlled magnetic tape peripherals. The system is shown as applied to the group coded recording (GCR) format and standard for half-inch, nine-track magnetic tape used for interchange among information processing systems (the USA Standard Code for Information Interchange). The technique employs equipment which generates and records on the tape, together with a set of information characters, a check (i.e., redundant) character and parity bits, the former resulting from the employment of a cyclic code and the latter being based on odd modulo 2 addition.
Claims12
In an automatically performable, electronically implemented error checking and correcting method for use in conjunction with a multichannel digital signal transfer system, the steps of:
- assembling the digital signals which are to be transferred into a plurality of multicharacter data words of common character bit length arranged so that each character is in a cross-channel direction with like bits of different characters in respective channels;
- generating a check character having said common character bit length in response to the bits contained in each data word to be transferred using a cyclical code chosen so that the resulting check character can be logically combined with its respective data word to provide a representation of single bit errors as a set of unique ordered syndrome matrices, one for each channel, said matrices being related to each other in a manner such that the product resulting from the multiplication of a vector by one matrix is equal to the product of the same vector and the next higher order matrix shifted in a predetermined direction, each syndrome matrix containing a plurality of different error patterns respectively corresponding to single bit errors occuring in particular bit positions of the respective channel;
- appending each generated check character to its respective data word in the same cross-channel direction as the other characters in the word;
- logically combining the check character and data word of a transferred data group to form an error pattern vector representative of bit errors therein;
- generating a first product of said error pattern vector and a first one of said syndrome matrices;
- and
- generating a second product of said error pattern and a second one of said matrices by shifting said first product a predetermined number of times in a predetermined direction as determined by the difference in the orders of said first and second matrices.
In an error checking and correcting system for use in a multichannel digital signal transfer system, the combination comprising:
- means for assembling the digital signals which are to be transferred into a plurality of multicharacter data words of common character bit length arranged so that each character is in a cross-channel direction with like bits of different characters in respective channels;
- means for generating a check character having said common character bit length in response to the bits contained in each data word to be transferred using a cyclical code chosen so that the resulting check character can be logically combined with its respective data word to provide a representation of single bit errors as a set of unique ordered syndrome matrices, one for each channel, said matrices being related to each other in a manner such that the product resulting from the multiplication of a vector by one matrix is equal to the product of the same vector and the next higher order matrix shifted in a predetermined direction, each syndrome matrix containing a plurality of different error patterns respectively corresponding to single bit errors occuring in particular bit positions of the respective channel;
- means for appending each generated check character to its respective data word in the same cross-channel direction as the other characters in the word;
- means for logically combining the check character and data word of a transferred data group to form an error pattern vector representative of bit errors therein;
- means for generating a first product of said error pattern vector and a first one of said syndrome matrices;
- and
- shifting means to which said first product is applied for generating a second product of said error pattern vector and a second one of said matrices by shifting said first product a predetermined number of times in a predetermined direction as determined by the difference in the orders of said first and second matrices.
Dependencies are inferred from the claim text.