Information retrieval system and method

Claim 2

In a method for retrieving desired records of data, said records each including key data in a predetermined part thereof and said records each including first error check data iteratively developed from said record without said check data, by searching a plurality of sequentially and cyclically appearing records from data storage means by reading said predetermined part of said records for comparison thereof to a search argument supplied by a search request, the improvement thereto comprising: conducting a search of each said record by sequential comparison of said predetermined part of said record with said supplied search argument until a point of non-comparison is detected thereby, storing, in response to said search, a signal indication of the result of said search; iteratively developing second error check data from said record; decoding said first and second error check data to provide an error signal indication of the occurrence and location of any error in said record and providing an error signal upon any said error location being prior to and inclusive of said point of non-comparison; selecting, in response to the absence of said error signal, said stored result of said search as being correct; and providing a signal in response to the presence of said error signal, indicating said search is in error.

Claim 3

The method of claim 1, including: the additional step of providing point location signals in response to said detection of said non-comparison, said point location signals indicating the location in said record of said point of non-comparison; and wherein said ''''decoding'''' step comprises the steps of: decoding said first and second error check data to provide an error signal indicating the occurrence of any error in said record; further decoding said error check data, in response to said error signal, to provide error location signals indicating the location in said record of said errors; and comparing, in response to said error signal, said point location signals with said error location signals to provide a first error position signal upon said error location signals indicating a location in said record following that indicated by said point location signals; wherein said ''''selecting'''' step comprises selecting, independently in response to the absence of said error signal upon completion of said error detection, or to the absence of said first error position signal upon the completion of said ''''comparing'''' step, said stored result of said search as being corrected; and wherein said ''''providing'''' step comprises providing a signal, in response to the presence of said first error position signal upon completion of said ''''comparing'''' step indicating said search is in error.

Claim 4

The method of claim 2, including the additional steps of: storing, in response to said detection of said non-comparison, a portion of said record data including said point of non-comparison; conducting a second search of said record by comparison of the remainder of said predetermined part thereof immediately following said stored portion of said record, with the corresponding remainder of said supplied search argument; and storing, in response to said second search, a second signal indication of the result of said second search; and wherein said ''''comparing'''' step comprises comparing, in response to said error signal, said point location signals with said error location signals to provide one of the following a first error position signal upon said error location signals indicating a location in said record following that indicated by said point location signals; a second error position signal upon said error location signals indicating the same location in said record as that indicated by said point location signals; or a third error position signal upon said error location signals indicating a location in said record preceding that indicated by said point location signals; and said ''''selecting'''' step comprises selecting said stored result of said first search as being correct, independently in response to the absence of said error signal upon the completion of said error detection, or to the presence of said third error position signal upon the completion of said ''''comparing'''' step; and said method of claim 2 also including the additional steps of: correcting in response to said second error position signal, said detected errors in said stored portion of said record by further decoding said error check data therewith; conducting a third search by comparison of said corrected portion of said record with the corresponding portion of said supplied search argument, and providing a third signal indication of the result of said third search; selecting, in response to said third signal indication indicating that said compared portions are the same, said stored result of said second search as being correct; and selecting, in response to said third signal indication indicating that said compared portions are not the same, said third signal indication of the result of said third search as being correct.

Claim 5

The method of claim 3, wherein: said ''''comparing'''' step comprises comparing, in response to said error signal, said point location signals, modified by predetermined constants to indicate the beginning and end locations in said record of said stored portion of said record data, with said error location signals to provide one of the following: a first error position signal upon said error location signals indicating a location in said record following that of the end of said stored portion indicated by said modified point location signals; a second error position signal upon said error location signals indicating said error locations in said record are between those of the beginning and end of said stored portion indicated by said modified point location signals; or a third error position signal upon said error location signals indicating a location in said record preceding that of the beginning of said stored portion indicated by said modified point location signals.

Claim 6

The method of claim 4, including the additional steps of: conducting, in response to the presence of said first error position signal upon completion of said ''''comparing'''' step, another first and second search of said record by sequential comparison of said predetermined part thereof with said supplied search argument; storing, in response to said another search, a signal indication of the result of said another search; during said another first and second search, storing, in response to said another search and said error location signals, another portion of said record data at the location in said record indicated by said error location signals; iteratively developing third error check data from said record; decoding said first and third error check data to provide a second error signal indicating the occurrence of any error in said record prior to and inclusive of said location indicated by said error location signals; selecting, in response to the absence of said second error signal, said stored result of said another search as being correct; correcting, in response to said second error signal, said stOred another portion of said record data by further decoding said first and third error check data therewith; conducting, in response to said correction of said stored another portion of said record, a last search of said record by comparison of said predetermined part thereof with said supplied search argument, substituting said corrected another portion of said record for said another portion as read from said record; storing, in response to said last search, a signal indication of the result of said last search; iteratively developing fourth error check data from said record including said substituted data; decoding said first and fourth error check data to provide a third error signal indicating the occurrence of any error in said record; and selecting, in response to the absence of said third error signal upon completion of said last ''''decoding'''' step, said stored result of said last search as being correct; and wherein: said ''''providing'''' step comprises providing a signal, in response to said third error signal, indicating said search is in error and uncorrectable by this procedure.

Claim 7

The method of claim 5, wherein said ''''selecting'''' steps and said ''''providing'''' steps each include supplying said selected and provided signals to an output means.

Claim 8

The method of claim 6 for retrieving said desired records of data from data storage devices having relatively slow data access speeds, wherein: said ''''storing'''' steps each comprise storing said signals in a storage means having relatively high data access speeds.

Claim 9

In apparatus for retrieving desired data records, said data records each including key data in a predetermined part thereof and each including first error check data iteratively developed from said record without said check data, from a selected data storage device, said device repetitively supplying a string of said data records for reading, said apparatus including device control means for controlling the reading of said supplied data by said device, read data means for receiving said data as read, interface means for receiving externally supplied search request signals and associated search argument signals and to which signals are supplied for communication with external apparatus, buffer memory means for storing data signals, logic means for selectively operating on supplied data signals, and control and transmission means for controlling the operation of all said means and for controlling the transfer of data signals between said means; said control and transmission means being arranged to respond to said search request signals when received by said interface means to store said associated search argument signals in said buffer memory means, to cause said device control means to cause the reading by said device of said records to supply the data read from each said record to be received by said read data means, and to cause said key data of said record and said search argument from said buffer memory means to be transmitted to said logic means for comparison therebetween sequentially therealong; the combination therewith comprising: error detection generator means controlled by said control means for iteratively developing error check data from any data records supplied thereto; error detection decoding means for decoding said developed error check data and said error check data included with said record to detect thereby errors in said record and the location in said record of said errors; and the arrangement of said control and transmission means to additionally comprise means for operating said logic means to indicate the location in said record that said comparison thereby detects a point of non-comparison; means for responding to said detection to store point location signals from said logic means indicating said location and to store search result signals indicating the result of said comparison in said buffer memory means; means for transmitting said record to said error detection means and operating said error detection means to provide an error signal upon detecting an error in said record and to thereupon supply error location signals indicating said location in said record of said errors; means for responding to said error signal by transmitting said stored point location signals and said error location signals to said logic means for comparison therebetween to thereby provide a first error position signal upon said error location signals indicating a location in said record following that indicated by said point signals; means for responding independently to the absence of said error signal upon completion of the operation of said error detection means, or to the absence of said first error position signal upon completion of said operation of said logic means, to transmit said stored search result signals from said buffer memory means to said interface means; and means for responding to said first error position signal by supplying a predetermined set of signals, said signals indicating said search is in error.

Claim 10

In apparatus for retrieving desired data records, said data records each including key data in a predetermined part thereof and each including first error check data iteratively developed from said record without said check data, from a selected data storage device, said device repetitively supplying a string of said data records for reading, said apparatus including device control means for controlling the reading of said supplied data by said device, read data means for receiving said data as read, interface means for receiving externally supplied search request signals and associated search argument signals and to which signals are supplied for communication with external apparatus, buffer memory means for storing data signals, logic means for selectively operating on supplied data signals, and control and transmission means for controlling the operation of all said means and for controlling the transfer of data signals between said means; said control and transmission means being arranged to respond to said search request signals when received by said interface means to store said associated search argument signals in said buffer memory means, to cause said device control means to cause the reading by said device of said records to supply the data read from each said record to be received by said read data means, and to cause said key data of said record and said search argument from said buffer memory means to be transmitted to said logic means for comparison therebetween sequentially therealong; the combination therewith comprising: error detection generator means controlled by said control means for iteratively developing error check data from any data records supplied thereto; error detection decoding means for decoding said developed error check data and said error check data included with said record to detect thereby errors in said record and the location in said record of said errors; and the arrangement of said control and transmission means to additionally comprise means for operating said logic means to indicate the location in said record that said comparison thereby detects a point of non-comparison; means for responding to said detection to store point location signals from said logic means indicating said location and to store search result signals indicating the result of said comparison in said buffer memory means; means for transmitting said record to said error detection means and operating said error detection means to provide an error signal upon detecting an error in said record and to thereupon supply error location signals indicating said location in said record of said errors; means for responding to said error signal by transmitting said stored point location signals and said error location signals to said logic means for comparison therebetween to thereby provide a first error position signal upon said error location signals indicating a location in said record following that indicated by said point signals; means for responding independently to the absence of said error signal upon completion of the operation of said error detection means, or to the absence of said first error position signal upon completion of said operation of said logic means, to transmit said stored search result signals from said buffer memory means to said interface means; and means for responding to said first error position signal by supplying a predetermined set of signals, said signals indicating said search is in error.

Claim 11

The apparatus of claim 8 wherein: said error detection means also comprises error correction means for decoding said error check data together with supplied data of said record containing said errors to correct said errors; and said control and transmission means is additionally arranged to comprise means for responding to said detection of a point of non-comparison by said logic means to store a portion of said record immediately spanning said point of non-comparison in said buffer memory means means for responding to said storage to continue to supply said key data of said record and said search argument to said logic means for second comparison; means for responding to said continued comparison to supply second search result signals representing the result thereof from said logic means to said buffer memory means; means for operating said logic means in response to said error signal to additionally provide a second error position signal upon said error location signals indicating the same location as that indicated by said point location signals, or a third error position signal upon said error location signals indicating a location preceding that indicated by said point location signals; said means for independently responding to the absence of said first error position signal being for responding independently to said third error position signal; means for transmitting said stored portion of said record to said error detection and correction means for correction thereof; means for responding to said correction to transmit said corrected portion of said record and the corresponding portion of said stored supplied search argument signals to said logic means for third comparison therebetween means for responding to said third comparison indicating said compared portions are the same to transmit said stored second search result to said interface means; and means for responding to said third comparison indicating said compared portions are not the same to transmit signals indicating the result of said third comparison from said logic means to said interface means.

Claim 12

The apparatus of claim 9 wherein: said data storage device comprises one of a plurality of devices having relatively slow data access speeds; and said buffer memory means comprising a data storage means having relatively high data access speeds.

Claim 13

The apparatus of claim 9 additionally including: error encoder means for initially iteratively developing said first error check data for each said record; and write data means for holding supplied data for transmission to said device, and wherein: said device control means additionally includes means for controlling the writing of data in said device; and said control and transmission means is additionally arranged to comprise means for responding to externally supplied write request and data at said interface means to supply said data to said error encoder and said encodeD data to said write data means; and means for operating said device control means to control said device to write said supplied data from said write data means in said device.