Identification of faults in data paths and functional units of a central processing unit by a systematic execution of test instructions

Claim 2

A diagnostic method for locating faulty functional units and data paths in a central processing unit of a data processing circuit, said central processing unit having signal input and output terminals, said data paths connecting signals from and between said terminals and said functional units, said functional units modifying signals received though said data paths, comprising providing a first database of instructions, said instructions, when input as signals to terminals of said central processing unit, causing said central processing unit to use every data path and functional unit in said central processing unit, providing a second database correlating groups of said instructions to functional units and datapaths of said central processing unit which must be operating correctly to avoid an error during said groups of instructions, providing a third database of test procedures, each test procedure, when input as electrical signals to terminals of said central processing unit, causing the central processing unit to use specific data paths and functional units, and including a test for determining whether a data path or functional unit used by the central processing unit in response to said test procedure is faulty, said third database correlating said test procedures with specific data paths and functional units used in response to said test procedure, executing, in said central processing unit, each of said instructions in said first database by providing electrical signals corresponding to said instructions to terminals of said central processing unit, and forming a first log of errors identifying data paths and functional units which were found to be faulty during execution of said instructions, correlating groups of instructions which produced errors identified in said first log to said second database to form a second log of possibly faulty functional units and data paths in said central processing unit, selecting test procedures from said third database which are correlated to possibly faulty functional units and data paths identified by said second log, and performing, in said central processing unit, test procedures selected in the preceding step by providing electrical signals corresponding to said test procedures to terminals of said central processing unit, and forming a third log of those functional units and data paths indicated to be faulty by tests performed by said test procedures.

Claim 3

The method of claim 1 wherein said first database further comprises expected values indicating results which would be generated by a non-faulty central processing unit in response to instructions in said first database, said executing step includes comparing said expected values to electrical signals at terminals of said central processing unit indicative of results produced by said central processing unit in response to instructions in said first database, and if said values and results are not consistent, adding an error to said first log.

Claim 4

The method of claim 2 wherein said executing step forms said first log by generating, for at least one instruction which produces an error, information on the contents of registers in said central processing unit.

Claim 5

The method of claim 3 further comprising providing a fourth database of error messages identifying the nature of a fault, each said message being correlated to a possible fault in a functional unit or data path in said central processing unit, selecting error messages from said fourth database which are correlated to faulty functional units and data paths identified in said third log, and reporting said error messages.

Claim 6

The method of claim 4 wherein said error messages identify a functional unit or data path of said central processing unit which contains faulty circuitry.

Claim 7

The method of claim 1 wherein said executing step forms said first log by generating, for at least one instruction which produces an error, information on the contents of registers in said central processing unit.

Claim 8

The method of claim 6 further comprising providing a fourth database of error messages identifying the nature of a fault, each said message being correlated to a possible fault in a functional unit or data path in said central processing unit, selecting error messages from said fourth database which are correlated to faulty functional units and data paths identified in said third log, and reporting said error messages.

Claim 9

The method of claim 7 wherein said error messages identify a functional unit or data path of said central processing unit which contains faulty circuitry.

Claim 10

The method of claim 1 further comprising providing a fourth database of error messages identifying the nature of a fault, each said message being correlated to a possible fault in a functional unit or data path in said central processing unit, selecting error messages from said fourth database which are correlated to faulty functional units and data paths identified in said third log, and reporting said error messages.

Claim 11

The method of claim 9 wherein said error messages identify a functional unit or data path of said central processing unit which contains faulty circuitry.

Claim 12

Apparatus for locating faulty functional units and data paths in a central processing unit of a data processing circuit, said central processing unit having signal input and output terminals, said data paths connecting signals from and between said terminals and said functional units, said functional units modifying signals received through said data paths, comprising storage maintaining a first database of instructions, said instructions, when input as signals to terminals of said central processing unit, causing said central processing unit to use every data path and functional unit in said central processing unit, storage maintaining a second database correlating groups of said instructions to functional units and datapaths of said central processing unit which must be operating correctly to avoid an error during said groups of instructions, storage maintaining a third database of test procedures, each test procedure, when input as electrical signals to terminals of said central processing unit, causing the central processing unit to use specific data paths and functional units, and including a test for determining whether a data path or functional unit used by the central processing unit in response to said test procedure is faulty, said third database correlating said test procedures with specific data paths and functional units used in response to said test procedure, a diagnostic control circuit, said diagnostic control circuit causing said central processing unit to execute each of said instructions in said first database, by providing electrical signals corresponding to said instructions to terminals of said central processing unit, forming a first log of errors identifying data paths and functional units which were found to be faulty during execution of said instructions, correlating groups of instructions which produced errors identified in said first log to said second database to form a second log of possibly faulty functional units and data paths in said central processing unit, selecting test procedures from said third database which are correlated to possibly faulty functional units and data paths identified by said second log, and causing said central processing unit to perform test procedures selected in the preceding step, by providing electrical signals corresponding to said test procedures to terminals of said central processing unit, and forming a third log of those functional units and data paths indicated to be faulty by tests performed by said test procedures.

Claim 13

Apparatus for locating faulty functional units and data paths in a central processing unit of a data processing circuit, said central processing unit having signal input and output terminals, said data paths connecting signals from and between said terminals and said functional units, said functional units modifying signals received through said data paths, comprising storage maintaining a first database of instructions, said instructions, when input as signals to terminals of said central processing unit, causing said central processing unit to use every data path and functional unit in said central processing unit, storage maintaining a second database correlating groups of said instructions to functional units and datapaths of said central processing unit which must be operating correctly to avoid an error during said groups of instructions, storage maintaining a third database of test procedures, each test procedure, when input as electrical signals to terminals of said central processing unit, causing the central processing unit to use specific data paths and functional units, and including a test for determining whether a data path or functional unit used by the central processing unit in response to said test procedure is faulty, said third database correlating said test procedures with specific data paths and functional units used in response to said test procedure, a diagnostic control circuit, said diagnostic control circuit causing said central processing unit to execute each of said instructions in said first database, by providing electrical signals corresponding to said instructions to terminals of said central processing unit, forming a first log of errors identifying data paths and functional units which were found to be faulty during execution of said instructions, correlating groups of instructions which produced errors identified in said first log to said second database to form a second log of possibly faulty functional units and data paths in said central processing unit, selecting test procedures from said third database which are correlated to possibly faulty functional units and data paths identified by said second log, and causing said central processing unit to perform test procedures selected in the preceding step, by providing electrical signals corresponding to said test procedures to terminals of said central processing unit, and forming a third log of those functional units and data paths indicated to be faulty by tests performed by said test procedures.

Claim 14

The apparatus of claim 11 wherein said first database further comprises expected values indicating results which would be generated by a non-faulty central processing unit in response to instructions in said first database, said diagnostic control circuit compares said expected values to electrical signals at terminals of said central processing unit indicative of results produced by said central processing unit in response to instructions in said first database, and if said values and results are not consistent, adds an error to said first log.

Claim 15

The apparatus of claim 12 wherein diagnostic control circuit forms said first log by generating, for at least one instruction which produces an error, information on the contents of registers in said central processing unit.

Claim 16

The apparatus of claim 13 further comprising storage maintaining a fourth database of error messages identifying the nature of a fault, each said message being correlated to a possible fault in a functional unit or data path in said central processing unit, and wherein said diagnostic control circuit selects error messages from said fourth database which are correlated to faulty functional units and data paths identified in said third log, and reports said error messages.

Claim 17

The apparatus of claim 14 wherein said error messages identify a functional unit or data path of said central processing unit which contains faulty circuitry.

Claim 18

The apparatus of claim 11 wherein diagnostic control circuit forms said first log by generating, for at least one instruction which produces an error, information on the contents of registers in said central processing unit.

Claim 19

The apparatus of claim 16 further comprising storage maintaining a fourth database of error messages identifying the nature of a fault, each said message being correlated to a possible fault in a functional unit or data path in said central processing unit, and wherein said diagnostic control circuit selects error messages from said fourth database which are correlated to faulty functional units and data paths identified in said third log, and reports said error messages.

Claim 20

The apparatus of claim 17 wherein said error messages identify a functional unit or data path of said central processing unit which contains faulty circuitry.

Claim 21

The apparatus of claim 11 further comprising storage maintaining a fourth database of error messages identifying the nature of a fault, each said message being correlated to a possible fault in a functional unit or data path in said central processing unit, and wherein said diagnostic control circuit selects error messages from said fourth database which are correlated to faulty functional units and data paths identified in said third log, and reports said error messages.

Claim 22

The apparatus of claim 19 wherein said error messages identify a functional unit or data path of said central processing unit which contains faulty circuitry.

Claim 23

The apparatus of claim 11 wherein said diagnostic control circuit comprises circuitry separate from and communicating with said central processing unit.