Error detecting and correcting system and method

Claim 1

An apparatus for detecting and correcting errors in an arithmetic-logical operation within a computing apparatus comprising: a first and second data register for storing the data in bytes upon which the arithmetic-logical operation is to be performed; a first and second parity register for storing the parity for each data byte within said first and second data registers; a first and second register for storing the residue of the data contained in said first and second data registers; an arithmetic-logical unit responsive to said first and second data registers for performing an arithmetic-logical function upon the data in said first and second data registers and outputting the results of said arithmetic-logical function; a residue calculation means responsive to said arithmeticlogical unit for calculating the residue of the data outputted from said arithmetic-logical unit; a parity calculator means responsive to said arithmetic-logical unit for calculating the parity of the data outputted from said arithmetic-logical unit; a parity prediction means responsive to said arithmetic-logical unit, said first and second data registers, and said first and second parity registers to predict for said arithmetic-logical function the parity for the given arithmetic-logical function being performed by said arithmetic-logical unit; a residue prediction means responsive to said first and second residue registers for predicting for said arithmetic-logical function the residue of the result being calculated by said arithmetic-logical unit; an error detection means responsive to said parity prediction means and said parity calculation means for determining the data byte at the output of said arithmetic-logical unit in which an error occurred; an error magnitude calculator means responsive to said residue prediction means and said residue calculation means for determining the difference between said predicted and said actual residue and the arithmetic sign of said difference; and error correction means responsive to said arithmetic-logical unit, said parity comparison means, and said error magnitude calculator means to adjust the data byte in error as indicated by said parity comparison means by the magnitude and sign indicated by said error magnitude calculator means.

Claim 2

An apparatus for detecting and correcting errors in an arithmetic-logical operation within a computing apparatus comprising: a first and second data register for storing the data in bytes upon which the arithmetic-logical operation is to be performed; a first and second parity register for storing the parity for each data byte within said first and second data registers; a first and second register for storing the residue of the data contained in said first and second data registers; an arithmetic-logical unit responsive to said first and second data registers for performing an arithmetic-logical function upon the data in said first and second data registers and outputting the results of said arithmetic-logical function; a residue calculation means responsive to said arithmeticlogical unit for calculating the residue of the data outputted from said arithmetic-logical unit; a parity calculator means responsive to said arithmetic-logical unit for calculating the parity of the data outputted from said arithmetic-logical unit; a parity prediction means responsive to said arithmetic-logical unit, said first and second data registers, and said first and second parity registers to predict for said arithmetic-logical function the parity for the given arithmetic-logical function being performed by said arithmetic-logical unit; a residue prediction means responsive to said first and second residue registers for predicting for said arithmetic-logical function the residue of the result being calculated by said arithmetic-logical unit; an error detection means responsive to said parity prediction means and said parity calculation means for determining the data byte at the output of said arithmetic-logical unit in which an error occurred; an error magnitude calculator means responsive to said residue prediction means and said residue calculation means for determining the difference between said predicted and said actual residue and the arithmetic sign of said difference; and error correction means responsive to said arithmetic-logical unit, said parity comparison means, and said error magnitude calculator means to adjust the data byte in error as indicated by said parity comparison means by the magnitude and sign indicated by said error magnitude calculator means.

Claim 10

A method of detecting and correcting errors for calculation operations within a computing apparatus, comprising the steps of: calculating by said computing apparatus the results for a calculational operation; calculating from said result the actual parity and the actual residue for that result; predicting according to the calculational operation a predicted parity and a predicted residue; comparing said predicted parity with said actual parity, the parity bits failing to compare indicating the byte within the calculational results which contain errors; determining the sign and magnitude difference between the predicted and actual residues; and adding the difference between the predicted and actual residues to the byte of data in the calculational results which has been indicated to be in error for failure of comparison of the predicted and actual parity bits for the calculational result.

Claim 11

A method of detecting and correcting errors for calculation operations within a computing apparatus, comprising the steps of: calculating by said computing apparatus the results for a calculational operation; calculating from said result the actual parity and the actual residue for that result; predicting according to the calculational operation a predicted parity and a predicted residue; comparing said predicted parity with said actual parity, the parity bits failing to compare indicating the byte within the calculational results which contain errors; determining the sign and magnitude difference between the predicted and actual residues; and adding the difference between the predicted and actual residues to the byte of data in the calculational results which has been indicated to be in error for failure of comparison of the predicted and actual parity bits for the calculational result.