JPS6450144A - Memory checking system - Google Patents

Abstract

PURPOSE:To detect an abnormal state of a memory by adding each data at every line and comparing it with a normal value, shifting a data of each address of the memory, adding it at every line, comparing it with the normal value, and deciding it to be normal, only when both of them have coincided with the normal value. CONSTITUTION:A data 100 which has been read out of a memory is inputted to the first decision train generating means 1 and the second decision train generating means 2. The means 1 derives the sum of every line of the data, derives a decision train consisting of the sum of each line and inputs it to a comparing means 3. The means 3 compares the input and the train consisting of a normal value, and H, and L are outputted to an AND circuit 5, when both have coincided, and at the time of discrepancy, respectively. The means 2 shifts the input data and makes out a decision train Y, and outputs it to a comparing means 4. The means 4 compares the train consisting of the normal value which has been derived in advance, and the decision train Y, and H, and L are outputted to the circuit 5, when both have coincided, and at the time of discrepancy, respectively. The circuit 5 takes AND of the means 3, 4, and a final deciding signal for deciding whether the memory is normal or abnormal is outputted.