Abstract: In a computer RAM memory system, the memory is subjected to a self test operation during which data is written to and read out from each address location of the memory. The data read out is compared with the written data to detect errors and the number of errors at each bit position is counted. When the number of errors in a bit position-exceeds a selected threshold, the corresponding DRAM is replaced by a spare DRAM. When the self test detects two or more errors in the same double word, the DRAM corresponding to the bit position having the highest error count is replaced with a spare DRAM. The memory is periodically scrubbed and errors detected during the scrubbing operation are counted for each bit position. At the end of the scrubbing of a chip row the DRAMs corresponding to bit positions at which the error counts exceed a selected threshold are replaced with spare DRAMs. When a multiple bit error in a double word is detected during scrubbing, the corresponding double word is tagged.

Abstract: In a memory card, identification numbers identifying the memory card are permanently stored in fuse blown registers formed in each of two redrive chips, which function to read out data from memory chips of the memory card and store data in the memory chips of the memory card. Each identification number separately provides a unique identification of the memory card. The identification numbers are each stored with an error correction code by which single bit errors en the identification numbers can be corrected and the occurrence of multiple bit errors in the identification numbers can be detected. Both identification numbers, if valid, are used to identify the memory card and both of the identification numbers, if valid, are stored in association with memory quality events occurring on the memory card, so as to provide a redundant identification of the memory card on which the memory quality events occurred.