Abstract: A semiconductor memory device includes a buffer die and a plurality of memory dies. An error correction code (ECC) engine in one of the memory dies performs an RS encoding on a main data to generate a parity data and performs a RS decoding, using a parity check matrix, on the main data and the parity data. The parity check matrix includes sub matrixes and each of the sub matrixes corresponds to two different symbols. Each of the sub matrixes includes two identity sub matrixes and two same alpha matrixes, the two identity sub matrixes are disposed in a first diagonal direction of the sub matrix and the two same alpha matrixes are disposed in a second diagonal direction. A number of high-level value elements in a y-th row of the parity check matrix is the same as a number of high-level value elements in a (y+p)-th row.

Abstract: A memory controller includes an error correction circuit and a central processing unit (CPU) to control the error correction circuit. The error correction circuit includes an error correction code (ECC) decoder and a memory to store a parity check matrix. The ECC decoder performs an ECC decoding on a codeword read from the memory module to: (i) generate a first syndrome and a second syndrome, (ii) generate a decoding mode flag associated with a type of errors in the codeword based on the second syndrome and a decision syndrome, (iii) operate in one of a first decoding mode and a second decoding mode based on the decoding mode flag, and (iv) selectively correct one of a chip error associated with one of the data chips and one or more symbol errors in the codeword.

Abstract: A memory system includes a writable data memory and means for recognizing an error in a data word read out from the data memory, correcting the error, and storing the corrected data word at a new address in a free area of the data memory.