| 摘要 |
PURPOSE:To replace the defective memory of a main memory with a redundant memory by writing the data to be written in the main memory in an unused address of the redundant memory when data written in the main memory and the data read out from the main memory after the data are written in the main memory do not coincide with each other. CONSTITUTION:When data are written in the nonvolatile memory of one address in a main memory array 8, the data written in the memory and the data read out from the memory after the data are written in the memory are compared with each other at a data comparator circuit 6 by reading out the written data. When both data do not coincide with each other, the circuit 6 outputs a comparison noncoincidence signal of an 'H' level. Upon inputting the noncoincidence signal, a redundancy control circuit 1 discriminates that the memory at the address of the main memory array 8 is defective and writes the data to be written in a memory belonging to the word line connected with the defective memory in a memory belonging to a specified word line of a redundant memory array 7. Thus the defective memory of the main memory can be replaced with the redundant memory. |
