| 摘要 |
PURPOSE:To read out a correct content from a readout-only memory cell array when an error exists in the storing content of the memory cell array by reading out the data indicating the error in corresponding to the address and writing the read-out data in a writable memory cell array. CONSTITUTION:In the first place, '1' is written in all cells of a RAM cell array 12 to be checked. Then contents of a normal ROM cell array 11 are checked by changing the address Am. If one of the contents of the array 11 does not coincide with an anticipated content, '0' is written in the array 12 while the address Am is kept as it is. When the checked contents coincide with anticipated contents, all cells are checked without change. Then the correct contents are written at a noncoincident address of a ROM cell array 21 for correction. After writing, the correct contents can be automatically read out from a terminal Rn depending upon the contents '0' or '1' written in the array 12. |
