| 摘要 |
PURPOSE:To improve the operating efficiency by handling a storage element constituting a storage section of the normal system while the element is divided into plural blocks in terms of address and forming an alternate memory preserved in advance similarly so as to make it alternative in the unit of blocks. CONSTITUTION:A storage unit M constituting a normal system memory group is an independent element sectional physically and electrically and replaced in failure. The element is divided into N blocks (four in Fig.). Furthermore, storage units A, (A-D, four in total in Fig.) of replacing memory corresponding to each block are prepared. If a fixed fault takes place in the memory, the block including the faulty part is replaced with one block of the replaced memory. Thus, even if plural small faults take place, the memory is replaced with a replacing memory of a small capacity and even if all the storage units are faulty, they are replaced with plural replacing memories. |
