| 摘要 |
PURPOSE:To prepare an address alteration table automatically by omitting data writing in an address alteration table at the stage of the initial production of a memory device using memory elements in which defective places exist at random and testing the table just before the use of it. CONSTITUTION:A data read out from a normal memory element MEM-N accessed by a normal address scanner ADS-N is stored in a register RDR-N and checked by a circuit CHK. When there is no error, valid indication is written in an address alteration table ATT by using a write data register WDR-T. A scanner ADS-N advances the address by 1 step and, if the address is the maximum address of the element MEM-N, the preparation of the table ATT is ended. When an error is detected, and circuit CHK inputs an alteration address A-A from an alteration address scanner ADS-A to an alteration memory element MEM-A and an address alteration table data register WDR-T. Then the alteration address is checked in the circuit CHK and, if there is no error, it is written in the table ATT. |
