| 摘要 |
<p>PROBLEM TO BE SOLVED: To quickly test existence of an erasion faulty cell by applying this method to a simple memory tester having no complex processing function such as a mask function and the like. SOLUTION: Storage performance of each cell is tested, data of all cells of a flash memory is written for a flash memory in which the number of storage faulty cells (n) is found, and the number of storage faulty cells (n) is set to a memory tester register. Erasion of data of all cells is repeated by N times, each data is read out in the order of address for each erasion, whenever read out data is faulty, 1 is subtracted from the number of set of a register. As a result of erasion of N times and subtraction of 1, it is discriminated that when the residual number n' of the register is 0, an erasion faulty cell does not exist in the flash memory, and when the residual number n' is smaller than 0, erasion faulty cells of (n'-n) pieces exist.</p> |
