| 摘要 |
A fault-tolerant magnetoresistive solid-state storage device (MRAM) in use performs error correction coding and decoding of stored information, to tolerate physical failures. At manufacture, the MRAM device is tested to confirm that each set of storage cells is suitable for storing ECC encoded data. The test comprises identifying failed storage cells where the failures will be visible in use for the generation of erasure information used in ECC decoding, suitably by comparing parametric values obtained from the storage cells against one or more failure ranges, and includes performing a write-read-compare operation with test data to identify failed storage cells which will be hidden for the generation of erasure information in use. A failure count is formed based on both the visible failures and the hidden failures, to determine that the set of storage cells is suitable for storing ECC encoded data. Here, the failure count is weighted, with hidden failures having a greater weighting than visible failures. Where a set of storage cells is determined as unsuitable, remedial action is taken to avoid future use of those cells.
|
