Israel Institute of Technology
The level of write-once memory cells (e.g., Flash) can only be raised individually. Bulk erasure is possible, but only a number of times (endurance) that decreases sharply with increasing cell capacity or cell-size reduction. A device's declared storage capacity and the total amount of information that can be written to it over its lifetime thus jointly characterize it. Write-Once Memory (WOM) coding permits a trade-off between these, enabling multiple writes between erasures. The guaranteed (over data) number of such writes is presently considered the important measure.