The Taub Faculty of Computer Science Events and Talks

Flash memories is a non-volatile technology that is both electrically programmable and electrically erasable. It incorporates a set of cells maintained at a set of levels of charge to encode information. While raising the charge level of a cell is an easy operation, reducing the charge level requires the erasure of the whole block to which the cell belongs, which is a slow operation and damages the life-time of the device. I will present some of our results regarding two coding schemes which overcome the common errors in flash memories. The first scheme I will present is Write-Once Memory (WOM) codes which allow to write multiple times to the memory without decreasing the levels of the cells. The second scheme is Rank Modulation (RM) in which the information is carried by the relative ranking of the cells' charge levels and not by their absolute values. This scheme provides a more efficient programming of cells and is more robust to charge leakage. I will also mention the reconstruction problem which is come up in the DNA-storage, another non-volatile technology.