a memory includes cells at intersections of word lines and bit lines , word and bit line selection mechanisms and a programming mechanism . the cells on each bit line are connected in series . cells of a word line are programmed simultaneously . for low - power reading , only some of the bit lines that intersect the word line at the programmed cells are selected and only the cells at those intersections are sensed . another type of memory includes a physical page of cells , a sensing mechanism and a selection mechanism . hard bits are sensed from all the cells of the physical page . only some of those cells are selected for sensing soft bits . another memory includes a plurality of cells , a sensing mechanism , an export mechanism and a selection mechanism . hard and soft bits are sensed from all the cells of the plurality . only some of the soft bits are selected for export .