A system that includes a multiplicity of flash memory cells; a reading apparatus; a writing apparatus for writing logical data from temporary memory into individual flash memory cells from among said multiplicity of flash memory cells, thereby to generate a physical representation of the logical data including a plurality of physical levels at least some of which represent, to said reading apparatus, at least one bit-worth of said logical data; and a special cell marking apparatus operative to store an earmark in at least an individual one of said multiplicity of flash memory cells for subsequent special treatment.