A device can receive information to be stored in a first part of a first portion of a block, read previously-stored information from a second part, and store the specified information in the first part and simulate storage of the previously-stored information in the second part while generating error detection information which is then stored in a second portion of the block. The device can read a specified subset of sections in a block, use part of each section to detect and/or correct an error in another part thereof, while avoiding reading the error detection information unless a section in the subset has an uncorrected error. Detected errors are corrected with successive correction stages, while maintaining for each section being processed in the stages a count of the number of other sections which are thereafter read in succession without error.