A main memory (10) comprises a plurality of physical blocks of memory locations. The main memory (10) supports erasing of at least a physical block at a time. Pointer information is stored in a subset (40, 42) of the blocks for use to identify respective ones of the physical blocks that are assigned to respective functions. Successive versions of the pointing information are stored at mutually different memory locations initially in a first block (40) in the subset (40, 42). A subsequent version of the pointing information that is more recent than the successive versions is stored in a second block (42) of the subset (40, 42) at least after the first block (40) has been filled. The first block (40) is erased after storing the subsequent version. On start up of the main memory the pointing information is recovered by testing which of the blocks of the subset (40, 42) contains a most recent version of the pointing information.
