Abstract: A data storage device includes a plurality of tiles whose faces are marked with characters. An elongated core is configured to enable slots of the tiles to fit over an openable end of the core to mount the tiles on the core with the marked faces aligned and to slide along the core. The length of the core is sufficient such that tiles of a mounted stack of tiles are slidable away from other tiles of the stack to form a gap that is sufficient to enable reading the character on the tile. A locking element is placeable on the openable end to prevent removal of tiles from the stack, and removable to enable addition of tiles or removal of tiles. A casing is closable over the core and includes a limiting structure to limit sliding of the tiles when the casing is closed.