Portable data stack holder

A data storage device comprising:

• a plurality of tiles, a face of each tile marked with a character of a set of characters, each tile including a slot;
• an elongated core, a cross section of the core configured to enable a slot of each of the tiles to fit over an openable end of the core to mount that tile on the core, with the marked face of that tile aligned with the face of an adjacent tile that is mounted on the core, and to enable the tile to slide along the core, a length of the core being sufficient such that when a stack of a predetermined maximum number of the tiles is mounted on the core, some of the tiles of the stack are slidable away from other tiles of the stack to form a gap that is sufficiently long to enable reading the character that is marked on that tile;
• a locking element that is placeable on the openable end to prevent removal of a tile of the plurality of tiles from the stack, and removable from the openable end to enable addition of a tile of the plurality of tiles to the stack or removal of a tile of the plurality of tiles from the stack;
• and
• a casing that is closable over the core and that includes a limiting structure to limit sliding of the tiles along the core when the casing is closed over the core.