Abstract: A digital memory system comprises a wafer full of uncomitted but interconnectable memory cells and a controller acting as an interface between the wafer and a host system. Each cell comprises input logic to allow coupling thereto from just one other neighboring cell and output logic allowing a cell to be commanded by the controller to couple to any selectable one other neighboring cell not already so coupled to. The controller accesses the wafer via a port and successively tests and couples cells from the port to form a chain of memory cells. Each cell comprises a plurality of individually selectably usable data storage loops and allows a cell to be used even if the loops are not fully functional by the provision of through-passing data transfer path.