Abstract: A digital memory is configured as a hierarchical system with at least three levels. The first level consists of a main bus and interfacing for one or more main memory units; the second level consists of a separate second level bus in each main memory unit with a plurality of memory frames independently interfaced to each bus; and the third level consists of a separate third level bus in each memory frame with a plurality of memory storage blocks independently interfaced to each bus. Virtual addressing is employed in which the whole of each address is decoded in the individual memory block which includes for the purpose soft-ware settable registers containing identification numbers.