US Patent 10031879 Memory device for a hierarchical memory architecture

In various embodiments, a hierarchical memory device having multiple interfaces with different memory formats includes a Phase Change Memory (PCM). An input port and an output port connect the hierarchical memory device in a daisy-chain hierarchy and/or a hierarchical tree structure with other memories. Standard non-hierarchical memory devices can also attach to the output port of the hierarchical memory device. Other embodiments are discussed.