A computing system and a memory device are provided. The memory device includes a first memory having a first storage capacity. A second memory is also provided having a second storage capacity greater than the first storage capacity. The memory device also includes a controller to provide an external host with an address space corresponding to a third storage capacity, the third storage capacity being less than a sum of the first storage capacity and second storage capacity. The controller transmits the requested data to the external host from the first memory where data requested from the external host is stored in the first memory, and where the requested data is not stored in the first memory, transmits the requested data to the external host from the second memory.