A semiconductor device includes a first die connected to a first channel, the first die comprising a first memory chip; and a second die connected to a second channel, the second die comprising a second memory chip, the first and second channels being independent of each other and a storage capacity and a physical size of the second die being the same as those of the first die. The first and second dies are disposed in one package, and the package includes an interconnection circuit disposed between the first die and the second die to transfer signals between the first memory chip and the second memory chip.