A dual-chip package is disclosed which includes at least two memory chips each of which may contain buffer and flash memories having different address systems from each other. Each memory chip may include a register for storing first and second flag signals each indicative of selections of corresponding memory chips, a comparator circuit for comparing the first and second flag signals in the register with a reference signal to generate a flash access signal and a buffer access signal, and a controller for controlling the buffer memory and the flash memory in response to the flash access signal and the buffer access signal.