Described is a technology by which a memory controller is a component of a hybrid memory device having different types of memory therein (e.g., SDRAM and flash memory), in which the controller operates such that the memory device has only a single memory interface with respect to voltage and access protocols defined for one type of memory. For example, the controller allows a memory device with a standard SDRAM interface to provide access to both SDRAM and non-volatile memory with the non-volatile memory overlaid in one or more designated blocks of the volatile memory address space (or vice-versa). A command protocol maps memory pages to the volatile memory interface address space, for example, permitting a single pin compatible multi-chip package to replace an existing volatile memory device in any computing device that wants to provide non-volatile storage, while only requiring software changes to the device to access the flash.