A controller of a flash memory device exchanges data pages with the memory device via a host-type NAND interface and exchanges data sectors with a host via a flash-type NAND interface. The data sectors are different in size than the data pages. A data storage system includes the controller and the memory device. Another data storage system includes a memory whose physical pages have a common size and circuitry for exporting a flash-type NAND interface for exchanging data sectors, that differ in size from the physical pages, with a host. A data processing system includes the data storage system and the host.