A data processing system may include a memory/storage circuit and a host. The memory/storage circuit may include a first memory module and a second memory module. Each of the first and second memory modules may include a controller and a memory device. The host may have access to the memory device of the first memory module and the memory device of the second memory module. Each of the controllers included in the first and second memory modules may be configured to selectively perform any one of a memory operation and a storage operation according to a request of the host.