US Patent 9767903 Nonvolatile memory module having dual-port DRAM

A memory module includes a nonvolatile memory device and a volatile memory device connected to a first data channel through a first input/output port and to a second data channel through a second input/output port. The volatile memory device activates one of the first and second input/output ports based on an operation mode. The memory module includes a registering clock driver that transmits a first control signal for data exchange through the first input/output port and a second control signal for data exchange through the second input/output port, to the volatile memory device. A memory controller of the memory module generates the second control signal, exchanges data with the volatile memory device through the second data channel, and controls the nonvolatile memory device. The memory controller detects a request from a host or a power status and generates the second control signal based on the detection result.