INFORMATION PROCESSOR

PROBLEM TO BE SOLVED: To reduce the capacity of a buffer memory of a semiconductor memory device without increasing an interface bandwidth between a host device and the semiconductor memory device.SOLUTION: A host device separates a write request to a semiconductor memory device into a write command and write data corresponding to the write command, outputs the write command to the semiconductor memory device, and stores the write data in a main memory. The semiconductor memory device receives the write command that is transferred from the host device; causes the write data corresponding to the write command, which is stored in the main memory, to be transferred to the semiconductor memory device when executing the write command; and writes it to a nonvolatile semiconductor memory.