Abstract: When the determined result represents that a read request has been received, it is determined whether or not there is a read address that has been designated in a particular area. When the determined result represents that there is a read address that has been designated in the particular area, the process is terminated. In other words, the process is completed although data is not read. When the determined result represents that there is no read address that has been designated in the particular area, data is read from the designated address of the memory. The data that has been read is supplied to a host device. After the data has been read, a read address stored in for example a register is written to the particular area. The address from which data has been read is appended to the particular area. In such a manner, data that has been read from the host device is prohibited from being accessed.