A system includes a host device, an external bus and a storage device. A driver is installed in the host device. The external bus is connected with the host device. The external bus supports a communication protocol. The storage device includes a controlling circuit and a non-volatile memory. After the storage device issues a request to the host device according to the communication protocol, a reserved space is created in a host memory of the host device in response to the request, and a device information from the storage device is stored into the reserved space. While the host device issues a first command to operate the storage device, the first command is converted into a second command by the driver according to the device information, and then the second command is transmitted to the storage device.