An interface device backs up printer settings and operating history data of printer so that the settings and history data can be easily restored. A nonvolatile memory 109 in the printer 101 stores printer settings data. Commands from a host 161 are passed by the interface device 131 and received by a receiver 103 within the printer. If the command data is a print command, the print mechanism 108 prints the specified text or image. If the command data is a command for updating the settings data, the corresponding settings data in the nonvolatile memory 109 is updated and at an appropriate backup time the updated settings data is copied to a nonvolatile memory 135 in the interface device 131. The settings data backed up into the interface device 131 can then be restored back to the printer's nonvolatile memory 109 at an appropriate data restore time.