| 摘要 |
PROBLEM TO BE SOLVED: To attach and detach an external storage device without increasing the volume and number of components of the portable telephone set main body by providing the external storage device that is connected to the portable telephone set through the use of an I/O connector being an existing external interface, thereby unnecessitating the provision of an exclusive interface to the portable telephone set main body. SOLUTION: An external storage device 2 is composed of an I/O connector B9 to connect a data line, a serial parallel converter 10 that converts serial data into parallel data, an external storage circuit A11 for data write/read, and a backup battery 12 that is used to stored data stored in the external storage circuit A11. Then a built-in control program is used to control data written/read to/from an internal storage circuit 6 so as to be inputted/outputted from/to an I/O connector A8 being an existing interface specified for the portable telephone set 1 as serial data when a command is entered by key operation. |
