| 摘要 |
PROBLEM TO BE SOLVED: To realize a complete resume function for preventing a customer from having any feeling of distrust on a restored sales registration processing. SOLUTION: Display data and transmission number data are transmitted as a data packet, and the display data and the transmission number data are stored in non-volatile storage parts 21 and 22 so that even when a power source is disconnected, the display data and the transmission number data can be prevented from being lost. Also, even when the display data are lost due to power source disconnection in the middle of transmission, the transmission command of the data packet decided based on the transmission number data of the display data stored in the storage parts 21 and 22 is transmitted so that the re-transmission of the display data lost due to the power source disconnection can be attained, and the lost data can be restored. Thus, the display of an auxiliary display means 10 can be restored to the state at the time of the power source disconnection just after the power source re-supply, and a complete resume function for preventing the customer from having any feeling of distrust on a restored sales registration processing can be realized.
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