| 摘要 |
PURPOSE:To always obtain the coincidence between a main file and a backup file by providing a pair of file memories to write data to both files and to read the data out of one of both files. CONSTITUTION:POS terminals 11-13 are connected in a loop to a file controller 14 via a transmission circuit line 15. The 1st and 2nd file memories 16 and 17 are connected to the controller 14 and used as a main memory and a backup memory respectively. The data of the same contents are written to both file memories; while a reading command is given only to the memory 16 for reading the data. Thus it is possible to always have the coincidence of contents between both file memories. This facilitates an easy data control even in a backup mode of files. |
