| 摘要 |
PURPOSE:To exactly extract the contents of changed data neither too much nor too little by storing old data and new data in different storing means respectively, and comparing them, and extracting the new data not coinciding with the old data as the changed data, and storing only this extracted changed data. CONSTITUTION:The data generating device consists of a control device 1, and input/output device 2, a magnetic tape device 3, a magnetic tape 3a, a magnetic disk device (first storing means) 4, a magnetic disk 4a, the magnetic disk device (second storing means) 5, the magnetic disk 5a, a cassette tape device (third storing means) 6 and a cassette tape 6a. Then, data before change (old data) and the data after the change (new data) are stored in the different first and second storing means 4, 5 respectively, and those are compared, and only the data after the change which does not coincide with the old data is extracted as the changed data, and only the extracted changed data is stored in the different third storing means 6. Thus, only the changed data for the old data before the change and the new data after the change can be extracted without a mistake and in addition, neither too much nor too little. |
