| 摘要 |
PURPOSE:To check an illegal result due to defective software before a final output and to improve the reliability of a system by concurrently running a variety of software independently developed so as to obtain specifications ensuring an output including the same contents as those of an input and checking whether each output can be the same at every transaction. CONSTITUTION:A dual system A is made of hardware, an OS and a user program (UPA) in the same specifications. Among them the copied OS and USA are used. Separate from the system A, a dual system B is made of a UPB which has the same specifications as those of the UPA but is independently developed, hardware in the same specifications, and the copied OS of the dual system A. The dual systems A and B check hardware. The results that the both dual systems recognize as abnormality are compared (software checking), and the only results with the same contents are outputted. |
