A system architecture called “2 out of 3 computers” fault tolerant, in use in specific rail applications, operating with 3 computers in Normal mode with Watchdog fail safe; as soon as this “sees” a difference between the three computers, excludes what different, and the system enters a reserve mode, continuing the service. A maintainer will repair it without service interruption. Besides the computer, there are various memory cards and I / O and other duplicate components
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