This paper describes the architecture,fundamental principle and implementation of a distributedfault-tolerant system——DFTSNA.Its objective is to combine extreme reliability with high availability in ashipboard environment.Multi-level fault tolerance is considered and several special-purpose hardwaresubsystems(F-T clusters)are developed.The physical and functional distribution of the system is empha-sized to meet the stringent shipboard requirements.A number of algorithms are produced to supportfault-tolerant operation. This paper describes the architecture, fundamental principle and implementation of a distributed fault-tolerant system - DFTSNA.Its objective is to combine extreme reliability with high availability in ashipboard environment. Multi-level fault tolerance is considered and several special-purpose hardware subsystems (FT clusters ) are developed. The physical and functional distribution of the system is empha-sized to meet the stringent shipboard requirements. A number of algorithms are produced to supportfault-tolerant operation.