The work is devoted to the reliability of non-recoverable two-channel automation systems and computer equipment. As alternative options, a system with block duplication (SBD) and a system with a quasi-bridge structure (QBS) are considered. SBD in general is a two-channel system consisting of a series connection of duplicated nodes of different reliability. In case of failure of one of the functional subunits (FSU) of the duplicated node using the control and reconfiguration (SCR) scheme, it is

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... asked, withdrawn from the computational process, and reconfigured the system structure in the "Non Stop" operating mode. A QBS system also represents a two-channel structure, but consisting of a serial connection of duplicated nodes of equal reliability, while the technical element intensity (redundancy level) and the functionality of this system are identical to SPD. The QBS system is also a fail-safe system that provides the "Non Stop" mode of operation. The probabilistic-physical calculation method (WF-method) is used as a tool for studying the reliability of systems, which is based on the diffusion distribution of mean-time-to-failure (DN-distribution), specially formalized for assessing the reliability of electronic, electrical and electromechanical elements and systems. While maintaining the redundancy level of the considered two-channel redundant systems, decomposing the channels into equally reliable duplicated nodes leads to the R-effect – an increase in the likelihood of system uptime with an increase in the number of nodes. The presence of the R-effect was established by other methods of calculation and by statistical modeling for both non-restored and restored systems.