Abstract: An optical data bus communication system of an artificial satellite includes an optical transmitter, a reflection film provided over the entire inner surface of case, and an optical receiver that receives optical signals that are transmitted from the optical transmitter both directly and after reflection and diffusing by the reflection film and reproduces the optical signals from the received signals.

Abstract: In each module (11) of three or more central processor modules of a fault tolerant computer system, a detector (45) receives a comparator output signal and like comparator output signals from two adjacent modules and produces a detector output signal which confirms absence and presence of a fault in one of the above-mentioned each module. When the fault is confirmed, a controller or processor (49) isolates the module under consideration from the system by inhibiting delivery of a controlled output signal to a bus (31) and by connecting, with the module in question bypassed, switching units (53(1), 53(2)) of the adjacent modules. Preferably, one of the modules of the system is used as a master module of ordinarily delivering the controlled output signal to the bus with others used as checker modules of ordinarily inhibiting the delivery.