An evaluation system has been developed to address the system level considerations for fiber optic data buses. The system was used to evaluate an autonomous access protocol and an optical data bus receiver. The protocol was shown to function with virtually no data collisions when received signals are above a sensitivity level of minus 46 dbm. The optical receiver was demonstrated to accomodate an optical signal range of 23. 0 db when transmissions are separated by at least four bit periods. Thus, a practical 1. 0 Mb/s fiber optic data bus has been demonstrated to be realizable with existing technology.