DATA PROCESSING SYSTEM HAVING ERROR CHECKING CAPABILITY

摘要

A data processing system (10) includes a plurality of subsystems coupled via respective interface circuits (28) to a pair of transmission lines (18, 20) for carrying messages inrespective directions from and to the subsystems. The transmission lines (18, 20) are interconnected by an optical star coupler (16). The interface circuits (28) include respective error detection circuits arranged to detect errors in every transmitted message. Thus errors may be detected in a transmitted message even if the message is not intended to be received by the subsystem whose associated interface circuit (28) detects an error. For certain detected errors an ABORT signal is produced to cause the erroneous message to be garbled by the superposition of binary "1" signals. The subsystems include circuits which detect when the postamble of a message is garbled.