| 摘要 |
Special control within a data processing system is signalled by a predetermined unique combination of data and error correcting code (ECC) bits. The predetermined combination, received from a source (1), is one which normally is decoded to indicate the presence of an uncorrectable error. A comparator (3) compares data bits held in a register (5) with a reference pattern of data bits held in a storage medium (7). At the same time, a syndrome generator (9) generates a syndrome from the received word, which syndrome is decoded by a syndrome decoder (11). If a particular flag syndrome sf (which is selected from the syndromes normally indicating the existence of an uncorrectable error) is detected, and comparator (3) indicates an equal comparison, AND (13) will provide a signal indicating that the unique combination has been received. It will also, through inverter (15) and AND (17) block transmission of an error indication to the system. |
