PURPOSE:To simplify a bus interface control circuit and to avoid a delay of a reply cycle time by defining a state of a bus of a status code signal to be 'no answer' when each receiver gives no reply. CONSTITUTION:ID information received by a receiver side bus interface control circuit (BIC) 4 is set to an ID register 8 and its output 8-2 and an output 7-2 of an ID register 7 specific to a receiver are compared by a comparator circuit 9. When the result of comparison is dissident, a driver 17 becomes a high impedance state and the content of an ST register 12 is not outputted to a status code bus 1-3. When the bus 1-3 is not driven from any receiver side BIC 4, the content of the register 13 is referenced from other circuit section of the BIC 4 via a receiver 18 and a status code of 'no answer' is detected, Thus, no bus cycle delay up to the reception of a status code is caused and the bus control circuit of each receiver is formed with the same operation logic and simplified.
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