| 摘要 |
PURPOSE:To reduce the load of a processor, by discriminating the data transmitting or receiving operation state of a device directly in the processor to make it possible that the processor receives data independently of a storage register in a communication controller. CONSTITUTION:A communication controller 1 is provided with a transmitting state indicating terminal 11, a transmission instructing terminal 13, a receiving state indicating terminal 17, a reception instructing terminal 19, and a stop instructing terminal 21, and a controlling part 14 is connected to these terminals through holding circuits 12, 15, 18, 20, and 22. Information indicating whether the transmission is performed or not and information indicating whether the data reception is performed or not are outputted from the controlling part 14 to an upper processor 2 through terminals 11 and 17. Transmission and reception instructions from the processor 2 are received through terminals 13 and 19 by the controller 1, and the indication of the data transmission or reception signal is ignored to transmit data to the processor or receive data from the processor unless the transmission or reception is performed, and thus, the load of the processor 2 is reduced. |
