| 摘要 |
PURPOSE:To release look-in of the program of a communication control device from the time limit and use the transmission and receiving buffer of the communication control device commonly, by providing a signal line for flow control independently of the data transmission line. CONSTITUTION:If a communicatin control device CCU1 cannot receive data during the communcation between an I/O devicde 2 and the CCU1, a signal line 5 for flow control is turned on to stop data transmission from the I/O device 2 temporarily. When the CCU1 becomes a receivable state again, the signal line 5 for flow control is turned on to start transmission of the I/O device 2 again. Consequently, a data transmission line 3 connecting the CCU1 and the I/O device 2 is controlled by the signal line 5 for flow control, and the transmission side is controlled by the state of the receiving side. |
