| 摘要 |
PURPOSE:To avoid an overlook of the service-out or the data-out that is caused by an input/output device, by installing a means to store the service-in signal and the data-in signal and thus always securing a time duration larger than the prescribed value for both signals. CONSTITUTION:When the service-in signal SVI is sent from the input/output controller IOC, the channel CH stores the signal SVI as far as no data-in signal DTI is stored and turns the signal SVIM to 1. Then the service-out signal SVO is sent to the IOC from the CH when a permission is given to the writing of data into the buffer in the case of the input and when the data is put on the bus-out line in the case of the output. If the signal SVO is dropped, the signal SVIM is also dropped. Thus the signal DTI is stored, and the signal DTIM is turned to 1. Then the signal DTO is transmitted to the IOC from the CH when the same condition is satisfied as the transmission of the signal SVO. As a result, the time duration is always larger than the prescribed value for both signals SVO and DTO. |
