| 摘要 |
PURPOSE:To inform data length information to a CPU while guaranteeing the complete transmissibility of data by storing information indicating the number of data transferred on the basis of a command specifying a command chain in a main storage device. CONSTITUTION:A flag detecting circuit 46 is connected to a data register 30, and at the end of reading of a channel command word (CCW), the validity of a program control interruption flag (PCIF) in the CCW loaded to the data register 30 is tested by the flag detecting circuit 46. When detecting that the PCIF is ''1'', the circuit 46 informs the status to a channel sequence control part 25, which stores the residual count left in a count register 34 in a CCW counting area. The data length of actually transferred data can be detected by making the program refer the area. |
