| 摘要 |
PURPOSE:To use efficiently a common bus by insuring the next activation against applying unless a channel controller receives an activation termination report from an I/O device of low priority. CONSTITUTION:The channel controller CC applies periodically activation to the I/O device having an activation request. A period T (T') is variable. Unless a device (I06) of the lowest using priority of the common bus CB terminates its activation, the next activation (initial triangular mark of the period T') will not apply. The channel controller CC monitors the activation termination report of each device by a certain period (t) to prevent such a device that leaves the common bus CB unused by one activation cycle. While the I/O device of low priority is using the common bus CB or waiting it, the activation of the high priority device is inhibited. |
