| 摘要 |
PURPOSE:To certainly give the bus use right to a user device having a low priority level after a prescribed period by monitoring user devices, which cannot practically use the bus for the prescribed period, by a bus request monitor control circuit. CONSTITUTION:A bus request monitor control circuit 11 uses a control signal 011 to monitor bus request signals of user devices 20, 30, and 40 and detects user devices which cannot use a buss 051 for the prescribed time after one of bus request signals of user devices 20, 30, and 40 goes to logical '1'. As the result, a storage control circuit 13 is so instructed for the prescribed period that user devices are permitted to use the bus 051 in the order of going to logical '1' of bus request signals. This storage control circuit 13 sets bus acknowledge signals to user devices to logical '1' in the order of going to logical '1' of bus request signals. |
