| 摘要 |
PURPOSE:To prevent the use of a bus due to fruitless bus transfer in read modify write RMW operation by displaying the continuation of the RMW operation. CONSTITUTION:When a data processor generates a request to use the bus including the RMW operation and a bus controller accepts the right to use the bus, a signal BSBUSY is held at a level L. Then, a main storage device is informed by a signal BSWRIT that reading operation is in process, and a signal BSRMW signal is held at the level L because of the RMW operation to transfer an address to the main storage device together with a signal BSDVLD. The main storage device holds a signal BSACEP signal at the level L to respond to the signal BSDVLD and also holds a signal BSLOCK to indicate that the RMW operation is carried out. Consequently, the use of the bus due to fruitless bus transfer in the RMW operation is prevented. |
