| 摘要 |
PURPOSE:To contrive to efficiently utilize the capability of a common bus by suppressing a bus request from a constitutional device with lower priority by an occupying signal and receiving an access request from a constitutional device with higher priority other than busy time. CONSTITUTION:A mutual exchanging state signal is added to divide A devices into a group of A devices 1, 2 with higher priority and a group of A devices 3, 4 with lower priority. In the group with the lower priority, the A device of the current owner sets up a newly prepared state signal during the whole period of an occupied period 'BUSY in occupied period' and suppresses an interruption in the group during the execution of an instruction. On the other hand, the BUSY signal is controlled so as not to be set up other than the practical using time of the bus by a real access. Thus, the utilizing efficiency of the bus can be improved. |
