| 摘要 |
PURPOSE:To simplify an access control circuit by extending bus using permission by a waiting signal from a waiting control circuit when an access to a hardware unit other than a unit group is requested. CONSTITUTION:The unit groups 1-N are connected to a bus A. Each of the unit groups 1-N is constituted of a lower bus B, units 11-1M connected to the lower bus B, an access control circuit D, and a bus control circuit E. The bus control circuit E responds to the using requests from the respective units 11-1M to the bus B in accordance with the previously fixed priority, supplies using permission to the units 11 1M, and when the bus using request indicates the access to a hardware unit other than the unit groups, extends the bus using permission in accordance with an output of the waiting control circuit outputting a waiting signal. The waiting signal is ended in interlocking with the execution of the access.
|
