BUS MASTER MEDIATION CIRCUIT HAVING IMPROVED PRIORITY MEDIATION

摘要

PURPOSE: To allow a retried request have high priority through the next mediation by preventing the change in priority which is interrupted, even though access to a bus has been permitted. ;CONSTITUTION: A priority register 606 is used for mutually determining the specified priority of various masters. For this, an SNGNT [6:0] signal and a synchronization and trailing (negative) edge storage GNT signal are supplied to the priority register 606 in manner similar to RETRY MSTR and REARB signals. The specified permission is formed when all the corrected priority bits instruct the direction of that specified bus master. The output of a permission decoder 604 is a D GNT [6:0] signal to be supplied to a permission storage register 630 and a permission-off logic 632. The permission-off logic 632 receives not only PARK CPU and PCI IDLE signals but also the GNT [6:0] signal.;COPYRIGHT: (C)1995,JPO