The data processing system with direct memory access control and process for the bus master change using gaps with a given priority

摘要

A data processing system having a direct memory access controller (DMAC) which can be interrupted with a prioritized signal to vary bus mastership of a communication bus in the system. A prioritized interrupt signal is sent to a CPU when the DMAC has bus mastership. The CPU only informs the DMAC of the highest priority cumulative interrupt priority. With the use of a mask value, the interrupt may be selectively screened by the DMAC so that selective interrupts may remove bus mastership from the DMAC.