DMA access arbitration device in which CPU can arbitrate on behalf of attachment having no arbiter

摘要

In a computer system having both peripherals having their own DMA channel arbiter and peripherals having no arbiter, a separate arbitration unit, controlled directly by the CPU, is provided to arbitrate on behalf of peripherals having no arbiter. The CPU can thus freely assign different arbitration levels to such peripherals, and can instruct the arbitration unit to simultaneously arbitrate on different arbitration levels or for two or more DMA channels.