| 摘要 |
<p>A prior art microcomputer system can be arranged for performing direct memory access operations controlled by special circuitry that is separate from the main processor arrangement. In the main processor there is circuitry which generates addresses for use in processing routine instructions. A direct memory access controller has separate circuits which generate addresses for the direct memory access operation. Thus duplicate address generating circuits are used in the prior art microcomputer arranged for direct memory access. Such duplication of circuits requires extra chip area which increases the cost of the microcomputer. This problem is overcome by the disclosed microcomputer system having direct memory access circuitry (85) included on a single chip with the main processor (27, 30, 32, 70, 96) of the microcomputer. Addressing for direct memory access operations is accomplished by circuitry (60, 66, 78, 99, 102) also used for generating addresses when processing routine instructions in the main processor (27, 30, 32, 70, 96). </p> |
