High-speed external memory system

摘要

In an external memory system having a program mode for controlling a read/write operation of a memory of the external memory system by a central processing unit and having a direct memory access mode permitting a direct access to a main memory, there are provided first and second location address registers. The memory addressing is performed by the first location address register in the direct memory access mode and by the second location address register in the program mode, whereby it is possible to execute the read/write operation with the memory of the external memory system in the program mode during a burst timing interval during data transfer in the direct memory access mode, thus permitting high-efficiency data processing.