Direct memory access control device and method in a multiprocessor system accessing local and shared memory

摘要

A direct memory access control device is used in a multiprocessor system having a plurality of digital data processors and an external common memory connected in common to those digital data processors through a first bus. In the case of transferring data in a direct memory access mode between processors, the transfer of data between the processors is effected by the control device through a second data bus provided in common to the plurality of digital data processors separately from the first bus. Thus, data can be transferred directly in a direct memory access mode between the processors without using the external memory and high-speed transfer can be realized. In addition, the control device comprises registers for storing the status bits of each digital data processor, such as direct memory access request and acceptance signals, corresponding to each digital data processor. Request and acceptance of direct memory access and transfer of data are effected by monitoring the contents of those registers.