A system and method, employing a data storage device, for providing communication between a plurality of processing units which are respectively unconnected to each other, with the processing units each separately coupled to the data storage device. A data storage device controller coupled to storage interfaces and to a buffer, recognizes "broadcast" commands and any message accompanying the "broadcast" commands, and recognizes "read message" commands, received from the processing units. The controller stores the message accompanying the "broadcast" command in the buffer, and forwards, at the storage interfaces, a "message ready" signal to at least one of the processing units. The processing units then send a "read message" command to the data storage device. The controller responds to a "read message" command at one of the storage interfaces, supplying the message stored in the buffer at the storage interface to the sending processing unit.