Abstract: A method of data transmission for a loop-linked processor system enabling an easy access to the internal memories of the processors which are normally not directly accessible from the data transmission loop. The method includes the steps of reserving one portion of each common memory for a command signal from one processor commanding to bring data in the internal memory of another processor to the common memory of the corresponding transmission controller: bringing data in the internal memory of one of the processors to the common memory of the corresponding transmission controller, only when the command signal from another processor is received; and reserving another portion of each common memory for those data originally in the internal memory of one processor which has been brought to the common memory of the corresponding transmission controller.