JPS5734264A - Multiprocessor - Google Patents

Abstract

PURPOSE:To considerably reduce competition occurrence of an access to a common memory by reading data with a processing device with which writing and transfer of the data are performed for a memory corresponding to the common address are a of a transferred processing device. CONSTITUTION:Corresponding to a data writing operation from a processing device 1, a reading and writing selector 13 makes a writing bus 1(9) active, and accesses to a common memory 2(8). On the other hand, an access controlling circuit 16 in the memory 2(8) side makes, in a case where the device 2(2) has not accessed for reading of the memory 2(8), the writing bus 1(9) active, and accesses to the memory 2(8). Here, the circuit 16 makes, in a case where the device 2(2) has not accessed for reading of the memory 2(8), the bus 1(9) access, in addition, in a case where the device 2(2) has accessed to the memory 2(8), after completing a state of the access, the device 1(1) writes the data to the memory 2(8).