COMMON MEMORY ACCESS EXCLUSIVE CONTROL SYSTEM

PURPOSE:To prevent the mixture of data from both a network control section and a connection device interface section on a common memory by resetting a control signal representing the data reception from the network control section when a reply to a data reception request signal from the network control section to the connection device interface section is returned. CONSTITUTION:Packet communication equipments 1,-n having terminal equipments 1a,-na respectively are connected mutually by a communication line 100. While the data from the terminal equipment 1a is in block transfer from the connection equipment interface section 120 to the common memory 110, when the data received from the communication line 100 is written in the common memory 110 by DMA transfer from a network control section 130, a common memory control signal l40 is set. In such case, a data reception request signal 150 is informed to the connection device interface section 120 after the DMA transfer to reset the common memory control signal 140 after the data reception reply signal 160 is returned.