FAIL-FIRST, FAIL-FUNCTIONAL AND FAULT TOLERANT MULTIPROCESSOR SYSTEM

PROBLEM TO BE SOLVED: To check the error of a processor at an interface spot without affecting the processor performance by providing a specific table means and also a means which receives a message from a peripheral device and decides whether the access should be permitted to a memory means based on the received message. SOLUTION: The routers 14A and 14B are connected to the subprocessor systems 10A and 10B, and the I/O packets 16A and 16B are connected to the routers 14A and 14B respectively. This device of such a constitution has a table means which includes plural entries to discriminate permission of the access to a part of a memory means against one of its peripheral devices. Therefore, the message packet sent via an I/O has the information on the originator and the destination. Then a receiving CPU refers to the external source that is permitted to access its memory via an access propriety check and a conversion (AVT) table and checks whether the access is permitted or not.