SYSTEM STORAGE DEVICE

PURPOSE:To realize the system storage device without requiring excess manual operations by detecting the change of a structure control register 4 and automatically resetting a required port circuit of a system storage device 10 on the system storage device shared by plural processing systems (cluster) which operate independently. CONSTITUTION:The system storage device which constitutes the SCMP system together with clusters 20a-20n is provided with plural port circuits 1a-1n connecting and controlling the clusters 20a-20n being plural independent processing systems and a structure control register 4 controlling the effectiveness and ineffectiveness of the port circuit in the unit of bit and capable of writing from an arbitrary cluster. Rising/falling detection circuits 7a-7n corresponding to the bit of the register 4 and detecting the change of the bit are provided. When the outputs of the circuits 7a-7n are '1', the corresponding port circuits 1a-1n are reset.