A cost-effective fault-tolerance control modules using concurrent write method for ATM switching system

We describe a novel duplicated fault tolerance control module using concurrent write for ATM switching system. To implement a fault-tolerance control module, we expand the bus between the main memory and memory controller that we called a memory bus. We devise a special kind of switch to implement it. In our approach, the memory is consists of CWM (concurrent-write memory) and NCM (non-concurrent-write memory). The memory controller is always accessible to NCM but is impossible to access a self-CWM in standby mode. In a duplicated operating mode, a memory controller of an active module has a responsibility for the refresh cycle of the standby memory as well as the self-side memory. When a write transaction to memory happens, it naturally reflects an other-side memory with simultaneously by a concurrent-write channel as well as a self-memory. This control module can be widely applied to a commercial system, which require a cost-effective fault tolerance control module.