Abstract: A multi-cluster computer system includes a plurality of clusters and a crossbar network for connecting the clusters. Each cluster includes processors, a shared memory, local network, data holding memory, shared memory access mechanism, data transfer mechanism. The data holding memory stores data to be broadcasted. The shared memory access mechanism transfers broadcast data from the shared memory to the data holding memory when one of the processors requests a broadcast. The data transfer mechanism transfers the broadcast data from the data holding mechanism to a plurality of destination clusters one after another. Each cluster may include parameter holding memory. The parameter holding memory stores parameters for each of the destination clusters. Each parameter includes information indicative of a corresponding destination cluster and an address at which the broadcast data is stored.