The RDT Router Chip: A versatile router for supporting a distributed shared memory

JUMP-1 is currently under development by seven Japanese universities to establish techniques for building an e cient distributed shared memory on a massively parallel processor. It provides a coherent cache with reduced hierarchical bit-map directory scheme to achieve cost e ective and high performance management. Messages for coherent cache are transferred through a fat tree on the RDT(Recursive Diagonal Torus) interconnection network. RDT router supports versatile functions including multicast and acknowledge combining for the reduced hierarchical bit-map directory scheme. By using 0.5 BiCMOS SOG technology, it can transfer all packets synchronized with a unique CPU clock(50MHz). Long coaxial cables(4m at maximum) are directly driven with the ECL interface of this chip. Using the dual port RAM, packet bu ers allow to push and pull a it of the packet simultaneously. key words: router, interconnection network, cache coherent distributed shared memory