The ETA 10 liquid-nitrogen-cooled supercomputer system

A supercomputer using CMOS circuit technology operating at liquid-nitrogen temperatures is discussed. As many as 2000 packaged circuit chips of up to 20000 gates each operate at a temperature below 90 K (which approximately doubles the speed of the circuit chips). Extensive utilization of built-in self-test provides for device and interconnect testability from the wafer at the foundry to the central processor product immersed in nitrogen. The devices are packaged and interconnected with special attention to materials choices to assure reliability of the connection structures. Laboratory cryogenic cycling studies at the device and printed-circuit-board levels are reported. Heat-transfer experiments conducted to validate nucleate boiling peak heat-flux limits of ~12 W/cm² in liquid nitrogen are described. A vacuum-jacketed cryostat vessel provides the central processor chips with their liquid-nitrogen environment and allows several thousand signal wires to connect to them with minimal heat leak. A closed-loop cryogenic refrigeration system that recondenses the gaseous nitrogen generated from the boiling heat transfer in the cryostat is described