CRAY X² The Lost Arc

Concept R&D by Idea2Dezign™ Lab
Cray Inc., The Supercomputing Company

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By now you’re probably a bit bored of Cray computers — but the fact is, the company dominated supercomputing from its inception in the ’70s through until the early ’90s. In 1985, the Cray 2 was released. The technology used was fairly similar to the Cray 1 and Cray X-MP — ICs packed together on logic boards — and again it had a similar horseshoe-shaped chassis.

To boost performance, though, the logic boards were crammed incredibly tightly (pictured below), meaning air cooling and Freon heat exchanging was no good — instead, the the entire computer was submersed in Fluorinert. In the picture above, the device at the back is a Fluorinert “waterfall” radiator.

With increased performance (and up to 8 CPUs), Cray Research also had to overcome a memory bottleneck. Basically, the Cray 2 used “foreground” processors to load data from main memory to local memory (similar to a cache but not quite) via a very fast gigabit-per-second bus, and then pass instructions off to “background” processors which would actually perform computation. In today’s nomenclature, foreground processors would be similar to modern CPU load/store units. The peak performance of the Cray 2 was 1.9 gigaflops — about twice the Cray X-MP, and fast enough to retain the title of world’s fastest supercomputer until 1990.

The Cray 2 is notable for being the first supercomputer to run “mainstream” software, thanks to UniCOS, a Unix System V derivative with some BSD features. Until this point, Cray supercomputers had only really been used by US governmental agencies like the DoE and DoD (for nuclear modeling — what else?), but the Cray 2 found a home in many universities and corporations.