physical memory (256 MWord) than all previously delivered Cray machines combined. Simulation moved from a 2-D realm or coarse 3-D to a finer 3-D realm because computation did not have to rely on slow virtual memory. Uses and successors The Cray-2 was predominantly developed for the United States Departments of Defense and Energy. Uses tended to be for nuclear weapons research or oceanographic (sonar) development. However, the first Cray-2 (serial number 1) was used at the National Magnetic Fusion Energy Computer Center at Lawrence Livermore National Laboratory for unclassified energy research. It also found its way into civil agencies (such as NASA Ames Research Center), universities, and corporations worldwide. For example, Ford and General Motors both used the Cray-2 for processing complex Finite Element Analysis models of car bodyshells, and for performing virtual crash testing of bodyshell components prior to production. The Cray-2 would have been superseded by the Cray-3, but due to development problems only a single Cray-3 was built and it was never paid for. The spiritual descendant of the Cray-2 is the Cray X1, offered by Cray. Comparison to later computers In 2012, Piotr Luszczek (a former doctoral student of Jack Dongarra), presented results showing that an iPad 2 matched the historical performance of the Cray-2 on an embedded LINPACK benchmark. Trivia Due to the use of liquid cooling, the Cray-2 was given the nickname "Bubbles", and common jokes around the computer made reference to this unique system. Gags included "No Fishing" signs, cardboard depictions of the Loch Ness Monster rising out of the heat exchanger tank, plastic fish inside the exchanger, etc. The power consumption of the Cray-2 was 150–200 kW. Research conducted at the Lawrence Livermore National Laboratory in the early 1990s indicated that to a limited extent the perfluorinated polyether used to cool Cray-2 circuits would break down to form the extremely toxic gas perfluoroisobutylene. At the time, Cray had created a poster showing the transparent "bubble chamber" that the cooling fluid was run through for visual effect, with a spill of the same material glistening on the floor—the joke was that if this actually occurred, the facility would have to be evacuated. The manufacturer of the liquid developed a scrubber that could be placed in line with the pump that would catalytically degrade this toxic breakdown product. Each vertical stack of logic modules sat above a stack of power modules which powered 5