Editing Cray-1 (section)

===Performance===
In 1978, a team from the [[Argonne National Laboratory]] tested a variety of typical workloads on a Cray-1 as part of a proposal to purchase one for their use, replacing their [[IBM System/370|IBM 370/195]]. They also planned on testing on the [[CDC STAR-100]] and [[Burroughs Scientific Computer]], but such tests, if they were performed, were not published. The tests were run on the Cray-1 at the [[National Center for Atmospheric Research]] (NCAR) in [[Boulder, Colorado]]. The only other Cray available at the time was the one at Los Alamos, but accessing this machine required [[Q clearance]].<ref name=eval>{{cite tech report |first1=Larry |last1=Rudsinski |first2=Gail |last2=Pieper |title=Evaluating Computer Performance on the Cray-1 |date=January 1979 |publisher=Argonne National Laboratory |url=https://inis.iaea.org/collection/NCLCollectionStore/_Public/11/523/11523500.pdf}}</ref>

The tests were reported in two ways. The first was a minimum conversion needed to get the program running without errors, but making no attempt to take advantage of the Cray's vectorization. The second included a moderate set of updates to the code, often unwinding loops so they could be vectorized. Generally, the minimal conversions ran roughly the same speed as the 370 to about 2 times its performance (mostly due to a larger exponent range on the Cray), but vectorization led to further increases between 2.5 and 10 times. In one example program, which performed an internal [[fast Fourier transform]], performance improved from the IBM's 47 milliseconds to 3.<ref name=eval/>