"Lockheed Martin delivered a High Performance Computing (HPC)
solution to the US Navy last year to run sonar systems in nuclear
submarines. The solutions involved Apple Xserve systems using G4
processors and a Red Hat Linux-based operating system. While few
people noticed the announcements made by Terra Soft, makers of
Yellow Dog Linux, the event triggered ripples in the industry.
"The Lockheed Martin Linux systems varied in two respects from
the standard solution of the Apple Xserve. First, the solution did
not use Apple's Mac OS X operating system. Secondly, Lockheed
Martin built their own chassis and only used the internals of the
Xserve. Lockheed Martin wanted the G4 PowerPC chips and Linux to
provide a low heat, low power consumption solution. On a nuclear
submarine, such features are essential..."