SUPER-UX was a version of the Unix operating system from NEC that is used on its SX series of supercomputers.
[4][5][6] The version for the NEC SX-9 was based on SVR4.2MP with BSD enhancements.
[4] It supports the Supercomputer File System (SFS).
[4] The Earth Simulator uses a custom OS called "ESOS" (Earth Simulator Operating System) based on SUPER-UX.
[8][9][10] It has many enhanced features custom designed for the Earth Simulator which are not in the regular SUPER-UX OS.