EOS was the name of an operating system developed by ETA Systems (a spin-off division of Control Data Corporation) for use in their ETA10 line of supercomputers in the 1980s.EOS was preceded by and was binary executable compatible with the CDC VSOS operating system for Cyber 205. Like VSOS, EOS had demand paged virtual memory (the VS part) with 2 pages sizes for improved virtual memory performance with the ETA's faster hardware pipelines.