Embedded Configurable operating system (spelled eCos) is an embedded RealTimeOperatingSystem.  Originally from Cygnus, then RedHat [http://sources.redhat.com/ecos/ ]
** http://www.ecoscentric.com/.

It is free, covered by something GPLish. It is much lighter than embedded linux, even UcLinux.  Comparable to RtLinux. It seems to mainly be eating into VxWorks' area, but I'm not sure.

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See EmbeddedSystem.
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CategoryOperatingSystem