ChorusOS - Growing article, with links to many related topics. Wikipedia.
ChorusOS Open Source - Microkernel OS used in realtime and embedded environments. Sun Microsystems open sourced it, with 4 licenses: Sun Public License Lite, GPL, Mozilla, FreeBSD. Description, download. [ExperimentalStuff.com]
Sun Microsystems, Inc. - Makes ChorusOS: highly scalable, reliable, POSIX compliant, embedded, realtime operating system; used by top telecom suppliers, in: public switches, PBXs, access networks, cross-connect switches, voice-mail systems, cellular base stations, cell-phones, web phones.
Sun Announces ChorusOS 4.0 Software - Cornerstone for new embedded telecom platform; combines power of Solaris with realtime performance of ChorusOS. (June 8, 1999)