PosixStandard 1003.1 defines "real-time" for operating systems as: "Realtime in operating systems: the ability of the operating system to provide a required level of service in a bounded response time" See RealTime and OperatingSystem. Also see AdeOs, EcOs, InfernoOs, MenuetosOperatingSystem, PlanNineFromBellLabs (some interesting papers about Plan 9's real time implementation: http://doc.cat-v.org/plan_9/real_time/ ), QnxNeutrino, RtLinux and VxWorks. ---- I have found a site worth its weight in gold when it comes shopping for an RTOS. I haven't found any other site that has done as much conclusive testing on almost every RTOS. The WinCE 4.2 testing and a comparison to QnxOs and VxWorks is there as well. ** http://www.realtime-info.be/encyc/ -- Andrew Gardso, RTUnet Pty Ltd Thanks, Andrew. There aren't enough hardcore embedded technoweenies on this Wiki to form much of a group, so we have to share as best we can. Nice to see somebody has a handle on comparing RTOSs toe to toe. -- MartySchrader ---- IronyWarning: Don't forget WinCe -- officially called a "RealTime system" by its manufacturer. No, really. We have a project that is grounded in this concept. Stop laughing! It's RealTime, I tell you! Of course, this has required plenty of fiddling down in the BSP to make anything work that has a resolution of tighter than 100ms. Glad we're not flying missiles. From Microsoft, 10 Jun 10: ''"Windows Embedded Compact 7 is the next generation of Windows CE. Use the Compact 7 PCTP to unlock your vision for embedded devices with high performance, powerful user interfaces and a seamless connected experience to media Windows and productivity applications."'' You betcha. ---- CategoryRealTime, CategoryOperatingSystem, CategoryTime