RE: [CAD_CAM_EDM_DRO] What about QNX?

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>From: Randy Gordon-Gilmore [mailto:zephyrus@...]
>I don't know too much about operating systems (I'm a mechanical guy), but
>the talk about realtime leads me to ask, "What about QNX?" It's billed as
>a realtime equivalent for Linux and Unix, and is free for downloading at
>http://www.qnx.com The only reason I know about it is because it came
>preloaded on my i-opener once-web-appliance-but-now-flatscreen-PC :-) The
>FAQ on their site says that most programs written for Linux should also
>work under QNX.

I was planning to look into this, in my ample (hah!) spare time. If I recall
correctly the QNX kernel is a descendant of the one for the Thoth operating
system, which we used yea long ago in our real-time programming course at U of
Waterloo (at the time the task was to run model trains on a track layout using a
DataGeneral NOVA minicomputer).
We recently downloaded the QNX package and had a quick look at it. I don't
remember the exact timing figures they quote, but it seems to me that they were
in the ballpark of 2 microseconds of interrupt latency (interval between
transition on the interrupt line and the start of the first instruction of the
handler), and a similar figure to schedule a regular process if there's too much
work to do at the handler level.
If this is indeed based on the Thoth kernel, a lot of the messaging that takes
place between modules in EMC might be converted into the OS-level messaging
calls. Might have to butcher the EMC source to do it, though... Of course, EMC
might be directly useable too.
-Kevin Martin