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Date:      Thu, 30 Mar 95 10:58:36 EST
From:      Andrew McRae <andrew@mega.com.au>
To:        hackers@FreeBSD.org
Subject:   Re: FreeBSD support for realtime systems
Message-ID:  <9503300058.AA16143@megadata.mega.com.au>

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This is starting to get off the track a bit concerning FreeBSD, but
it is of interest for people who are interested in what FreeBSD *is*
being used for around the place.

Peter da Silva writes:
>We are currently running a "soft" real time (SCADA) system on UNIX with
>realtime extensions. I haven't tried running real time on traditional UNIX.

We are running soft real time systems on SunOS, OSF/1 and HP/UX (Peter's
probably seen our MOSAIC product running) but
these are not running `hard' real time; IMHO, running real time extensions
on Unix to try to make it hard real time is trying to make a silk
purse out of a sow's ear. There are just *so* many things to change
that I question whether it is worthwhile - it's like the antique chair
that was so old I had to replace the back, the seat and three legs, but
it's still an antique :-) . I think the *real* real time stuff needs
to go into embedded (or similar) systems running something like QNX etc.,
but that Unix (or FreeBSD) does have a significant place in the rest of
the complete `real time' system. I have a saying that goes, "a few extra
MIPS covers a multitude of sins". At least with things like FreeBSD I can
*cheaply* put together a system that's fast enough to *appear* real time
without the nasty tricks.

But more specifically about FreeBSD, we are starting to install FreeBSD
as part of our Substation Management Systems, where FreeBSD can be
run on industrial PCs and be more stable and reliable than Windows.
The value of running FreeBSD is:

 - Good networking (fast, reliable, good tools etc.)

 - Multi-tasking (i.e. allow remote logins etc.)

 - Cheap! I can't fault the price :-)

 - X is available for graphical man machine interfaces.

 - It can run on a wide range of products, right from roll-your-own
   cheap PCs to industrial PCs to laptops sitting in a rack.

 - It is possible to maintain without reliance on a disinterested
   software vendor.

 - We ourselves can influence the contents of FreeBSD by creating
   our own schedulers and changes to make it more responsive.

There is probably no reason why our mainstream `big' product
can't be ported to FreeBSD - someone ported it to Linux, but
ran into networking problems - FreeBSD would be a much more
natural system for it to be ported to.

The point is that I think FreeBSD can be a major win for
niche software developers like ourselves (I said `niche' not `nice' :-)

Cheers,
Andrew McRae			inet:	andrew@mega.com.au
MITS Real Time Ltd,		uucp:	..!uunet!mega.com.au!andrew
North Ryde  2113		Phone:	+61 2 805 0899
NSW    AUSTRALIA		Fax:	+61 2 887 4847



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