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From: Gary Scott <Gary.L.Scott@lmtas.lmco.com>
Newsgroups: comp.lang.ada
Subject: Re: ADA os talk
Date: Tue, 28 Aug 2001 09:29:44 -0500
Organization: LM Aeronautics
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Date: 2001-08-28T09:29:44-05:00
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Hi,

Larry Kilgallen wrote:
> 
> In article <9me6q4$aai1@news.cis.okstate.edu>, David Starner <dvdeug@x8b4e53cd.dhcp.okstate.edu> writes:
> > On Mon, 27 Aug 2001 10:44:35 -0400, Marin David Condic <dont.bother.mcondic.auntie.spam@[> wrote:
> >> Make
> >> sure that it can handle a variety of scheduling algorithms so that it might
> >> be made suitable for realtime or non-realtime programming.
> >
> > Are there any good examples of desktop OS's with good realtime
> > capabilities? Hybrids always show favortism towards one side or the
> > other, sometimes to the point of unusability to the stepchild.
> 
> I would say VMS is a good example, if you agree that:
> 
>         Just because there are a lot of applications that are
>         missing from the GUI interface, that does not mean
>         there is a technical (as distinguished from marketing)
>         limit preventing their presence.
> 
>         You cannot really get the GUI performance you have come
>         to expect while realtime processes are running.
> 
> You do have to set process priorities appropriately, and of
> course the definiton of realtime is that events are handled
> within some predictable timeframe.  Certainly someone can
> define their timeframe requirements tighter than VMS can
> handle, but they could also define those requirements
> tighter than can be handled by the hardware -- any hardware.

Actually, this was such a limitation of VMS back in around 1981, that it
caused us to discount VAX/VMS in favor of Harris mini's and VOS.  We
still have about 6 of them (H1200) in use today.  We had a competitor
try to duplicate our system on VAXs once.  They ended up using 4 VAX
11/780s to our one H800 (1 H800 = approx. 1 11/780 in terms of MIPS).