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Path: utzoo!linus!decvax!mulga!munnari!basser!elecvax!hamish
From: hamish@elecvax.OZ (Hamish Reid)
Newsgroups: net.unix-wizards
Subject: Re: unix & real time -- is a rewritten UNIX still UNIX?
Message-ID: <421@elecvax.OZ>
Date: Thu, 22-Nov-84 22:13:09 EST
Article-I.D.: elecvax.421
Posted: Thu Nov 22 22:13:09 1984
Date-Received: Sat, 24-Nov-84 05:41:58 EST
References: <39@uwvax.UUCP>, <5633@brl-tgr.ARPA> <9785@watmath.UUCP> <5727@brl-tgr.ARPA>
Organization: EE and CS, Uni of NSW, Sydney, Australia
Lines: 40

>> > [That UNIX does not do real-time stuff well] is an old myth based partly
>> > on fact.
>> > 
>> > [List of drawbacks was here.]
>> > All these drawbacks can be overcome by a competent UNIX system programmer.
>>
>> UNIX can do anything if you just rewrite this or that.
    
>  Anyone doing real-time programming has to write some nitty-gritty stuff.
>  My point was that it is no harder to do this on UNIX than on any other
>  system (e.g., VMS). ...

...And MY point would be that for someone in my position, with a
binary Level 7 Unix License, it is actually INFINITELY harder
'to do this on UNIX than on other systems..' - eg RSX-11, on which
I can expecte and get true priority scheduling, guaranteed real-time
delays and time-outs, etc, etc... all without ANY mods to the kernel
Now RSX may be the Unix guru's idea of the canonical bad operating
system (and I'd have to agree) but our real time work simply can't
be done on any of the Unix's I have shopped around for, without
very expensive hacking at the kernel - which we can't do with
a binary license - and which is not needed with, say, RSX...
>  
>  These are hardly major changes to UNIX, ...

...again, they ARE if you have a binary license, and "support"
from your average vendor - and anyway, this just re-raises the
"what is Unix" question again - Unix will definitely SUPPORT
the DEVELOPMENT of real-time systems, which can then run on
a more supportive system (I just dream of an RSX-Unix cross
development system...), but none of the Unices available to
my organisation would support the r/t system already running
on our RSX machine.

I think it is about time people realised that MOST Unices
of the future will be binary licenses, and that to try
to make "Unix" cover all grounds is a little pointless....

Hamish Reid	...!decvax!mulga!hamish:ipso
Ionospheric Prediction Service, Sydney, Australia