Newsgroups: comp.realtime,comp.os.qnx,comp.os.ms-windows.advocacy,comp.robotics
Path: cantaloupe.srv.cs.cmu.edu!das-news2.harvard.edu!news2.near.net!news.mathworks.com!yeshua.marcam.com!charnel.ecst.csuchico.edu!csusac!csus.edu!netcom.com!jfox
From: jfox@netcom.com (Jeff Fox)
Subject: Re: Real-time systems:  Windows-NT or QNX
Message-ID: <jfoxCxu0tH.1zs@netcom.com>
Sender: jfox@netcom.com (Jeff Fox)
Organization: Netcom Online Communications Services (408-241-9760 login: guest)
Date: Mon, 17 Oct 1994 19:29:41 GMT
Lines: 33
Xref: glinda.oz.cs.cmu.edu comp.realtime:7202 comp.os.qnx:2256 comp.os.ms-windows.advocacy:40699 comp.robotics:14473

On Fri, 14 Oct 1994 00:23:09 GMT, bernie@ecr.mu.OZ.AU (Bernie Kirby) said:
>
> The intended application for the robot is hazardous and if the
> software failed the potential for disaster is great. I know we
> have to take responsibility for our own bugs but which systems
> is more reliable or robust. Is there any type of certification
> for computer systems that must run in hazardous
> environments. Does either windows NT or QNX have such
> certification. Failing that, it would be nice to know which
>

The ability to certify or verify the bug free nature of your intended
application is roughly proportional to its complexity.  The complexity
of your application is roughly equal to the number of instructions on
this choosen platform raised to the power of the total number of
instructions in your application and the OS on top of which you build
your application.

When you choose to use to use an OS 1000 times larger than you may
need lots of things happen.  Hardware will cost more.  Software
development will cost more.  Performance may drop from  1us task
switches to 500us task switches.  The reduction in performance will
drive up required resources, and development costs even more. AND
your application will become n^1000 times more complex and difficult
to maintain!  In other  words it will IMPOSSIBLE to certify as
correct and bug free in the real world.  

I you choose this course then find and insurance company that does
not understand anything about software complexity and get LOTS of
disaster insurance.

Jeff Fox
Ultra Technology
