Re: Disobeying jet engines - why?

On Fri, 25 Jan 2008 07:02:03 -0800, John Larkin
<jjlarkin@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

On Fri, 25 Jan 2008 13:53:26 GMT, Glen Walpert <gwalpert@xxxxxxxxxx>
wrote:

On Thu, 24 Jan 2008 11:44:52 -0800, John Larkin
<jjlarkin@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

On Thu, 24 Jan 2008 13:18:35 -0600, Damon Hill
<damon1SIX1@xxxxxxxxxxxxxx> wrote:

Didi <diditgi@xxxxxxxxx> wrote in news:f121757f-1671-4ebe-892d-625ea1c236b6
@h11g2000prf.googlegroups.com:

http://news.bbc.co.uk/1/hi/england/london/7206596.stm


Anyway, to me this sounds like some popular office OS has made its
way into the cockpit and was out for lunch with the HDD while the
pilot
was trying to talk it into delivering his commands to the engine
controllers...

Windoze is NOT qualified for critical applications like this. It's
something pretty specialized and focused for the application. I
suspect the investigation will either find a hardware fault or
operator error (misconfigured autopilot). Airbus has had something
similiar happen, resulting in a crash and loss of life.

http://www.youtube.com/watch?v=-kHa3WNerjU

--Damon Real life doesn't have a 'reset' button

I know some of the guys who do the engine control computer firmware
for the Pratt&Whitney engines. They use our gear to simulate engine
sensor signals to the control computer, and run weeks/months of
scripts to verify the firmware in all sorts of situations.

Their ECC's use no OS at all, just basic bare-metal state machines.

You mean that they roll their own RTOS rather than buying one known to
work. You can make a state machine controller with FPGAs and no OS,
but a uP needs some sort of RTOS in order to function even if they
don't call it that and it is integral with the rest of the code.

I don't consider what they do to be an "OS". There is no distinct
separation between operating system and application code; no tasks are
suspended partially-done; no task contexts are saved. I'm not
absolutely sure, but I think there's no memory management and only one
stack. I'll try to find out. The guys who do this have told me,
emphatically, that there is no RTOS.

I do embedded realtime apps that have no OS. I've written a few
RTOS's, but haven't needed to use one in a long time.

If the code is...

START: do thing1
do thing2
do thing3
goto START

where is the OS?

Well you have a point, although there are not too many systems that
don't need to respond to any interrupts at any point whatsoever. And
what when thing2 fails to complete? I am not at all sure you can
write reliable code without some supervisory code that could be called
an OS. But you could call it something else and I won't argue :-).

Some of the engines run fuel through the ecc before it's burned, to
protect the ecc from temperature extremes.

John

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