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From: Robert Love <rlove@neosoft.com>
Subject: Re: Ada and ISS
Date: 2000/10/18
Date: 2000-10-18T00:00:00+00:00	[thread overview]
Message-ID: <60DBAE83940C03E7.BF244DC5EE3E5B00.9935FCDD8D0050E9@lp.airnews.net> (raw)
In-Reply-To: 8sb5b0$jo3$1@nnrp1.deja.com

>>>>> "David" == David Michaels <free08@my-deja.com> writes:

    David> Hi Can someone please direct me to a link or a web page
    David> that might describe Ada's use in the International Space
    David> Station. I haven't seen much so far so I figure that I'm

Web pages on this subject are kind of rare but let me try summarizing.

The software that runs on ISS is distributed thru a 3 tiered network
of computers called MDM's.  They communicate with each other and the
devices they control via 1553 protocol. The software that resides in
these MDMs is written in Ada, almost exclusively.  There is one case,
the Guidance and Nav (GNC) MDMs, written in Ada but designed in a tool
called MatrixX.  Here the designer draws block diagrams of control
algorithms and the program writes the Ada that gets compiled.  Its not
pretty.  In the case of the other MDMs, the code is written by people
and is "human readable".  In all cases I know of, Boeing has written
the software for the MDMs in three locations, Houston, Huntsville and
Huntington Beach.

Now, many of the devices commanded by the MDMs have some type of
firmware controller residing in them.  The ones I'm familiar with were
written in C.  Also used on the Space Station are a series of laptop
computers called PCS that the crew use to interact with the MDMs.
These run Solaris operating system, run X-Windows for displays and are
programmed in C or C++.  As an aside, I recently heard of a laptop
problem where the display for one instrument was not being called up.
Seems the programmer had overloaded some C++ function but at runtime
it was ambiguous what should really be called and it picked the top
entry off of the table which was not the correct function.

Mission Control (MCC) can also command most of the operations on the
station from Houston.  I believe most of the MCC stuff is in C.  There
is a large contingent that wants to go to all C++.

Another large segment devoted to Space Station are the simulators.
There are both part task trainers(PTT) and the full task trainer
(FTT).  The latter is a full up simulator with cockpit mockups and is
used to train both the flight crew and the mission controllers.  The
PTT and FTT are written in Ada by Raytheon in Houston.  Only a very
small portion of the code is in C or assembler.

So, while Ada plays the dominant role in software that goes into orbit
on Station it is by no means the sole player, or even a popular one.
The cry to switch to C++ is heard often.

During the assembly ops that happened Saturday I happened to be
monitoring an audio loop from Mission Control where a "controller" was
conducting part of a formal procedure.  The device being commanded had
a minor glitch and I heard one controller ask another what language
the device had been programmed in.  The answer was C and when the
controller who asked the question got the answer he started off about
how C++ was a way to "organize the code".  These are not programmers
but people who work in space operations.  But they have acquired the
mindset that everything should be in C++.  That attitude seems
prevalent in all aerospace arenas today.  How did we get there?

-- 
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      parent reply	other threads:[~2000-10-18  0:00 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2000-10-15  2:38 Ada and ISS David Michaels
2000-10-15  0:00 ` Robert Dewar
2000-10-16  0:00 ` Jerry Petrey
2000-10-18  0:00 ` Robert Love [this message]
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