Hi, Peter.

PH>patient monitors for the ICU, ...opening the bomb bay doors on the F-22,
PH>... injection molding machine controls...."  I consider this proof that
PH>it is possible (at some level of response) to do real-time under OS/2,
PH>but it (a) won't be easy learning how, and (b) won't achieve the same
PH>performance as a dedicated system or custom RT kernel.  Even Steve
PH>couldn't directly answer my query as to whether or not OS/2 could
PH>support my need for closed-loop control operating at around 2000 inner
PH>loop iterations per second with low jitter (250 microsecs tops).

Thanks for including this information, Peter.  This is part of what I
was angling for (a) above.  The level of support via the docs, IBM
support techs, etc., for RT under OS/2.

If I understand you correctly, and if my math is accurate, 2000
iteration loop would be "sampling" once every (1,000 ms/2000
iterations=) .5 millisecs/iteration, right?

My understanding is that a 486/33MHz has a MIP rate of about 20 - 30 -
that is, about (at the lower range) about 20 million instructions per
second or 20,000 instructions(on average) per millisec; or about 10,000
instructions per .5 ms.

Is this what you mean?  That you could not process what you need to
process in about 10,000 instructions on this size machine?

I am not sure what you mean by "jitter".  Could you please explain.  I
would like to understand.


PH>LR>Big warning bells are now going off in my brain for this
PH>LR>project    thanks to you.  You are affirming my fears.

PH>PH>At the very least your client is out to lunch in wanting to run
PH>VxWorks "on top of" OS/2 (or under it, or beside it...).  If
PH>Craig's description of the product is correct, and I'm sure it is,
PH>VxWorks is as much an operating system as OS/2 and you simply
PH>cannot run the two of them simultaneously.

Seems to make sense but based on what job spec, I wasn't sure what
the client may have intended. I had to ask and hope someone with
specifc experience could make better sense of these vague specs.  :)

I don't think Craig was implying VxWorks is "as much" and os as OS/2.
From his description it clearly is not.  As I understand it, it is
simply a dedicated RT os (monitor?).

If I understood what Craig said, VxWorks runs stand alone.  That
eliminates, I think,  several possible combinations - VxWorks on top of
OS/2 or under it.

What I am about to ask Craig is how one *builds* a RT apps so it will
run under VxWorks. I am trying to determine if perhaps UNIX and/or OS/2
is used as the development and *test* platform for building the VxWorks
apps.

PH>I have a little
PH>real-time kernel for DOS that manages to run under OS/2's DOS
PH>emulation without crashing (a tribute to either my or IBM's
PH>programming :-), but it sure as TI invented the transistor doesn't
PH>have real-time performance that way! I lost an order of magnitude
PH>in performance trying this out on a lark.

That is interesting.  It seems to leave open the possibility of doing
some RT emulation under OS/2.  What (OS/2) priority did you run your RT
under?


PH>LR> I am not sure how you concluded it is not a OS/2 related issue?
PH>  :
PH>Sorry, I forgot that the client thought VxWorks and OS/2 had some
PH>relation.  They almost certainly don't, but as you thought they did at
PH>the time, you were certainly justified in posting here.  Make sure you
PH>read Craig S.'s message and you can form your own opinion.

PH> OS/2 jobs are whenever I can convince the customer, and when it's
PH>appropriate.  This means none to date. :-(

I am not seeing much demand for (external) consultants to work on OS/2
projects - nor high enough rates on the few I do hear about (thru
Technical Service Firms or Consulting firms) to motivate me - not yet.

PH>I am waiting anxiously for the next release of OS/2 to run in the 4MB
PH>machines in a test lab with which I work closely.  Roughly around the
PH>time it is released, I will have obtained some initial results related
PH>to porting my test applications to OS/2.  If the results are favourable,
PH>this lab will be my first big (4 machines initial, 7 eventual) OS/2
PH>installation for real-time purposes.

I would be much interested in hearing the results.


PH>LR> Would you be interested in hearing about software engineering jobs
PH>LR> here in the USA?
PH>  :
PH>Always interested in any such info, provided they are not permanent
PH>positions.

PH>however, or maybe in F-Consulting (where I know you also visit).

Can you send and receive Netmail - that seems to make more sense.  Not
too many software types (contractors/consultants) like us there as far
as I can determine and I find the disussions of limited value to my
business interests there.

As you may already have noted, some of the msgs I get in F-Consulting
leave much to be desired. It seems that some people can not clearly
understand what I clearly state - nor participate in *rationale*
discourse. But make up your own mind on that.  :)

I will try to send you a Netmail msg (on jobs) today.  Let me know if
you get it, OK?

Regards, -= Lou =-


--- WM v3.10/91-0154