On Wed, 03 Jan 2007 05:31:01 +0100
Mxsmanic wrote:

Doug Spencer writes:

For one thing, to pass certification at level-D, your model has to be
deterministically "hard" real-time to process inputs and outputs in a
particular set time. This doesn't mean merely having a fast CPU and
memory, this means that an interrupt to the system is handled within a
known and specified time period with no overage.

Without a hard real-time response, the flight model cannot be
accurately portrayed at all times.

Not every application requires a certification of this kind.

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Transpose mxsmanic and gmail to reach me by e-mail.

Yes, but you asked for an example/reason why the flight model was
incorrect on your MSFS X simulator. I provided the reason. If your
computer is going to be non-deterministic, it cannot be an accurate
simulation.

Real, actual flying occurs in real-time. Read that previous sentence a
couple of times. If your flight model is not computed with inputs and
outputs being done in a hard real-time fashion, it is not going to be
an accurate model. If your computer will delay the processing of
your simulator's input or output because you've received a new e-mail,
it is busy processing a disk access, network request, or similar items
that occupy the resources of a computer, it is not an accurate
representation of flight.

Jay has already indicated that on his slower machine, there was a lag
in processing at various times. You will have similar lags to various,
unknown degrees on any system that is not a hard real-time system. That
is just one area where a simulation like MSFS will be incorrect. Even
on a realtime operating system, the program has to be written to
properly process tasks in realtime or it will still fail to represent
flight.

I used to play with the PC based flight simulator before taking lessons
and found it to be a very poor representation of the reality of flying.
There are far too many ways to fudge things in the simulator that just
don't work in real life.

Perhaps the group should scrape together a first flight gift
certificate for you and be done with the continued banter about things
you know little about? I expect you will find it a very different
experience than the simulator in ways you don't realize without that
experience.

Doug

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