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Re: So... What are the alternatives? Was: I don't use an RTOS because...
On Mon, 24 Jan 2005 11:09:55 PST, snipped-for-privacy@mojaveg.iwvisp.com (Everett M. Greene)

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That may be the minimum loop time, but it's not the minimum perception time.

I suggest you imagine playing a keyboard and hearing the music that results.
When playing music .25s slop would be considered more than disastrous (I play
keyboard.)  It would be fatal.  Think about writing the software to handle an
electronic piano keyboard.  I don't think you'd never sell any with a .25s delay
in the responses.

When I use front panel keys on an instrument (and yes, I also write the software
for such instruments), 1/4 second delay between hitting a digit, let's say, and
seeing that digit appear on the display is often unacceptable to me as an
operator.  I've test this kind of delay on myself, and it was not pleasant.

Yes, I could live with it.  But I might not buy that instrument, again.

Jon

Re: So... What are the alternatives? Was: I don't use an RTOS because...
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Some years ago I built a machine on which the keystroke was applied
on the release.  This had several advantages for me - I could
positively identify the key in the midst of multiple keypushes, and
the operator could change his mind by holding the key, pushing the
correct one, releasing the key, releasing the correct one.  I was
expecting to get some harassment over the 'execute on release', but
never did.

The machine was the firstPC - see separate thread.

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Re: So... What are the alternatives? Was: I don't use an RTOS because...

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I've done that, as well.  Though one needs to think about it (or test it) before
fielding the result.  There are times when it is reasonable for the operator to
expect some kind of change on press, not release.  (Some people do kind of hold
their finger on a button for a long moment -- whether or not that is common will
depend on circumstances and people.)

Jon

Re: So... What are the alternatives? Was: I don't use an RTOS because...
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delay
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software
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The cited number was for a typical case.  Yours is for a
particular case.

Re: So... What are the alternatives? Was: I don't use an RTOS because...
On Tue, 25 Jan 2005 09:18:10 PST, snipped-for-privacy@mojaveg.iwvisp.com (Everett M. Greene)

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I don't consider 500ms good for _typical_ cases, ever.  You would usually find
me on the opposite side of the table in any discussion about a specific
instrument, if you took that point of view for it.  I've not yet met a front
panel on an instrument where I'd tolerate a 500ms delay from key hit to digit
displayed, for example.

Nor would I buy one.

But that is indeed just me.

Jon

Re: So... What are the alternatives? Was: I don't use an RTOS because...


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Ever fire a flintlock rifle? :)





I just thought of a system where 500ms is too short; hand grenade.


Re: So... What are the alternatives? Was: I don't use an RTOS because...
On Wed, 26 Jan 2005 08:35:07 +0000, Guy Macon

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No.  Sounds interesting, though.  Are they likely to use microcontrollers?  ;)

I have a hunch that if they did, and if a particular one added a .5s delay to
the triggering, and if I had a need for a flintlock for some reason and had a
choice from among some that had much shorter delays, I'd probably not select the
one with the micro offering a .5s delay.

:)

Jon

Re: So... What are the alternatives? Was: I don't use an RTOS because...
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First the flint hits the frizzen, making a spark.  The spark lights
the fine gunpowder in the pan then the fire makes it's way to the
hole and into the chamber, then the gun fires. Normal delay, 4-8ms.
Occasionally there is a "hangfire", where the gun shoots a second
or more late.  And sometimes it doesn't fire - a "flash in the pan.
Pictures here: http://members.aol.com/illinewek/faqs/locktime.htm "





Re: So... What are the alternatives? Was: I don't use an RTOS because...
On Wednesday, in article

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That depends on which response time you are looking at

        Time to start delay timing (handle release)

        Time to detonation.

The first is response to letting go, the second is the response time of
the delay function before calling the function

        void bang( void )

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Re: So... What are the alternatives? Was: I don't use an RTOS because...

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I'm curious where you got those numbers.  That seems awfully
fast.


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Cool. The timing measurements shown on that page show a 40ms
delay until the powder in the pan ignites.

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Re: So... What are the alternatives? Was: I don't use an RTOS because...

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I agree. Even a percussion muzzleloader using regular musket caps
(which I used to enjoy playing with) can take as much as half a second
to fire in normal operation. If the powder is a little damp, even
longer. It's part of the challenge of hunting with antique weapons; the
quarry can hear the snap of the priming before the main charge fires,
and it has a little time to move out of your aim.

Safety SOP for a blackpowder gun that is hanging fire is to keep it
pointed safely downrange for ONE MINUTE, then if you wish you can try
putting on another cap/refilling the pan, recocking and try again
(still keeping it pointed downrange).


Re: So... What are the alternatives? Was: I don't use an RTOS because...
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Oops. Typo. 40-80ms. :(




Re: So... What are the alternatives? Was: I don't use an RTOS because...

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Greene)
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find
front
digit

No, not just you.



Re: So... What are the alternatives? Was: I don't use an RTOS because...
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Greene)
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delay
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To this day, I still can't type on an old style IBM Selectric typewriter
because of the annoying delay between when I hit the key and the "chunk"
sound of the ball hitting the platen.

Ed


Re: So... What are the alternatives? Was: I don't use an RTOS because...

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Greene)
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time.
results.
play
handle an
.25s delay

ISTR using an old brother electric (thermal?) typewriter/word processor.  In
one
mode, the delay was in the number of characters typed, not clock time.  That
was
REALLY disquieting!  I think it caught up at the end of line.  The purpose,
of course,
was to allow you to erase a one or two character typo before it was
committed to
the page.

Rufus







Re: So... What are the alternatives? Was: I don't use an RTOS because...
On Mon, 24 Jan 2005 00:01:25 +0000, the renowned "Paul E. Bennett"

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Yes, 500ms is forever to respond to a keypress. They'll assume the key
is flakey and press it harder, multiple times and that sort of thing.


Best regards,
Spehro Pefhany
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Re: So... What are the alternatives? Was: I don't use an RTOS because...
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seconds
than

Indeed it is. When you use a serial terminal and loose 100ms or more by
sending/handshaking the commands to another piece of equipment with the
actual I/O you really need to add an audible beep or lamps locally, giving
some feedback that the key was pressed and reduce the effect of such
frustrating behaviour.

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Thanks, Frank.
(remove 'q' and 'invalid' when replying by email)




Re: So... What are the alternatives? Was: I don't use an RTOS because...

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I try to be sure that some kind of feedback response is under 80ms.  I have
debounced and recognized the keys by 24ms at the latest, though I try to shore
that up to closer to 15ms, or so.

500ms would be death.  I've used equipment where some programmer did that and I
wanted their heads on a platter.  No excuse for it.

Jon

Re: So... What are the alternatives? Was: I don't use an RTOS because...
snipped-for-privacy@amleth.demon.co.uk says...
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You can, I've run into that problem in run-time diagnostic tests watching
the closing of relay contacts.  The first test we used had a fixed amount
of delay between changing the tips and checking to see if they had opened
or closed.  Technicians of course wanted to keep that as short as
possible.  There is a significant variation from cycle to cycle and if it
was cut too short they would periodically fail diagnostics.  These were
in a direction changing application and so you would get two delays which
made the problem worse, however you could hear the relays change and
500mS was perceptibly sluggish.  I expect if responses were consistently
in the 500mS range the interface would feel laboured.

Robert

Re: So... What are the alternatives? Was: I don't use an RTOS because...

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I think they can. When one is typing quickly 500 ms can be a loooong
time. The feeling can be annoying to say the least.



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