From:	fx DOT maletras AT kingston DOT ac DOT uk
Newsgroups:	comp.os.msdos.djgpp
Subject:	PC-based instrumentation problem
Date:	Mon, 07 Aug 2000 12:32:36 +0100
Organization:	Kingston University
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

Hello all

I know I am a bit off-topic but still I am sure you must know something
about
what's happening :

I wrote a simple program in TC++ for DOS that  performs a signal
acquistion.
It's based on a 8253 timer that interrupts the CPU ( 486 dx4 ) at  fixed

time intervalls (the sampling period) to call an ISR that performs the
acquistion by controlling an AD card. Classic...

It works perfectly OK in DOS 7.0 but when I try to run it from
Windows95, the ISR timimg is not accurate ie my sampling period is not
constant and
of course that leads to sampling error which makes my application
unreliable. (I mean it works but it's not as accurate as it should be)
Modifications of the  DOS window parameters do not seem to produce any
improvement whatsoever.

So :
Why is W95 so messy with the timing of my ISR ?
Can I do anything to correct that ?
Is it worth trying  a better OS ?
Do you think recompiling my code with a Windows C++ compiler
would make a difference ?

Cheers
FX

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