PRECISE TIMING ON IBM PC/AT COMPATIBLE

[Leonard J. Trejo]

Say, we're trying to measure human reaction times (<1ms) by timing the
interval between a video field and a keypress (on the keyboard) on 
our PC-compatible (Compaq 386/25) using the C subroutine call 
"ftime()", which purports to provide millisecond accuracy (MSC 
5.1).  Some net-news discussions I've followed say that the 
precision of ftime() may actually be _worse_ than 1 ms (say 8 ms), 
even though the time returned is measured in ms.  So, I thought I'd 
ask to see how others accurately measure intervals on PC's.  Would 
you be kind enough to send me a short description of how you do it 
and/or some example programs?

			L. J. T.

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