Date: Wed, 6 Jan 1999 11:40:15 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender: eliz AT is
To: Eric Rudd <rudd AT cyberoptics DOT com>
cc: djgpp AT delorie DOT com
Subject: Re: timing in u sec range
In-Reply-To: <36928BD8.8FED643D@cyberoptics.com>
Message-ID: <Pine.SUN.3.91.990106113953.8103R-100000@is>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Reply-To: djgpp AT delorie DOT com


On Tue, 5 Jan 1999, Eric Rudd wrote:

> Under DOS, uclock() seems to work fine.  Unfortunately, under Win95 uclock()
> exhibits errors on the 55-ms level, which I have been unable to completely
> diagnose.  I sometimes even get *negative* times for events.

This is a known problem.  `uclock' reprograms the timer chip to use a
different mode, since the default mode makes it hard, if not
impossible, to get consistent results.  It seems that Windows 9X
sometimes reprograms the timer back.

You could use the VTD VxD to get accurate times on Windows 9X.  I
think somebody posted the code to do that a while ago.