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vrf current test

Question asked by VRFuser on Jun 9, 1999
All ISA (IBM PC/AT and compatible) computer systems generate a hardware
interrupt on IRQ0 18.2 Hz. This interrupt is mapped to INT 8 and can be
intercepted by any application that wants to hook it. At 18.2 Hz, the
interrupt occurs approximately once every 55 ms. The Windows system driver
hooks INT 8 and maintains the value returned by the GetTickCount function.
Thus, this value is accurate only to within 55 ms.

Get one of those ActiveX timer controls. I downloaded one from but have never found the time to try
it out. Supposedly this will do what you need.

-----Original Message-----
From: Alfred Holmberg []
Sent: Thursday, June 10, 1999 2:32 AM
Subject: RE: Need help. Millisecond timing

I have rougly the same problem. I want to calculate events per second.

Present I read two event counters at about 1 sec. intervals and divide on
time interval using successive "now()" readings. I use 5.01  version under
Win95, and have also noticed the 10 ms resolution.

But to obtain neccessary accuracy I need 2 ms resolution or better. So I
would be very grateful for any suggestions on how to come around this
problem, if possible without resorting to additional external electronics.

I have noticed that the "Tmer" has split millisecond resolution,  but can
its accuracy be trusted ?


Alfred Holmberg
Norske Skog ASA
7620 SKOGN