Craig,
This is a great description. I don't know enough (yet) to make any claims
but I believe that a properly written VxD would enable the same job to be
done under Windoze. There would be a lot of advanges to having a Windows
based program if you could get the timing part down. I don't interface to an
external timer because there are already options available, and I see having
the PC do timing as the "nitch" for Accucros.
Gary
Gary Poole
GPSoftware
P.O. Box 421
Liberty Lake, WA 99019
Phone/Fax (509)532-1702
E-Mail: gpsoftware@icehouse.net
Web: www.icehouse.net/gpsoftware
-----Original Message-----
From: Craig Blome <cblome@yahoo.com>
To: GPSoftware <gpsoftware@icehouse.net>; autox@autox.team.net
<autox@autox.team.net>
Date: Monday, October 04, 1999 6:01 AM
Subject: Re: Autocross Timing/Scoring Software
>I don't market T&S products, but I do write real-time
>software for cable set top boxes, so I'll put in $.02
>Canadian. (Geek talk ahead--delete now if you aren't
>interested--don't say I didn't warn you! :)
>
>I agree with Gary, there is no reason why a PC cannot
>be made to record T&S with 1 ms accuracy. The key is
>to set up a piece of software called an "interrupt
>service routine" so that when a signal comes in from
>the timing equipment, the PC stops what it's doing,
>records the event with time & date, and goes back to
>its business. DOS makes it easy to control hardware
>directly; Windows doesn't because it insists on
>getting its filthy paws into every ISR, and goes about
>it pretty slowly. To do this in Windows, you have to
>write a more complex code called a VxD ("virtual
>device driver" acronym in Redmondese).
>
>To be assured that this *always* happens on time, the
>computer's operating system has to be "deterministic,"
>i.e. every task it does must have a worst case
>execution time. Some of the stuff Windows does is
>unbounded in execution time (memory management being
>among the worst offenders), so you write a VxD to do
>time critical stuff because it runs at a higher
>priority than normal applications. With an operating
>system designed for real time jobs, the norm is
>*microsecond* accuracy. PC's that do real time
>control tasks like factory automation usually run an
>OS specifically designed for real time operation. T&S
>isn't that tough of a job...basically any computer
>that can run a sound card can run a *properly
>programmed* T&S system. It's just not as simple to
>write as "hello world". (If you work out how, it's a
>good way to pay for a racing habit!)
>
>Now, the next person who says "can't be done" shall be
>bound and gagged and forced to listen to me rambling
>about rate monotonic analysis! >;-)
>
>Craig Blome
>
>--- GPSoftware <gpsoftware@icehouse.net> wrote:
|