From:	pekangas AT sci DOT fi (Petteri Kangaslampi)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Losing interrupts under NT or what ?
Date:	24 Jan 1997 12:09:23 GMT
Organization:	Scifi Communications International Oy, http://www.sci.fi/, helpdesk AT sci DOT fi, 03 2899111
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Message-ID:	<slrn5eh9l2.6gh.pekangas@sci.fi>
References:	<32E89982 DOT 5C11EFE7 AT ensica DOT fr>
Reply-To:	pekangas AT sci DOT fi
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

On Fri, 24 Jan 1997 12:14:10 +0100, Fabrice Frances <frances AT ensica DOT fr> wrote:
>I have a program reprogramming the timer's interrupt interval to 50 Hz and I
>catch the Timer's interrupt in order to synchronize my program's behavior.
>[...]

As a rule, DOS programs simply cannot access the hardware under Windows
NT. There some exceptions, such as the VGA, but usually the port writes
and whatnot are just ignored. The timer in particular does this - you can
hook the interrupt OK, but it runs steadily at 18.2Hz no matter what you
do.

So, yeah, this renders NT pretty useless for running many DOS
applications, but that's what DOS is for :)

Note that the timer isn't very safe to use under Windows 95 either. First
of all, you can't read the timer counters reliably, and, secondly, it
seems that setting the counter doesn't reset the countdown in any of the
modes as it should - timer count changes take effect one interrupt "late".
Running a timer at a steady XX Hz works OK though.


Petteri


PS, on a completely unrelated note, I actually have a small part of MIDAS
working with DJGPP. The only sound card supported is the Gravis
UltraSound, and it plays pretty strange remixes of the actual music, so
it's not quite ready for release yet :)

PPS, anybody know if any of the object module converters actually work
enough to be useful? Our patented tasm|wdisasm|sed|gcc - converter seems
to loose quite a bit of stuff like initialized variables...

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