Message-ID:	<018201c0fa23$7e90ebc0$5608e289@mpaul>
From:	"Matthias Paul" <Matthias DOT Paul AT post DOT rwth-aachen DOT de>
To:	<opendos AT delorie DOT com>
References:	<20010613091334 DOT KVQT27981 DOT mta3-svc DOT virgin DOT net AT leo> <000701c0f5f5$f75661c0$cd08e289 AT mpaul>
Subject:	Re: multitasking gives blank screen
Date:	Thu, 21 Jun 2001 04:40:29 +0200
Organization:	University of Technology, RWTH Aachen, Germany
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>>> Can you send me (via private mail) memory dumps
>>> of C000-C7FF and E000-FFFF? 
> 
> Thanks, I have received them.

Ok, meanwhile I have received the remaining dumps
as well. Thanks, Richard.

It comes out that C800-DFFF, and E800-EFFF are free,
so you should be able to use them as UMB memory.

You might also have luck using C600/C680-C7FF,
E600-E7FF, and F660-F7FF, maybe even E000-E5FF
(in case this would really be an unused video BIOS),
however, I would not attempt to use these areas until
everything else has cleared up.

> So far we know:
> 
> EMM386 /EXCLUDE=C000-C800,E000-E7FF,F000-FFFF
> is mandantory, leaving only C800-DFFF for experiments,
> but it could still be used up by some stuff on this machine...

EMM386 /EXCLUDE=C000-C7FF,E000-E7FF,F000-FFFF
/USE=C800-DFFF,E800-EFFF

> I just want to make sure, nothing else is in there and we
> load DOS low in case this is kind of a DMA problem.
>
> I hope we will be able to see something changing,
> so we could start to build up the configuration again...

Richard reported to me, that the behaviour didn´t
change after the configuration changes. My understanding
is that this includes TASKMGR /S as well, is this correct?

I have checked your ROM BIOS on a couple of known
bugs, but could not find anything (this doesn´t mean
there were no bugs). Old Compaq´s had serious INT 13h
bugs, more recent machines were prone to video BIOS
bugs - not to speak of the partially proprietary hardware...

Please add YEAR2000=OFF to CONFIG.SYS, change
EMM386 to /DPMI=OFF, copy COMMAND.COM into
C:\DRDOS (if it isn´t there already), and change the
SHELL= directive as follows:

SHELL=C:\DRDOS\COMMAND.COM C:\DRDOS\ /E:512 /P

Please also try to play with the TASKMGR /F, /V:1,
and /V options, just in case this is a video problem.

If this still does not work, TASKMGR would prove
to be incompatible with your Compaq 386, unfortunately.

I would be interested to find out, if you can still switch
tasks when the task switcher is controlled from an
external program, even when the TASKMGR menu
does not show you more than one task. If you like
I can send you a little test tool via private mail.

All else you could do is optimizing your configuration
for non-TASKMGR work, and trying to use a different
task switcher or multitasker, including DESQview,
PC Tools Shell or MS-DOS 6+ DOSSHELL,
or Windows 3.xx DOS-Boxes...

Greetings,

 Matthias

-- 

Matthias Paul, Ubierstrasse 28, D-50321 Bruehl, Germany
<mailto:Matthias DOT Paul AT post DOT rwth-aachen DOT de>; <mailto:mpaul AT drdos DOT org>
http://www.uni-bonn.de/~uzs180/mpdokeng.html; http://mpaul.drdos.org

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