new divide by zero errors in 1.1.5

new divide by zero errors in 1.1.5

[Daniel Greenberg]

Here is an interesting problem that shows itself in 1.1.5
and not in 1.1.4 or earlier versions of dosemu.

Certain programs (e.g., MSD.EXE, Word for Dos version 5.0)
fail with a divide by zero error message at startup.  (The error message
comes from within the dos session - dosemu itself doesn't crash.)
These programs started fine under previous versions of dosemu.
What is strange is that I can avoid these divide by zero errors if I start
and then exit certain other programs (e.g. paradox, edit, /dos/help,
dosshell) before trying to start Word or MSD.

Though I'm not certain, I suspect that when these other programs exit
they are restoring the video mode in some beneficial manner.

Dan Greenberg
Ann Arbor, MI

Re: new divide by zero errors in 1.1.5

[Bart Oldeman]

On Sun, 8 Jun 2003, Daniel Greenberg wrote:

> Here is an interesting problem that shows itself in 1.1.5
> and not in 1.1.4 or earlier versions of dosemu.

can you check 1.1.4.15 (www.dosemu.org/testing) to see if it is new or
really new?

> Certain programs (e.g., MSD.EXE, Word for Dos version 5.0)
> fail with a divide by zero error message at startup.  (The error message
> comes from within the dos session - dosemu itself doesn't crash.)
> These programs started fine under previous versions of dosemu.
> What is strange is that I can avoid these divide by zero errors if I start
> and then exit certain other programs (e.g. paradox, edit, /dos/help,
> dosshell) before trying to start Word or MSD.
>
> Though I'm not certain, I suspect that when these other programs exit
> they are restoring the video mode in some beneficial manner.
>

are you running DOSEMU on the console or in X (xdosemu)?
if you run it on the console, does $_vbios_post make any difference?

Bart

Re: new divide by zero errors in 1.1.5

[Daniel Greenberg]

Thanks Bart for your reply and questions.  Here are the answers:

I get these divide-by-zero errors only from xdos, not from the console.
So when running DOS from the console the $_vbios_post setting
doesn't matter.  (Though setting $_vbios_post = (0) lets me avoid some
really nasty system crashes and lockups I was having with console
mode dosemu!)

It turns out the divide-by-zero problem isn't "really new," just new.
That is, 1.1.4.15 has the problem, but 1.1.4.0 is fine.  I picked
something in the middle - 1.1.4.8 - and found that it too had the "new"
divide-by-zero errors.  A couple more downloads and compiles and I
was able to isolate the introduction of the problem to 1.1.4.7.  That is,
1.1.4.6 runs without the "new" divide-by-zero errors, while
1.1.4.7 runs with the errors.  So apparently 1.1.4.7 was the first to
introduce this problem.

Hope this helps.

(By the way, I love the new full-screen xdos option!)

Thanks,

Dan Greenberg


----------------------------------------------------------------~
On Sun, 8 Jun 2003, Bart Oldeman wrote:

> On Sun, 8 Jun 2003, Daniel Greenberg wrote:
>
> > Here is an interesting problem that shows itself in 1.1.5
> > and not in 1.1.4 or earlier versions of dosemu.
>
> can you check 1.1.4.15 (www.dosemu.org/testing) to see if it is new or
> really new?
>
> > Certain programs (e.g., MSD.EXE, Word for Dos version 5.0)
> > fail with a divide by zero error message at startup.  (The error message
> > comes from within the dos session - dosemu itself doesn't crash.)
> > These programs started fine under previous versions of dosemu.
> > What is strange is that I can avoid these divide by zero errors if I start
> > and then exit certain other programs (e.g. paradox, edit, /dos/help,
> > dosshell) before trying to start Word or MSD.
> >
> > Though I'm not certain, I suspect that when these other programs exit
> > they are restoring the video mode in some beneficial manner.
> >
>
> are you running DOSEMU on the console or in X (xdosemu)?
> if you run it on the console, does $_vbios_post make any difference?
>
> Bart
>
>

Re: new divide by zero errors in 1.1.5

[Bart Oldeman]

On Mon, 9 Jun 2003, Daniel Greenberg wrote:

> It turns out the divide-by-zero problem isn't "really new," just new.
> That is, 1.1.4.15 has the problem, but 1.1.4.0 is fine.  I picked
> something in the middle - 1.1.4.8 - and found that it too had the "new"
> divide-by-zero errors.  A couple more downloads and compiles and I
> was able to isolate the introduction of the problem to 1.1.4.7.  That is,
> 1.1.4.6 runs without the "new" divide-by-zero errors, while
> 1.1.4.7 runs with the errors.  So apparently 1.1.4.7 was the first to
> introduce this problem.

Thanks, that narrows it down a bit. I suspect that the initialization
(which was shuffled around a little in 1.1.4.7) is the culprit, but I
fail to see where.

Can you make hexdumps of the area from 0:0 to 0:500 for both DOSEMU's
(using DEBUG in DOS or using dosdebug with the "d" command) and see if
there are any differences, beyond the timer (4 bytes at 0:46c) and the
keyboard buffer (0:41a- - 0:43d)?

Bart

Re: new divide by zero errors in 1.1.5

[Daniel Greenberg]

On Mon, 9 Jun 2003, Bart Oldeman wrote:

> On Mon, 9 Jun 2003, Daniel Greenberg wrote:
>
> > It turns out the divide-by-zero problem isn't "really new," just new.
> > That is, 1.1.4.15 has the problem, but 1.1.4.0 is fine.  I picked
> > something in the middle - 1.1.4.8 - and found that it too had the "new"
> > divide-by-zero errors.  A couple more downloads and compiles and I
> > was able to isolate the introduction of the problem to 1.1.4.7.  That is,
> > 1.1.4.6 runs without the "new" divide-by-zero errors, while
> > 1.1.4.7 runs with the errors.  So apparently 1.1.4.7 was the first to
> > introduce this problem.
>
> Thanks, that narrows it down a bit. I suspect that the initialization
> (which was shuffled around a little in 1.1.4.7) is the culprit, but I
> fail to see where.
>
> Can you make hexdumps of the area from 0:0 to 0:500 for both DOSEMU's
> (using DEBUG in DOS or using dosdebug with the "d" command) and see if
> there are any differences, beyond the timer (4 bytes at 0:46c) and the
> keyboard buffer (0:41a- - 0:43d)?
>
> Bart
>
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Comparing 1.1.4 & 1.1.5 the only difference I found was at 0:01C.  This is
in the interrupt vector table, no?  Not sure the significance of this
though. Otherwise - with the exception of the timer and keyboad buffer -
they are identical.

Dan