[ct-user] CTDos crashing after Restarting in DOS Mode

g3rir demon g3rir at ackerley24.demon.co.uk
Sat Mar 13 10:07:58 EST 2004

When running CT on a PC which also has Win98 I use a little program
called TWEAKUI which is available from Microsoft under power toys.
Amongst many of its features it has a check box to "not start the GUI on
boot" Win98 is a gui.

Presumably Tweakui sets bootgui=0 in the system file 

I have found several problems where you think you are in DOS but you are
not really including the restart method which K3CT found. Using tweakui
it appears that you have real DOS. Any way CT works as before this way.

Neil, G3RIR

-----Original Message-----
From: ct-user-bounces at contesting.com
[mailto:ct-user-bounces at contesting.com] On Behalf Of John Bednar
Sent: 13 March 2004 04:07
To: 'CT-User List'
Subject: [ct-user] CTDos crashing after Restarting in DOS Mode

I recently changed my ham radio computer and I immediately learned
that I could no longer start CTDos using the Win98 Start | Shutdown
| "Restart in DOS" option. I have been using CTWin for several years
but it bothered me that I didn't understand what was causing this

In Dos with the above technique, CT it would crash immediately (even
before prompting for the filename). I tried several versions of
CTDos including CT9.27 and CT10.005 with the same results. The panic
crash message from CT9.27 was "Illegal Interrupt #07" along with a
short register dump. CT10.005 display a much larger panic crash
message which included "error(2001) exception 07 device not

As a test, I found that I could successfully start CTDos in a
Windows DOS window but I knew this wasn't recommended so I continued
to experiment.

In steps, I removed all memory except 128M, removed autoexec.bat &
config.sys files, set all BIOS parameters from PCI to ISA, disabled
all caching & shadowing, disabled the USB ports, removed all ISA and
PCI cards except the video card but CT still crashed. I made a
bootable DOS disk from Windows and booted from it, CTDos still

I was ready to give up but I tried one last experiment. I changed
the parameters on the hidden MSDOS.SYS and changed the BOOTGUI line
to BOOTGUI=0. This is documented on the CT Webpage and it prevents
Win98 from booting into the Windows environment from a cold start.
With this change, CTDos finally started without crashing! I tried
several DOS versions and they all started just fine. After replacing
the memory, sound card, network card, 4-port I/O card, and resetting
all the BIOS parameters, CTDos still starts just fine. 

Apparently, Win98 has a set of commands that it runs before
"Restarting in DOS mode". Something that Windows was setting on exit
was causing CTDos to crash. 

k3ct at fast.net

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