Subject: Re: ddb key sequence
To: John F. Woods <>
From: John Nemeth <>
List: current-users
Date: 11/12/1994 03:48:49
On Nov 11,  9:25am, "John F. Woods" wrote:
} Subject: Re: ddb key sequence
} > >What is the key sequence for getting into the kernel debugger, ddb?
} > I believe it's ctrl-alt-esc.
} An NMI is also supposed to do it (if the keyboard is locked up).
} Alas, I don't know how to generate an NMI (my motherboard's "manual"
} doesn't admit to the existance of a tie point for it or anything).

     If you look at any slot on an ISA machine, with the front of the
machine facing towards you, the last pin on the right nearest the back
of the machine is the I/O Channel Check pin.  Momentarily grounding
this pin will produce an NMI.  Under DOS, if not redirected, the BIOS
would report this as an Off Board Parity Error and halt the machine.
Periscope, a company that makes DOS debuggers, sells a switch for this
purpose, intended for forcing an entry to their debugger.  You could
rig up something yourself.  You need a normally open pushbutton switch
with one wire going to a good ground point and another wire going to a
slot, stick it in the slot then stick in a card being real careful not
to short adjacent pins.

Disclaimer:  I'm not responsible if you blow up your computer by
following these instructions.

}-- End of excerpt from "John F. Woods"