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From: jc58+@andrew.cmu.edu (Johnny J. Chin)
Newsgroups: comp.os.msdos.programmer,comp.sys.ibm.pc.misc
Subject: Re: Reboot from software
Message-ID: <kbNsLEC00UhBI0uLYL@andrew.cmu.edu>
Date: 13 Dec 90 13:44:48 GMT
References: <34681@netnews.upenn.edu>
Distribution: usa
Organization: Carnegie Mellon, Pittsburgh, PA
Lines: 35
In-Reply-To: <34681@netnews.upenn.edu>

Excerpts From Captions of msdos:
30-Nov-90  Rebooting (SUMMARY)            John Clinton Hall@wpi.WP (686)    
>In summary, to perform a system warm boot on the IBM, put the word 1234h in
>location 0040h:0072h and JMP to location 0FFFFh:0000h.  For example, the
>following Debug code performs a warm boot:
> 
>	MOV	AX,0040
>	MOV	DS,AX
>	MOV	AX,1234
>	MOV	[0072],AX
>	JMP	FFFF:0000
> 
>To cold boot the computer, just JMP 0FFFF:0000h.
>--
>The highest sounds are hardest to hear.  ## ## ## ##### ##  jhall@wpi.wpi.edu
>Going forward is a way to retreat.       ## ## ## ## ## ##  Worcester
>Great talent shows itself late in life.  ## ## ## ##### ##  Polytechnic
>Even a perfect program still has bugs.   ######## ##    ##  Institute

I hope that this little piece of assembly code will help you.
The call to INT 19h sometimes causes the system to hang, because it only
reloads the bootstrap.  If you have something memory resident at this point,
it will not get cleared and usually cause the system to hang.  The above piece
of assembly code does a reboot after clearing relocated interrupts (usually
changed by memory resident programs) and resetting memory.  Cold boot will
cause the computer to go through the system memory check that is performed
during the POST (power-on self-test); warm boot is a <ctrl-alt-del>.

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