Path: utzoo!utgpu!water!watmath!clyde!bellcore!rutgers!tut.cis.ohio-state.edu!mandrill!neoucom!wtm
From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: comp.sys.ibm.pc
Subject: Re: ???=>reBoot from a batch file?????
Summary: The BIOS warm boot magic-cookie trick
Message-ID: <1249@neoucom.UUCP>
Date: 2 Jun 88 15:22:45 GMT
References: <5537@megaron.arizona.edu> <32505@amdahl.uts.amdahl.com>, 
Organization: Northeastern Ohio Universities College of Medicine
Lines: 38


If you jump into the the BIOS with location 0040:0072H set to the
magic quatity of 1234H, and jump to the entry point of the BIOS,
the system will perform a warm boot (i.e., no power-on self-test,
etc.).  Putting anything else in that memory location will force a
cold boot.

You can use DEBUG to enter the following sequence and save the
result as WARMBOOT.COM:

The blank line in the script below is necessary to get out of
assemble mode!

---------------------- cut here -------------------------
a 0
mov ax,0040
mov ds,ax
mov ax,1234
mov [0072],ax
jmp f000:fff0

r cx
16
n warmboot.com
w
q
---------------------- end of script ---------------------


Clip the above section out and save it in a text file.  Then, redirect
the text file into DEBUG thusly:  debug < file.txt.  This will
automatically feed the commands in and create warmboot.com.  Of
course, you can always type the same sequence manually from your
keyboard.  INT 19H is brain damaged on most clone computers.  I've
yet to find a machine that the above method won't work on.

--Bill
  wtm@neouocm.UUCP