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From: resnicks@netcom.UUCP (Steve Resnick)
Newsgroups: comp.os.msdos.programmer
Subject: Re: rebooting by a command, not by Ctrl-Alt-del or power off/on
Keywords: Reboot, clones
Message-ID: <22165@netcom.UUCP>
Date: 28 Jan 91 18:26:57 GMT
References: <12503@ccicpg.UUCP> <1991Jan24.183619.11120@warwick.ac.uk> <1991Jan26.122142.9747@hemel.bull.co.uk>
Organization: Netcom- The Bay Area's Public Access Unix System {408 241-9760 guest}
Lines: 51

In article <1991Jan26.122142.9747@hemel.bull.co.uk> ckaye@hemel.bull.co.uk (Chris Kaye) writes:
>bsrdp@warwick.ac.uk (Hylton Boothroyd) writes:
>
>>In article <12503@ccicpg.UUCP> mhr@ccicpg.UUCP (MHR {who?}) writes:
>>> > > I want to know how to reboot an IBM pc not by Ctrl-Alt-del, power
>>> > > off/on, or pressing the reset button methods. In other words, is
>>> > > there a command I can issue to reboot the machine
>>> > > -ping   ping@cubmol.bio.columbia.edu (128.59.128.3)
>>> >
>>> > bank@lea.csc.ncsu.edu
>>>
>>> Here is the assembly language code for both warm and cold boot
>>> simulators.
>>>
>>> warm boot:
>>> 	MOV	AX,0040
>>> 	MOV	DS,AX
>>> 	MOV	AX,1234
>>> 	MOV	[0072],AX
>>> 	JMP	FFFF:0000
>>>
>>> cold boot:
>>> 	JMP	FFFF:0000
>
>>Note that this advice depends on having:
>>        * a true blue IBM PC,
>>	* a clone in which the manufacturer's implementatation of BIOS
>>	  code has emulated the true blue behaviour at FFFF:0000 .
>>There appears to have been a period when some manufacturers felt it
>>wiser not to emulate IBM warm boot too closely for fear of copyright
>>action. The clone I use falls into that category.

Waitaminit! The code at FFFF:0000 *HAS* to reboot the computer. This is
the address where the 8086 fetches the fisrt instruction on reset. 
If the code there cannot reboot the computer, something is *VERY* wrong
with the computer, or it is not an iAPX processor. 

By the way, folks, I have been reading this newsgroup for a number of years,
and this question comes up about once every 6 weeks. This information is
in the FAQ (Frequently Asked Questions) list and Ralf Brown's Interrupt List.
 
Steve

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