Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!uunet!mcsun!ukc!warwick!bsrdp
From: bsrdp@warwick.ac.uk (Hylton Boothroyd)
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: <1991Jan29.110641.1670@warwick.ac.uk>
Date: 29 Jan 91 11:06:41 GMT
Sender: news@warwick.ac.uk (Network news)
Organization: Warwick Business School
Lines: 27

> > > [ assembly language code for both warm and cold boot ending
> > > 	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.
>
> Waitaminit! The code at FFFF:0000 *HAS* to reboot the computer. This
> is the address where the 8086 fetches the first 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.

In effect, the true blue behaviour offers a method of avoiding full
cold boot at FFFF:0000 before going on to the required behaviour. Not all
clones offer the true blue avoidance mechanism. And although that is
occasionally annoying, there is nothing very wrong with them!

Hylton
--
Hylton Boothroyd        Janet: h.boothroyd@uk.ac.warwick.cu
Warwick Business School Darpa: h.boothroyd%cu.warwick.ac.uk@relay-nsfnet.ac.uk
University of Warwick   Uucp:  h.boothroyd@warwick.uucp
COVENTRY, England       Earn/Bitnet: h.boothroyd%uk.ac.warwick.cu@UKACRL