Path: utzoo!attcan!uunet!mcsun!cernvax!chx400!ugun2b!ugsc2a!fisher
From: fisher@sc2a.unige.ch (Markus Fischer)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Using Int 19h?
Summary: warm boot
Message-ID: <199@sc2a.unige.ch>
Date: 4 Jul 90 14:52:00 GMT
References: <90184.155514J0S@psuvm.psu.edu>
Organization: University of Geneva, Switzerland
Lines: 74

In article <90184.155514J0S@psuvm.psu.edu>, J0S@psuvm.psu.edu writes:
> I'd like to use Int 19h to perform a quick reboot of DOS to establish
> a different configuration on my Compaq 386.  The Int 19h hangs the
> machine, and I must power off/on to recover.  What do I need to do
> to get Int 19h to function?

I can't tell you why Int 19h doesn't work (or, for that matter, whether it
should work), but if you simply want to reboot your computer from software,
here are the extracts of two typical postings on the subject:

(`debug' script to create `reboot.com')
______________________________________________________________________

  Date: Mon, 16 Feb 87 15:27:48 EST
  From: John.Brennen@VI.RI.CMU.EDU
  Subject: Reboot
----
  a100
  xor ax,ax
  mov ds,ax
  mov [472],wo 1234
  jmp ffff:0

  nreboot.com
  rcx
  f
  w
  q
----------------------------------------

  The storage of 1234 in absolute memory location 00472 avoids the
  memory check.

[...]

          John Brennen            CMU Visual Inspection Lab
          jfb@vi.ri.cmu.edu       Pittsburgh, PA
-------------------------------------------------------------------

(an example in `c')
-------------------------------------------------------------------
Newsgroups: comp.sys.ibm.pc
Subject: System boot
From: jeffs@ka.excelan.com (Jeff Seideman)
Date: 11 Jan 90 21:52:13 GMT
Organization: Novell, San Jose CA.
Keywords: warm boot cold boot

For all you who requested the magic code for warm/cold booting your PC
from software, here it be:

int (far *reboot)() = (int(far *)())0xFFFF0000;
void main()
{
	unsigned far *warm;

	warm = 0x472;
	*warm = 0x1234;
	(*reboot)();
}

Note that if you set *warm to any other value it should do a cold boot.
 __________________________________________________________________________
|  ...these clouds stick to the sky      |                                 |
|  like a floating question why.         |                                 |
|  and they linger there to die.         |       Jeff Seideman             |
|  They don't know where they're going   |                                 |
|  and my friend neither do I...         |                                 |
 --------------------------------------------------------------------------


Hope this helps...

Markus Fischer, Dpt of Anthropology, Geneva