Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!cica!tut.cis.ohio-state.edu!zaphod.mps.ohio-state.edu!wuarchive!swbatl!texbell!uudell!bigtex!james
From: james@bigtex.cactus.org (James Van Artsdalen)
Newsgroups: comp.arch
Subject: Re: LoadAll?
Message-ID: <26871@bigtex.cactus.org>
Date: 14 Jan 90 17:30:04 GMT
References: <597@unmvax.unm.edu> <208300003@prism>
Reply-To: james@bigtex.cactus.org (James Van Artsdalen)
Organization: Institute of Applied Cosmology, Austin TX
Lines: 20

In <208300003@prism>, rob@prism.TMC.COM wrote:

> As has been noted, the 386 and 486 can switch much more easily
> between real and protected modes, making LOADALL less useful.

LOADALL generates an illegal opcode exception (INT 6) on a 386.  I
haven't tried a 486, but I assume it does the same thing.

> Intel is pretty adamant about avoiding LOADALL, and guards
> information about it closely. I've never seen any 'official'
> documentation of it, though such documentation undoubtedly exists.

I've never understood that secrecy.  The instruction IS used by
software, notably some versions of OS/2, so a BIOS supplier for a 386
does have to know enough about it to emulate it.  I don't see what
Intel has to gain from not documenting it - lack of documentation just
slows compatible 386 BIOS development.
-- 
James R. Van Artsdalen          james@bigtex.cactus.org   "Live Free or Die"
Dell Computer Co    9505 Arboretum Blvd Austin TX 78759         512-338-8789