From owner-freebsd-questions@FreeBSD.ORG  Tue Jun 13 16:06:06 2006
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
X-Original-To: freebsd-questions@freebsd.org
Delivered-To: freebsd-questions@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 2726816A477
	for <freebsd-questions@freebsd.org>;
	Tue, 13 Jun 2006 16:06:06 +0000 (UTC) (envelope-from pefo@opsycon.se)
Received: from orion.opsycon.se (orion.opsycon.se [212.181.93.74])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 447FD43D53
	for <freebsd-questions@freebsd.org>;
	Tue, 13 Jun 2006 16:06:04 +0000 (GMT) (envelope-from pefo@opsycon.se)
Received: from pundit.opsycon.se (pefo@pundit.opsycon.se [192.168.16.126])
	by orion.opsycon.se (8.13.4/8.13.4) with ESMTP id k5DG5kJP012987;
	Tue, 13 Jun 2006 18:05:46 +0200 (CEST)
From: Per =?iso-8859-1?q?Fogelstr=F6m?= <pefo@opsycon.se>
Organization: Opsycon AB, Sweden
To: rmk@rmkhome.com
Date: Tue, 13 Jun 2006 18:05:17 +0200
User-Agent: KMail/1.9.1
References: <200606131223.k5DCNkcB021980@toad.rmkhome.com>
In-Reply-To: <200606131223.k5DCNkcB021980@toad.rmkhome.com>
MIME-Version: 1.0
Content-Type: text/plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <200606131805.18778.pefo@opsycon.se>
X-Mailman-Approved-At: Tue, 13 Jun 2006 16:20:12 +0000
Cc: John Nemeth <jnemeth@victoria.tc.ca>, misc@openbsd.org,
	Otto Moerbeek <otto@drijf.net>, Ted Unangst <ted.unangst@gmail.com>,
	Ted Mittelstaedt <tedm@toybox.placo.com>,
	Marcus Watts <mdw@umich.edu>, freebsd-questions@freebsd.org,
	=?iso-8859-1?q?H=E1morszky?= =?iso-8859-1?q?_Bal=E1zs?=
	<balihb@ogyi.hu>, Johnny Billquist <bqt@update.uu.se>,
	netbsd-users@netbsd.org, Nikolas Britton <nikolas.britton@gmail.com>
Subject: Re: wikipedia article
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 13 Jun 2006 16:06:06 -0000

On Tuesday 13 June 2006 14:23, Rick Kelly wrote:
> Johnny Billquist said:
> >> There's actually a cheesy way to do demand paging with microprocessors
> >> that don't support demand paging (such as the original 68000--another
> >> "16 bit" machine).  The way to do this is to run two processors in
> >> parallel but skewed by one instruction.  If the first one does a bad
> >> memory fetch, then the second one will not have fetched the instruction
> >> causing the fault so contains restartable machine state.  Masscomp sold
> >> a machine like this once.
> >
> >Didn't the first Apollos do this?
>
> And also the Sun 1.

IIRC it was simpler than that. When the first cpu caused a 'miss' it was put
in wait and cpu 2 handled the pagein and then released cpu 1. Keeping the two
cpus synched, one instruction apart would have been too complicated if not
impossible...