*BSD News Article 94357


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From: dimmicmj@aston.ac.uk (Michael Dimmick)
Newsgroups: comp.unix.advocacy,comp.unix.bsd.freebsd.misc,comp.os.linux.advocacy,comp.os.linux.misc
Subject: Re: ( FreeBSD > root < Linux ) > /dev/flame
Date: 24 Apr 1997 12:14:07 GMT
Organization: Aston University
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References: <33513993.167EB0E7@sarenet.es> <5iruhb$rde@idiom.com>
  <slrn5l673t.4k.c_chaos@chaosnet.wahnapitae.on.ca> <5j2n3u$54p@idiom.com>
  <5j4c4b$sjc$4@easystreet03>
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In article <5j4c4b$sjc$4@easystreet03>,
	tedm@portsoft.com writes:
>In <5j2n3u$54p@idiom.com>, jsi@idiom.com (Michael Craft) writes:

>>It goes into 286 protected mode, I guess?  The real mode is just no 
>>good.

>Not necessairly, the '286 had the secret loadall instruction, used by
>the DOS 3.3 version of ramdisk, the IBM version of vdisk, and the DOS
>version of himem.sys.  Since the '286 could only return from
>protected mode by resetting the CPU, and real mode could only address
>the bottom 1 meg, didn't you ever wonder how you could access "XMS"
>memory on a 286 under DOS? ;-)

ISTR there's a kludge in the keyboard controller, or something, that
could be called with an I/O port addressing which would crash the
processor, whose watchdog timer would then reset it, with a special
recall routine in the BIOS that would then jump back to the right
real-mode section.  Ouch.

I also recall that it was bloody slow!  I used to have a 286 with
MS-Windows on it (v3, then v3.1) and closing down a Windows session
would take a couple of minutes...

-- 
Michael Dimmick | dimmicmj@aston.ac.uk | http://www.aston.ac.uk/~dimmicmj
".sig, .sig, wherefore art thou .sig?"