Path: utzoo!attcan!uunet!sco!seanf
From: seanf@sco.COM (Sean Fagan)
Newsgroups: comp.arch
Subject: Re: 386 Clones
Message-ID: <8455@scolex.sco.COM>
Date: 28 Oct 90 09:04:42 GMT
References: <10833@pt.cs.cmu.edu>
Sender: news@sco.COM
Reply-To: seanf (Sean Fagan)
Organization: The Santa Cruz Operation, Inc.
Lines: 23


In article <10833@pt.cs.cmu.edu> lindsay@gandalf.cs.cmu.edu (Donald Lindsay) writes:
>I would have nominated the 286 emulation as the killer, since the
>native mode is mostly "more of the same" with paging.  

I wouldn't.  There's little difference between the 16-bit (protected) mode
and the 32-bit (protected) mode, except for sizes and addresses.  All of the
same operations and checks come into play for both; the only difference is a
bit set in the segment descriptor which says, for example, that registers
are 16-bits or 32-bits, and granularity is byte or page, or somesuch.  Note
that these are different bits, so you can have 32-bit registers, but still
be limited to 16Mb through 64K segments.

The problem is *getting* the [23]86 stuff in the first place.  Once you've
got the basics, getting the other isn't that difficult (or doesn't seem so,
to me).  But the basic architecture is a bitch, to be sure...

-- 
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Sean Eric Fagan  | "*Never* knock on Death's door:  ring the bell and 
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