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Path: utzoo!watmath!clyde!cbosgd!ihnp4!mhuxn!mhuxj!mhuxr!ulysses!allegra!mit-eddie!genrad!decvax!tektronix!orca!mako!jans
From: jans@mako.UUCP (Jan Steinman)
Newsgroups: net.micro.68k
Subject: Re: 32 vs. 24 Bit Addresses
Message-ID: <608@mako.UUCP>
Date: Thu, 28-Feb-85 17:35:38 EST
Article-I.D.: mako.608
Posted: Thu Feb 28 17:35:38 1985
Date-Received: Mon, 4-Mar-85 04:37:55 EST
References: <342@oakhill.UUCP>
Reply-To: jans@mako.UUCP (Jan Steinman)
Organization: Tektronix, Wilsonville OR
Lines: 12
Summary: 

In article <342@oakhill.UUCP> cruess@oakhill.UUCP (Michael Cruess) writes:
>As an aside, having 32 bit addresses designed into the M68000  Family  from
>the beginning has made the instruction set upgrade in the MC68020 easy...

I know of a 68010 software project that DEPENDS on those bits being
masked off chip.  It uses the eight most significant bits of pointers to
objects as flags that contain information obout those objects.  Of course,
if a usable Motorola MMU is available when they port to the 68020, they can
simply fold that huge address space over...
-- 
:::::: Jan Steinman		Box 1000, MS 61-161	(w)503/685-2843 ::::::
:::::: tektronix!tekecs!jans	Wilsonville, OR 97070	(h)503/657-7703 ::::::