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From: tim@callan.UUCP (Tim Smith)
Newsgroups: net.micro.mac
Subject: Re: high byte of address question
Message-ID: <292@callan.UUCP>
Date: Tue, 22-Jan-85 18:00:43 EST
Article-I.D.: callan.292
Posted: Tue Jan 22 18:00:43 1985
Date-Received: Fri, 25-Jan-85 21:34:05 EST
References: <224@ucbopal.CC.Berkeley.ARPA> <130@redwood.UUCP>
Reply-To: tim@callan.UUCP (Tim Smith)
Organization: Callan Data Systems, Westlake Village, CA
Lines: 15
Summary: 

In article <130@redwood.UUCP> rpw3@redwood.UUCP (Rob Warnock) writes:
>+---------------
>| programming in assembly language to handle some special cases.  I've
>| noticed that the high byte of an address (the 68000 only uses the bottom
>| 24 bits) is used alot in the Mac for special purposes.  However, even when
>+---------------
>NO, NO! SAY IT ISN'T SO! If they have done this, it's going to be a major
>disaster when they go to a 68020, where those bits are significant. Don't

They could always just leave the upper eight address lines unhooked
on the 68020, thereby staying compatible! :-)
-- 
Duty Now for the Future
					Tim Smith
			ihnp4!wlbr!callan!tim or ihnp4!cithep!tim