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From: preece@uicsl.UUCP
Newsgroups: net.micro
Subject: Re: Mac: 16 or 32 bit? - (nf)
Message-ID: <5195@uiucdcs.UUCP>
Date: Fri, 27-Jan-84 22:38:56 EST
Article-I.D.: uiucdcs.5195
Posted: Fri Jan 27 22:38:56 1984
Date-Received: Tue, 31-Jan-84 02:49:17 EST
Lines: 25

#R:ihuxi:-78000:uicsl:7000045:000:1112
uicsl!preece    Jan 27 07:49:00 1984

	I have a Motorola MC68000 users manual that says
	16-bit microprocessor on the cover. All the ads for Macintosh 
	say it's a 32 bit micro... Which is it?

	Being more into hardware , I thought that having D0-D15 made
	it a 16 bit micro.
----------
This is one of those unanswerable questions.  You get to pick whether to
classify machines by register width or by external buss width.  Either
answer may give confusing results.  Consider the IBM System/360 family.
As I recall, the buss width varied by model within the family from
8 to 64 bits (this is old knowledge and subject to the decay of my
memory) and some operations dealt with up to 64 bits at a time, so
you pick a size.  It's generally thought of as a 32 bit family because
most of the registers are 32 bits and that is referred to as the word
size in the documentation.  More modern processors have more kinds of
operands, so there is no 'normal' word size.  Clearly, though, the
68000 is an order of magnitude 'bigger' than the 8088, since in both
data access width and register width it is twice as wide.

scott preece
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