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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.micro
Subject: Re: 4->8->16->32->64? bit micros
Message-ID: <4845@utzoo.UUCP>
Date: Sat, 29-Dec-84 20:17:51 EST
Article-I.D.: utzoo.4845
Posted: Sat Dec 29 20:17:51 1984
Date-Received: Sat, 29-Dec-84 20:17:51 EST
References:  <280@oakhill.UUCP> <256@tekigm.UUCP>, <274@desint.UUCP>
Organization: U of Toronto Zoology
Lines: 19

The question is not whether 64-bit numbers have uses, but whether they
have enough uses to justify the costs of making them all-pervasive.
The arguments for having them seem significant, but the arguments for
making them the basic type seem weak.  Note that 16 bits is in fact
enough for a lot of variables, if 32 is available for the exceptions;
the push from 16 to 32 came from addresses, not data.  Whether we will
eventually start to find 32-bit addresses confining is an interesting
question.  (Except in specialized areas where it's a foregone conclusion,
like bulk number-crunching -- *those* machines have had monster address
spaces for quite a while.)  It is clear that 32 bits will suffice for
the next little while; whether the past growth in space requirements
will continue past 32 is harder to predict.  It might.

An interesting sidelight on this:  if you're wondering why the 68000
has that silly separation between A and D registers, it's because the
first 68000 design had 16-bit D registers but bigger A registers.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry