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From: kurt@fluke.UUCP
Newsgroups: net.micro
Subject: Re: 68020 vs. 32032, pros and cons
Message-ID: <1060@vax2.fluke.UUCP>
Date: Fri, 15-Jun-84 16:05:44 EDT
Article-I.D.: vax2.1060
Posted: Fri Jun 15 16:05:44 1984
Date-Received: Tue, 19-Jun-84 01:15:27 EDT
Organization: John Fluke Mfg. Co., Everett, WA
Lines: 40



It is true that the 16000 family is compute bound.  They typically use only
30-40 percent of the bus bandwidth available.  This makes a multiple
processor architecture convenient, but this is a side effect not a feature.

It is true that the 32032 is just a 16032 with a hacked up bus interface.
Internally the processors are identical.  Also true is that the 16032 is a
full 32 bits wide internally.  No matter what the advertising says, the
68000 is 16 bits wide inside.  Those 32-bit registers are really pairs of 16
bit registers, and the alu is 16 bits wide (explains the multiply instruction).

The 32032 is probably not as much faster than the 16032 as the 68020 will be
than the 680[01]0.  

The 16000 architecture does make it possible for the user to build a custom
slave processor.  The main processor does decode the instructions and manage
the passing of data to and from the slave.  This intellegent decision allows
the slaves to have available all addressing modes and to transfer all sizes
of operand (not just the floating point size).  It is actually a pretty good
design.

It is true that Motorola has substantially improved the microcode in the
68010.  It needed it.  Part of the change in the microcode allows the 68010
to do virtual memory (to compete effectively with the 16000).  It was almost
(but not quite) impossible to do instruction abort and restart on the 68000.
The 16000 provided this right from the start, along with an instruction set
that did not change between mask revisions like it did for the 68000.

So...I don't see that National has done any less well than Motorola in
bringing the 16000 to market (this is a real success story considering
National's checkered record in other areas).  Add to this that National did
things right from the start with the 16000, and you have my recommendation.

No affiliation with National or Motorola.  Always my own opinions.
-- 
Kurt Guntheroth
John Fluke Mfg. Co., Inc.
{uw-beaver,decvax!microsof,ucbvax!lbl-csam,allegra,ssc-vax}!fluke!kurt