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Date: Wed, 15 Apr 1998 21:08:01 GMT
From: pete@dunnington.u-net.com (Pete Turnbull)
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In-Reply-To: allisonp@world.std.com (Allison J Parent)
        "Re: PDP-11 Addressing Modes" (Apr 14, 23:53)
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On Apr 14, 23:53, Allison J Parent wrote:
> <What do people here on the list think of the flexibility and
> <generality of the PDP-11's addressing modes?  Is this a well thought
> <out architecture in your view?  How are the PDP-11's addressing modes
> <better or worse than those of other processors, past and present?
>
> Personally I consider it a high point in 16 bit computing and one that
> is a standard of comparison.  VAX carried this to the 32bit realm.  I
> know of few 16 bit microprocessors that are as capable as the PDP-11
> and as fast (the ti9900 was good but slow, Z8000 was close).

Don't forget the 68000.  Motorola deliberately adopted a lot of similar design
features for the 68K; there's a very interesting design paper still available
called "Design Philosophy Behind Motorola's 68000", publication no.AR208.  The
same sort of instruction/address-mode orthogonality as found in the PDP11, is
one of the big features.

> Terrible cpu, we should junk them all... ;-)   ...so I can collect them.

All right, providing I can have the ones on this side of the Atlantic...

-- 

Pete						Peter Turnbull
						Dept. of Computer Science
						University of York