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From: peter@ficc.ferranti.com (Peter da Silva)
Newsgroups: comp.arch
Subject: Re: bizarre instructions
Message-ID: <=XP95Q6@xds13.ferranti.com>
Date: 25 Feb 91 15:20:34 GMT
References: <6503@mentor.cc.purdue.edu> <12071@pt.cs.cmu.edu>
Reply-To: peter@ficc.ferranti.com (Peter da Silva)
Organization: Xenix Support, FICC
Lines: 15

In article <12071@pt.cs.cmu.edu> lindsay@gandalf.cs.cmu.edu (Donald Lindsay) writes:
> - addressing modes which studies could not find a single use of.
>   (PDP-11 autodecrement deferred - omitted from the VAX.)

Oh, that's not nearly as exciting as autodecrementing the PC. (immediate
and immediate indirect mode were implemented as autoincrement and
autoincrement deferred on the PC)

	TST	-(PC)

(on the other hand, I would expect that autodecrement deferred would have
 cost some to leave out, given the PDP-11 instruction coding).
-- 
Peter da Silva.  `-_-'  peter@ferranti.com
+1 713 274 5180.  'U`  "Have you hugged your wolf today?"