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From: abaum (Allen Baum)
Newsgroups: comp.arch
Subject: Re:2.5 Addr Archs
Message-ID: <165@armltd.uucp>
Date: 9 May 91 10:31:15 GMT
References: <673707950@romeo.cs.duke.edu>
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Distribution: comp
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 (D. Richard Hipp) writes:


>I once proposed an architecture that featured "2.5" addresses...
> Each instruction contains two register numbers, plus one extra bit
>which indicated whether the ... (destination) should be the
>same as A or should be register zero (the accumulator)

>This was only an idea, and was never tested.  I would be interested to hear
>if John Van Zandt, or anyone else, has ever looked at this addressing scheme
>and what they found after looking at it for a while.

The ATT CRISP has instructions of this form, as did the Lawerence Livermore Labs
S-1 machine.