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From: mark@rtech.UUCP (Mark Wittenberg)
Newsgroups: net.arch
Subject: Re: Orthogonal addressing doesn't help multis.
Message-ID: <495@rtech.UUCP>
Date: Wed, 19-Jun-85 22:50:45 EDT
Article-I.D.: rtech.495
Posted: Wed Jun 19 22:50:45 1985
Date-Received: Fri, 28-Jun-85 01:24:14 EDT
References: <419@oakhill.UUCP> <6415@boring.UUCP>
Organization: Relational Technology, Alameda CA
Lines: 17

> > And furthermore, the orthogonal sequence is normally atomic...
> > 	Mark Wittenberg
> 
> This is untrue on machines I know of.  Typical memory-to-memory
> instructions do NOT lock out other memory cycles in between; this
> requires a specific "test-and-set" or "compare-and-swap" instruction.

I was thinking of the PDP-11 (eg, inc used the DATIO cycle) on which it
is true (unless my brain has fogged beyond repair, which is possible --
it's been several years now).  Can't think of any micros that do so, though.
Thanks for pointing this out.
-- 

Mark Wittenberg
Relational Technology
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