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From: johnl@haddock.UUCP
Newsgroups: net.arch
Subject: Re: Hybrid stack/register machines - (nf)
Message-ID: <135@haddock.UUCP>
Date: Fri, 23-Mar-84 23:35:34 EST
Article-I.D.: haddock.135
Posted: Fri Mar 23 23:35:34 1984
Date-Received: Sun, 25-Mar-84 13:07:59 EST
Lines: 15

#R:harvard:-17700:haddock:9500009:000:634
haddock!johnl    Mar 23 15:28:00 1984

The HP3000 series III, a fairly pure stack architecture, tries to keep
the top four entries in the stack in registers.  It physically has four
fast registers, and dynamically relabels them as the stack expands and
shrinks.  Most instructions either strictly push and pop data, or else
allow you to reference data a few words into the stack.

The manual I read (quite a while ago) suggested that this was a big
performance booster, but I've never seen a real evaluation of it.  The
3000 was hobbled by some unfortunate 64K addressing limits, so stack
speed may not have been what real users worried about much.

John Levine, ima!johnl