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Date:      Sun, 29 Aug 1999 21:55:48 -0600
From:      Wes Peters <wes@softweyr.com>
To:        Chuck Robey <chuckr@picnic.mat.net>
Cc:        Thomas David Rivers <rivers@dignus.com>, freebsd-hackers@FreeBSD.ORG, freebsd-questions@FreeBSD.ORG, kdrobnac@mission.mvnc.edu
Subject:   Re: Intel Merced FreeBSD???
Message-ID:  <37CA00C4.95ACE5D7@softweyr.com>
References:  <Pine.BSF.4.10.9908282011280.369-100000@picnic.mat.net>

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Chuck Robey wrote:
> 
> When I was in the computer architecture classes, I did a lot of
> modeling of various kinds of things that could be done to speed up a
> processor (the least of which is cache memory, but it stands as a good
> "for instance" thing here).  One thing that impressed me, when doing
> modelling of multiple different things like speculative execution and
> the IA64's rumored ability to speculatively execute several different
> paths of loop, was the extreme difficulty to adequately model how all
> the different parts work (and mis-work) together.  You end up having to
> really inspect many megabytes of output in detail, just to figure out if
> one feature worked right in one particular scenario, and I was only
> doing a relatively basic piece of modelling.
> 
> Trying to model the IA64 would have been a Manhattan Project sized task.

But they've had PLENTY of time.  HP had the 64-bit architecture defined
and a simulator underway in 1994, when Intel joined the project.  The
Merced, which is a specific chip model with the 64-bit architecture and
x86 emulator, was originally supposed to ship in late 1997.

> Honestly, I am wondering about Intel and HP's ability to really produce
> a reliable chip that had as many difficult-to-model features as the IA64
> is supposed to have.  I think that's the real reason that it's not
> actually being sampled.  Your point on the 860 is very correct, but if
> they *could* have brought the IA64 out today with the features that they
> have been promising (at the speed they promised) it would have made the
> PowerPC and the Alpha look ill

Uh, no, HP has already admitted that when Merced ships it will be slower 
than current-generation PA-RISC CPUs.  Which means it will also be slower
than Alpha, PowerPC, and UltraSPARC processors you can buy now.

-- 
            "Where am I, and what am I doing in this handbasket?"

Wes Peters                                                         Softweyr LLC
http://softweyr.com/                                           wes@softweyr.com


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