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From: mash@mips.UUCP (John Mashey)
Newsgroups: comp.arch
Subject: Re: Wirth's challenge (was Re: RISC)
Message-ID: <1047@winchester.UUCP>
Date: Fri, 4-Dec-87 01:20:22 EST
Article-I.D.: winchest.1047
Posted: Fri Dec  4 01:20:22 1987
Date-Received: Wed, 9-Dec-87 03:23:50 EST
References: <902@mips.UUCP> <1775@cognos.UUCP> <5157@columbia.edu>
Reply-To: mash@winchester.UUCP (John Mashey)
Organization: MIPS Computer Systems, Sunnyvale, CA
Lines: 41

In article <6892@apple.UUCP> baum@apple.UUCP (Allen Baum) writes:
>--------
>>However, you can buy 2 machines that are clearly 801-descendents:
>>HP Precision and MIPS R2000, which, as far as I can tell, are the
>>closest ones on the market to the 801.  Whenever it comes out, the
>>78000 has a lot of similarities also.

>The only way that the HP Precision architecture can be considered is in spirit.
>Although there were former IBM'ers on the project, they weren't allowed to talk
>about it at all, and they didn't. To this day, I haven't talked with anyone
>who would tell me any details on the 801 architecture. Some details did come
>out in the papers at the ASPLOS conference, but they did not influence any
>of the design decisions on the Precision.

Sorry, I meant absolutely no hint that proprietary info got moved,
and I did mean in spirit, especially of methodology of starting with
serious optimizing compiler technology and doing substantial analysis.
It is extremely interesting that there was no influence from the
March 1982 Radin paper at ASPLOS; I would have thought that it would have
been analyzed thoroughly at least for confirmation of direction,
but I wasn't there, so I believe you.

Certainly, it is interesting that both 801 and Spectrum used
optimizing compiler-driven design,
32 registers,
32-bit instructions,
separate I&D caches,
and no windows.
(MIPS can't be included as independent: we certainly had access to the
published 801 documents before we started.)

Either the similarities arise from the limited choices once you've
made some of those decisions, or, starting from some of the same assumptions,
and proceeding with realted methodologies, you get to somewhat similar
designs.  [There are of course all sorts of little differences amongst
the 3 machines mentioned, but if you take the universe of RISC machines,
they look more similar than most.]
-- 
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