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From: mash@mips.UUCP (John Mashey)
Newsgroups: comp.arch
Subject: Re: Wirth's "challenge" (was Re: RISC)
Message-ID: <1030@winchester.UUCP>
Date: Wed, 2-Dec-87 20:48:32 EST
Article-I.D.: winchest.1030
Posted: Wed Dec  2 20:48:32 1987
Date-Received: Sun, 6-Dec-87 08:54:47 EST
References: <902@mips.UUCP> <1775@cognos.UUCP> <5157@columbia.edu> <1883@cognos.UUCP> <6877@apple.UUCP>
Reply-To: mash@winchester.UUCP (John Mashey)
Organization: MIPS Computer Systems, Sunnyvale, CA
Lines: 23

In article <6877@apple.UUCP> bcase@apple.UUCP (Brian Case) writes:

>Just in the interest of accurate information, the RT PC processor
>architecture is *very* unlike the 801 processor architecture.  The
>801 had some influence on the RT PC, but the implementation constraints
>were different.  I have heard only nth-hand information that the 801
>in unadulterated form is used as an I/O processor in mainframes.

Yes.  They basically said that they felt they had to do an
uncached design to getthe costs low enough.  That led them to go
for more dense instructions to cut down on the instruction bandwidth.
That led them to cut the number of registers from 32 to 16 (before
they did more studies that yielded the 24-28 register dropoff point).
The 801s are supposed to be channel controllers for 3090s.

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.
-- 
-john mashey	DISCLAIMER: 
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DDD:  	408-991-0253 or 408-720-1700, x253
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