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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.arch,net.micro.att
Subject: Re: AT&T MIPS claim
Message-ID: <6826@utzoo.UUCP>
Date: Tue, 17-Jun-86 18:00:30 EDT
Article-I.D.: utzoo.6826
Posted: Tue Jun 17 18:00:30 1986
Date-Received: Tue, 17-Jun-86 18:00:30 EDT
References: <577@scirtp.UUCP> <124@bakerst.UUCP> <583@scirtp.UUCP> <585@scirtp.UUCP>, <206@njitcccc.UUCP>
Organization: U of Toronto Zoology
Lines: 26

> You know, a lot of this discussion revolves around the assumption
> that if you want the power of a vax 11/780, one would buy a vax
> 11/780.  A friend of mine who works for DEC says that if you were
> solely interested in raw cpu power you would not buy a 780, you
> would buy the microvax II, which costs far less than the 780,
> but has 90% of its power, in cpu intensive applications...

Nobody in his right mind would buy a 780 nowadays.  And the Microvax II
isn't that impressive either; 68020 boxes from Sun or Integrated Solutions
are priced similarly and have 3-4 times the cpu crunch.

> ... the 780 is
> an all purpose performance machine (for its day).  It was designed
> to handle multitasking multiprocess environments well.  It has
> a one instruction "switch task", which I believe the 68000 lacks...

The 780 is also notorious for the interesting property that many of its
complex instructions are actually *slower* than the equivalent combination
of simple 780 instructions.  I'm not sure about "switch task", but it would
not surprise me if the 68000 does it faster.  Let's not even mention the
comparison to a well-designed RISC; Mips's machine does a TLB refill faster
in software than the 780 does it in hardware.
-- 
Usenet(n): AT&T scheme to earn
revenue from otherwise-unused	Henry Spencer @ U of Toronto Zoology
late-night phone capacity.	{allegra,ihnp4,decvax,pyramid}!utzoo!henry