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From: kds@intelca.UUCP (Ken Shoemaker)
Newsgroups: net.arch
Subject: Re: Are "discrete" CPUs faster than VLSI?  And why?
Message-ID: <148@intelca.UUCP>
Date: Fri, 6-Dec-85 21:03:33 EST
Article-I.D.: intelca.148
Posted: Fri Dec  6 21:03:33 1985
Date-Received: Sun, 8-Dec-85 03:25:39 EST
References: <1795@peora.UUCP> <277@l5.uucp>
Organization: Intel, Santa Clara, Ca.
Lines: 27

> In article <1795@peora.UUCP>, jer@peora.UUCP (J. Eric Roskos) writes:
> > More generally, ...CPUs built with discrete
> > components (as vs. all on a single IC) tend to be faster.  This was
> > something I was skeptical of myself back during my days of faith in
> > the microprocessor, and I still tend to believe that is true largely due
> > to practical considerations than theoretical ones.
> 
> There are plenty of counterexamples to this, too...e.g. the Vax 785 and
> Sun-3, the IBM 1401 and the Apple ][, etc.  But let's restrict the
> discussion to things that were designed at the same time, in which case
> you're mostly right.
> 
> I think the reasons are complexity and generality.  VLSI chips can only

One more things: packaging technology.  It is a lot easier to put two 
128-bit wide data buses on a mainframe than it is to put the same on a 
chip with 200 pins.  This also has implications on the speed of the 
output pins in that if you try to switch too much too fast, you get pretty 
large voltage transients on the chip, which don't sit too well (so you add 
more power pins...)
-- 
yes, some uncomplicated peoples still believe this myth...

Ken Shoemaker, Santa Clara, Ca.
{pur-ee,hplabs,amd,scgvaxd,dual,qantel}!intelca!kds
	
---the above views are personal.