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From: jeff@aiai.ed.ac.uk (Jeff Dalton)
Subject: Re: Why do people like C? (Was: Comparison: Beta - Lisp)
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References: <Pine.A32.3.91.941018090811.17296C-100000@swim5.eng.sematech.org> <Cy1HHG.5Mz@cogsci.ed.ac.uk> <Pine.A32.3.91.941024091829.14402C-100000@swim5.eng.sematech.org>
Date: Wed, 26 Oct 1994 17:44:37 GMT
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In article <Pine.A32.3.91.941024091829.14402C-100000@swim5.eng.sematech.org> "William D. Gooch" <goochb@swim5.eng.sematech.org> writes:
>On Fri, 21 Oct 1994, Jeff Dalton wrote:
>
>> In article <Pine.A32.3.91.941018090811.17296C-100000@swim5.eng.sematech.org> "William D. Gooch" <goochb@swim5.eng.sematech.org> writes:
>> >On Mon, 17 Oct 1994, Jeff Dalton wrote:
>> >
>> >> ...
>> >> But for how long could specialized/specially-microcoded machines
>> >> continue to be faster than the alternatives?
>> >
>> >For as long as someone is willing to put a small fraction of the effort 
>> >into making the chips go faster as they do for stock chips.  Lisp 
>> >hardware has not been pushed anywhere near as far up the performance 
>> >curve as it can be.  

Part of the problem is that the smaller market tends to mean they
won't be pushed as far.

>> The specialized / micorcoded machines should do worse than CISC
>> machines against RISC.  Many of the same factors are involved.
>> I have no doubt that a simple (in the RISC sense) and fast Lisp
>> machine could be developed.  But that isn't what people were doing
>> in the early 80s when microcode was all the rage.
>
>What do you think they were doing?

Developing specialized, micro-coded machines.  If you tell me
symbolics machines were RISC, I may have to believe you; but
it seems very unlikely to me.

Look, I don't *know* the answers.  I'm saying how it seemed to me.
But we have to consider that in the early to mid 80s lots of people
were developing specialized, micro-coded machines and that they 
aren't doing it now.  Some specialized machines were slower than
emulations on not-very-fast Suns.  

There's no doubt that some specialized machines were fast and had
strong advantages at the start.  You point out that Symbolics machines
"were quite price/performance competetive when they were new."
That's not in dispute, so far as I'm concerned.  They may also
be competitive *now*, since there seem to be a number of unwanted
used ones available.

But so far as I can tell such machines were overtaken by ordinary
machines and then by RISC machines as the 80s went on.  For some
people, who wanted the Lisp machine environment, Lisp machines 
remained competitive, because they couldn't get equivalent features
on mainstream machines.  But for many people Lisp machines seemed
very expensive and limited in what they could do.  That they could
run Lisp fast didn't matter all that much because there were other
machines that could run Lisp well enough.

>I guess I don't know enough about hardware to carry this discussion much 
>further.  However, since the Symbolics Ivory architecture has quite a bit 
>of Lisp implemented directly in the hardware, I think your conclusion may 
>not be correct.  In terms of complexity, the Ivory chip is not bad.  I 
>don't remember the exact numbers, but I seem to recall that it is similar 
>to a 486 in number of components on the chip, but that a much smaller 
>percentage of them are memory on an Ivory.

But vastly more 486s would be made, and this tends to help make
them faster.  Indeed, w/ the 586 (Pentium), Intel may be showing
that non-RISC can still compete (though in part by taking on similar
techniques).

-- jeff
