Newsgroups: comp.arch
Path: utzoo!utgpu!jarvis.csri.toronto.edu!ephemeral.ai.toronto.edu!bradb
From: bradb@ai.toronto.edu (Brad Brown)
Subject: Re: SISC
Message-ID: <89May6.165030edt.10782@ephemeral.ai.toronto.edu>
Organization: Department of Computer Science, University of Toronto
References: <112@centaure.UUCP> <422@unicads.UUCP> <11579@cgl.ucsf.EDU>
Distribution: usa
Date: Sat, 6 May 89 16:50:27 EDT

In article <11579@cgl.ucsf.EDU> seibel@cgl.ucsf.edu. (George Seibel) writes:
>In article <422@unicads.UUCP> les@unicads.UUCP (Les Milash) writes:
>>the book re-inspires me that "there are other Very Odd architectures out 
>>there waiting to be discovered; some of which are Very Useful".  After all,
>>this is the age of Very Unusual Architectured Computers, right?
>
>Hmmm... (putting on my cynic hat) I'm not so sure.  Just try to sell one.
>Seems like if anything the industry is getting more conservative.   Markets
>are certainly driven by existing software to an almost unhealthy extent,
>and this is an influence that works against unusual architectures.   This
>is not to say that a really good idea can't make it; it had just better
>be Really Good, and you'd better have deep pockets to ride out the long
>wait until it catches on.

I think Les is right, but I can't see a good way of getting over the
marketing problem.  I just finished taking a course in advanced computer
architecture, and we looked at a lot of old machines that had all kinds
of really neat features that you just don't see any more.  My favorite
was the Buroughs 6600 (?) and it's segmentation scheme.  You could do
all kinds of dynamic memory allocation basically for free, virtual memory
was a side effect of the system, and a lot of access bugs could be detected
at runtime with no performance penalty.  Unfortunately, the machine was
heavily oriented towards languages that could make use of these concepts,
like Algol or PL/1 -- I guess Pascal and Modula-II (probably Ada) could
make use of it now.

Unfortunately, a machine like this can't run C very well, 'cause C presupposes
a flat, uniform memory space.  And if you can't run C, you can't sell a 
new computer in today's market.  Furthermore, machines like this need a lot
more hardware, increasing the cost.  With minimalist RISC machines lowering
the cost of performance (and being ideal for running C programs) it would
be hard to justify a machine like this.

I think the hardest thing to do is to build a machine that is going to 
provide some really good support for programming and at the same time
be able to run a lot of differnt languages.  I see language-specific
machines like the Symbolics LISP machines ultimately failing in the 
market because they are too specialized, and the non-specialized machines
catch up to them in price-performance too quickly...

					(-:  Brad Brown  :-)
					bradb@ai.toronto.edu