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From: crowl@cs.rochester.edu (Lawrence Crowl)
Newsgroups: comp.lang.c,comp.arch
Subject: Was the 360 badly-designed?  (was Re: Compatibility with EBCDIC)
Message-ID: <1580@sol.ARPA>
Date: Fri, 21-Aug-87 16:42:17 EDT
Article-I.D.: sol.1580
Posted: Fri Aug 21 16:42:17 1987
Date-Received: Sun, 23-Aug-87 03:04:02 EDT
References: <855@tjalk.cs.vu.nl> <2683@hoptoad.uucp>
Reply-To: crowl@cs.rochester.edu (Lawrence Crowl)
Organization: U of Rochester, CS Dept, Rochester, NY
Lines: 49
Xref: mnetor comp.lang.c:3806 comp.arch:1858

crowl@cs.rochester.EDU (Lawrence Crowl) writes:
>..., are you implying the 360 architecture was badly designed?  This claim
>will need VERY good arguments to over-ride 25 years (almost) of success.

mjr@osiris.UUCP (Marcus J. Ranum) writes:
)Stone hammers, along with flint knives, showed more success (in years) than
)EBCDIC architecture, but nobody uses them anymore.  Only the trailing edge of
)technology still supports 360 architecture...  Arguing that your flint axe has
)had '2000 years of success' is not going to change the fact that the times
)have changed.  Do you also favor laser-optical card reader technology ?

Yes, stone hammers and flint knives were used for a very long time.  Their
performance has not improved.  Implementations of the 360 architecture have
improved immensly.

On the contrary, the leading edge of technology supports the 360 architecture.
Some of the fastest scalar machines available are based on the 360.

Yes, times have changed, but "well-designed" is relative to the time at which
the design was done.  Roman roads were well-designed.  No one builds them any
more, but they were still well-designed.

dhesi@bsu-cs.UUCP (Rahul Dhesi) writes:
]The misconception here is that a broad user base implies high quality or
]elegance of design.  Instead of offering VERY good arguments, I will simply
]offer three counterexamples without further comment.
]1.   The 8086 family of CPUs versus the 680x0 family of CPUs
]2.   The National Enquirer versus the Wall Street Journal
]3.   Family Feud versus the MacNeil/Lehrer Report

I had no misconception, and these are not counter-examples.  I did not state
that something had to be well-designed to be popular.  Nor are popular things
necessarily poorly-designed.  Popular and well-designed are loosely related.

I am not necessarily stating that the 360 architecture was well-designed, but I
am saying the architecture has shown flexibility and adaptability for many
years.  If you wish to say the 360 architecture is bad, you must show why its
adaptability is illusory.  The 360 architecture has been implemented on
machines spanning roughly two orders of magnitude in performance.  It has gone
from physical memory to virtual memory.  It supported a virtual machine long
before many other architectures did.  

I repeat my statement: one needs VERY good arguments to claim that the 360
architecture was badly-designed.  Anyone care to provide them or refute them?
I have added comp.arch since they are likely to provide interesting input.
-- 
  Lawrence Crowl		716-275-8479	University of Rochester
		     crowl@cs.rochester.arpa	Computer Science Department
 ...!{allegra,decvax,seismo}!rochester!crowl	Rochester, New York,  14627