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From: u-dmfloy%sunset.utah.edu@utah-cs.UUCP (Daniel M Floyd)
Newsgroups: comp.arch,comp.edu
Subject: Why Karnough? (was Re: Computer Organization Text Needed)
Message-ID: <5692@utah-cs.UUCP>
Date: 5 Sep 88 22:09:25 GMT
References: <110@ms3.UUCP> <2930@hubcap.UUCP> <Sep.2.13.11.01.1988.24296@caip.rutgers.edu> <1764@puff.cs.wisc.edu>
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Reply-To: u-dmfloy%sunset.utah.edu.UUCP@utah-cs.UUCP (Daniel M Floyd)
Organization: University of Utah, Computer Science Dept.
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You wrote:
> [...stuff...]
>Why are Karnough maps important to computer organization?
>In fact, why would you want to use Karnough mapping on any digital system?
>
>Aside from the fact that Karnough maps are really an implementation
>technique, I think that they are no longer an apropriate tool for
>logic design for any level of hardware.
>
>I have a bunch of reasons why I think that Karnough maps are a matter of
>historical interest only, but before boring you with them I would like to
>know if anyone really uses this minimization technique any more.
>
Yes, someone still uses Karnough maps. I work for Hercules in one of
their laboratories. I have to (get to?) do a variety of tasks. I do not
design any sophisticated hardware; but once in a great while, I get
involved in some sort of low class trigger device (or similar). Usually,
there are 2 to 4 inputs (or outputs). Most of these tests are done once, or
twice, and that's all. The boss wants it done yesterday (as usual). With
K-maps I can get these done as we talk. When I get up to speak, I can look
like a hero because it's done. (Amazing what little it takes to impress
some folks.) I *could* get them done with other techniques, but I like
K-maps for these trivial problems. Anyway, I think here is one "...level
of hardware..." design where K-maps are useful and appropriate.

As for why '... Karnough maps [are] important to computer organization...',
I'd like to answer a more general question: Why is *any* minimization
technique important to computer organization?

Minimization is a method of optimization. Keep that in mind as you read
the next paragraph.

I think you'll agree that computers are *not* the result of random thought.
Computer organization is not random either. In fact, computer organization
is the results of some process whereby design goals are optimized. I'm not
saying any machine built was optimal, only that every effort was made
to optimize. Consider the famous ENIAC built by the University of
Pennsylvania, 1946 (installed 1947 at Aberdeen); or, think about
IBMs earlier 1929 Statistical Calculator. Both of these, as well
as their contemporaries, were designed for a purpose. The specific
techniques are irrelevant. The fact is, these machines were
optimized in some fashion to elliminate waste, while providing their
respective functions. The results of these and similar optimizations,
over the years, has led to the computers we have today (along with their
computer organizations).

Learning the techniques used in making design decisions, can
enhance our understanding of the design itself. With an understanding
of previous failures, and sucesses, we're better able to plan
the future. This applies to social history, political history, and
scientific (design) history.

It's sad more people aren't wise enough to apply our 20/20 hind-sight
to guide us into the future.