Path: utzoo!utgpu!attcan!uunet!husc6!bloom-beacon!apple!baum
From: baum@Apple.COM (Allen J. Baum)
Newsgroups: comp.arch
Subject: Re: Split I and D caches and IBM lawyers
Message-ID: <15129@apple.Apple.COM>
Date: 3 Aug 88 17:36:13 GMT
References: <62370@sun.uucp> <15086@apple.Apple.COM> <62555@sun.uucp>
Reply-To: baum@apple.UUCP (Allen Baum)
Organization: Apple Computer, Inc.
Lines: 46

[]
>In article <62555@sun.uucp> dre%ember@Sun.COM (David Emberson) writes:
>In article <15086@apple.Apple.COM>, baum@Apple.COM (Allen J. Baum) writes:
>> 
>> In summary: IBM patents are not without foundation...blah blah blah

>It seems to me that in this case they patented, among other things, setting a
>bit under software control.

You are misreading my paraphrasing. They did not patent setting a bit under
software control. They patented setting a cache-line-dirty, or cache-line-valid
bit under software control in a system with split I & D caches. There is a
world of difference in that.
>
>The idea of managing the contents of a cache memory under software control 
>sounds like something that is a fundamental, obvious idea to me.

 Its very easy to say this with the benefit of hindsight. But, at the time
this was invented, it was neither fundamental, nor obvious. After all, no
one else had done it, and it was taught that caches were these invisible things
that sped up your program, and programmers couldn't tell they were there. All
of a sudden, someone (presumably) at IBM said "Lets turn it on its head- LET
the programmer know about the cache, and even be able to control it!" These 
kinds of intuition are not obvious. They're clever, and patentable. You can
argue whether IBM was in fact the first to come up with the idea. If they
weren't, you can argue whether the particular combination of features that
they have claimed (and you have to read the patent VERY carefully to catch
exactly what they are and are not claiming), but that's about all you can argue
about (on the basis of patent law). 

> I have no
>doubt that even this patent is well written.  IBM has the money to afford the
>best legal talent in the country.  But the garage entrepreneurs don't, and
>that is my major point.  The present system stifles innovation and works to
>the benefit of the largest, most powerful, richest companies.  The patent
>system was intended to protect inventors, not monopolies.

It is, unfortunately, a fact of life that big companies have more resources
that they can devote to coming up with new ways of doing things. Patent law
does not penalize big companies because they have this advantage. It does not
completely stifle innovation, or small companies, or I wouldn't be working
here! These ideas would be patentable even if a garage shop came up with them.
They are not patentable merely because a big company paid smart lawyers lots
of money to write the patent disclosure.

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