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From: jcburt@ipsun.larc.nasa.gov (John Burton)
Newsgroups: comp.misc
Subject: Re: AT&T owns X-windows ??  (was Re: Software Pat
Message-ID: <1991Mar12.132010.12169@news.larc.nasa.gov>
Date: 12 Mar 91 13:20:10 GMT
References: <685@newave.UUCP> <6497@auspex.auspex.com> <693@newave.UUCP>
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In article <693@newave.UUCP> john@newave.mn.org (John A. Weeks III) writes:
>In article <6497@auspex.auspex.com> guy@auspex.auspex.com (Guy Harris) writes:
>> > I have heard that someone, and it might have been ATT, obtained a pattent
>> > on using XOR to put a cursor on a terminal screen.
>
>> No, it wasn't AT&T.  Did you have any reason to believe that it was?
>
>I did, but I was slightly mistaken.  It is patent #4,197,590, owned
>by Cadtrak.  It was upheld twice in court even though the technique
>was used by others for many years before Cadtrak applied for the patent.
>As a result, Cadtrak receives several million dollars a year in user fees
>from a number of manufacturers.  Even though a 13 year might "invent" this
>technique, you better not use it unless you are willing to pay for it.
>
>-john-
>
>-- 
>===============================================================================
>John A. Weeks III               (612) 942-6969               john@newave.mn.org
>NeWave Communications                 ...uunet!rosevax!tcnet!wd0gol!newave!john
>===============================================================================

well, I guess we had better inform the Computer Science departments at the
colleges and univeristies...using XOR to place a cursor on a graphics display
is one of the basic techniques taught in Graphics I. I can point to several
textbooks that specifically mention this technique...better yet, why don't
the schools offer a course in patents, i.e. list all the "common-knowledge"
techniques that we're not allowed to use, because someone has a patent on it...
talk about a way to stifle creativity and innovation...I suppose someone
has a patent on the use of stacks and queues and symbol tables...

John Burton
(jcburt@gatsibm.larc.nasa.gov)