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From: tower@AI.MIT.EDU (Leonard H. Tower Jr.)
Newsgroups: gnu.emacs.announce,comp.emacs
Subject: [ AT&T Claims patent on part of MIT's X11 server.]
Message-ID: <9102220510.AA14333@wheat-chex>
Date: 22 Feb 91 05:10:09 GMT
Followup-To: gnu.emacs.announce
Organization: Project GNU, Free Software Foundation,
    675 Massachusetts Ave., Cambridge, MA  02139, USA   +1 (617) 876-3296
Lines: 96

  [ 1)	Please repost this in any other lists, local or netwide, where
	it would be relevant and helpful.

    2)	I wonder what prior art existed, and if it invalidates 
	AT&T's patent.


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To: unido!gnu-announce
Path: pcsbst!jkh
From: (Jordan K. Hubbard)
Newsgroups: gnu.announce
Subject: AT&T Claims patent on part of MIT's X11 server.
Date: 20 Feb 91 14:38:26 GMT
Organization: /usr1/ben/jkh/.organization

I thought that this would be of general interest, to say the least..

The following letter has been sent by AT&T to all (to my knowledge)
MIT X Consortium members, though its claims potentially affect *all*
users of The X Window System, version 11 / revision 3 and above.

To quote the letter directly (all misreferences to "X Windows"
intentionally left in):

				< Dated February 7, 1991 >

Dear <unfortunate X user>:

  AT&T is aware that your company/institution is an active
participant in the further development of the X Windows
System.  We assume that your company/institution is, or may
well be, commercially marketing or internally developing
products(s) which are based on an X Windows System

  Consequently, we bring to your attention an AT&T patent
#4,555,775 invented by Robert C. Pike and issued on November
26, 1985.  The "backing store" functionality available in the
X Windows System is an implementation of this patented
invention, therefore, your company/institution needs a license
from AT&T for the use of this patent.

  We will be pleased to discuss licensing arrangements with
the appropriate organization in your company/institution.  To
expedite these arrangements, your response should be directed

Ms. O. T. Franz at:

		10 Independence Boulevard
		Room: LL2-3A28
		Warren, New Jersey  07059-6799
		Telephone: 908-580-5929
		FAX: 908-580-6355

  We look forward to resolving this matter in the near

				Very truly yours,


				A.E. Herron
				Manager, Intellectual Property

Copy to:
L. Bearson
O.T. Franz
R.E. Kerwin


So. What more can I say? You are, of course, free to direct your
responses to those listed above.. :-)

One also wonders about other window systems using "backing store"
and the degree to which this patent will be enforced.

			PCS Computer Systeme GmbH, Munich, West Germany
	UUCP:		pyramid!pcsbst!jkh
	EUNET:		unido!pcsbst!jkh
	ARPA: or

Path: gmdzi!unido!mcsun!uunet!!bloom-beacon!
From: mo...@lightning.mcrcim.mcgill.EDU
Subject: Re:  AT&T Claims patent on part of MIT's X11 server.
Message-ID: <9102231551.AA01386@lightning.McRCIM.McGill.EDU>
Date: 23 Feb 91 15:51:15 GMT
Sender: (Mr Background)
Organization: The Internet
Lines: 20

> Consequently, we bring to your attention an AT&T patent #4,555,775
> invented by Robert C. Pike and issued on November 26, 1985.  The
> "backing store" functionality available in the X Windows System is an
> implementation of this patented invention,

Or at least so AT&T is reported to be claiming.

Has anyone looked up patent #4555775?  It seems to me it would be most
helpful to post a copy of it.

Also, have similar letters arrived in any other countries?  Any non-US
Consortium members care to speak up?

(Really.  Trying to patent backing-store.  Well, that finally puts paid
to any thoughts I might have had about buying *anything* from AT&T.)

					der Mouse

			old: mcgill-vision!mouse

Path: gmdzi!unido!mcsun!uunet!!!!kaboom
From: (Jon Maiara)
Subject: Re: AT&T Claims patent on part of MIT's X11 server.
Message-ID: <>
Date: 23 Feb 91 13:08:41 GMT
References: <9102231551.AA01386@lightning.McRCIM.McGill.EDU>
Sender: (News system)
Organization: Sons of Mr. Ed
Lines: 11
In-Reply-To: mouse@lightning.mcrcim.mcgill.EDU's message of 23 Feb 91 15:51:15 GMT

I know it's not the policy of this list's maintainers to make a
practice of answering general questions, for lack of time, but perhaps
this backing store issue warrants some kind of statement.  I would
certainly believe that one of the X gurus has heard of this patent,
and perhaps seen the application.  It might be helpful if one of the
consortium leader-types could say whether they have seen the patent
and think the claim is bogus, if they think we're doomed, or whatever.
Even if bizarre legal doings prevent this, it would still be helpful
to hear something.
---Jon Maiara <>

Path: gmdzi!unido!mcsun!uunet!!VAX1.CC.UAKRON.EDU!!!gatech!bloom-beacon!dont-send-mail-to-path-lines
From: (Richard Stallman)
Subject: Software patents
Message-ID: <>
Date: 26 Feb 91 22:29:16 GMT
Sender: (Mr Background)
Organization: The Internet
Lines: 17

While the X user community plans how to deal with the threats from
AT&T, I hope people will not think of this as a one-time isolated
problem.  It is a taste of what the future will be like.  Around 700
software patents were issued in 1989, according to the list compiled
by Glen Self.  The rate is probably still increasing.  This means that
patent problems will be commonplace for all software development.

It costs over half a million dollars to fight a lawsuit against a
patent, and not all patents can be overturned in this way.  While
tackling individual patents is worth doing, the only way to solve
the whole problem of software patents is to tackle it as a whole.

The League for Programming Freedom is a grass-roots organization of
programmers (mostly) that is working to bring back the freedom to
write programs, freedom that we had until recently.  It has both
individuals and companies as members.  For more information, write to

Path: gmdzi!unido!mcsun!uunet!!!barmar
From: (Barry Margolin)
Subject: Re:  AT&T Claims patent on part of MIT's X11 server.
Message-ID: <1991Mar6.215434.3830@Think.COM>
Date: 6 Mar 91 21:54:34 GMT
References: <9102231551.AA01386@lightning.McRCIM.McGill.EDU> <>
Sender: n...@Think.COM
Organization: Thinking Machines Corporation, Cambridge MA, USA
Lines: 28

It looks to me like AT&T's patent-infringement claim is unfounded.  Here is
an excerpt from a comment from server/ddx/mi/mibstore.c in the MIT sample

 *    This is a cross between saving everything and just saving the
 * obscued areas (as in Pike's layers.)

If this comment is correct, and if the patented algorithm is the one used
in "Pike's layers" (seems like a reasonable assumption), MIT's backing
store implementation is explicitly *not* using the patented mechanism.
Claim 9 of the patent (posted by Ritchie to comp.misc and gnu.misc.discuss
-- maybe suppose someone should copy it here) specifically says that the
terminal maintains a separate backing bitmap for each obscured area of a
window and each window maintains a list of its backing bitmaps, and claim
10 says that each backing bitmap list includes a specification of the size
and position of the window.  MIT's code only seems to maintain a single
backing pixmap per window.

Furthermore, claim 1 in the patent specifies that it deals with
*rectangular* windows.  X servers that implement the shape extension
support non-rectangular windows, and don't fall under the claims of the

Barry Margolin, Thinking Machines Corp.

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