🚀 go-pugleaf

In article <901@nddsun1.sps.mot.com> waters@nddsun1.sps.mot.com (Mike Waters) writes:
>In article <7308:Mar605:56:5291@kramden.acf.nyu.edu> brnstnd@kramden.acf.nyu.edu (Dan Bernstein) writes:
>>In article <1991Mar5.035406.11262@visix.com> amanda@visix.com (Amanda Walker) writes:
>>> foo@elaine20.stanford.edu (castor fu) writes:
>>> >One of the things which I haven't noticed being emphasized
>}> >is that the "backing store patent" is part of a patent relating to the BLIT,
>}> >a remote graphics windowing TERMINAL.  
>}> I was wondering if that was the case.  This points even more strongly at
>}> Pike's scheme, which was done for the BLIT.  I'm beginning to suspect we
>}> just have an overzealous lawyer in AT&T's legal department...
>}Just because the patent has to do with a terminal does not mean that it
>}cannot apply to X. A patent always applies to equivalents of the
>}invention.
>
>NONSENSE! A patent applies to EXACTLY what appears in the claims - no
>more, no less.

Either way, I don't think this rules out the backing store patent being
applicable to X.  A computer running an X server is effectively a terminal.
The BLIT is just a computer running AT&T's windowing software.  The only
significant difference between an X server and the BLIT is the protocol
used at the terminal's data interface, and the patent doesn't cover that
area.

I still think the patent should be invalidated on the basis of prior art,
though.  MIT Lisp Machines had backing store in 1980, and it was documented
in the window system manual then (I wonder if anyone still has a copy of
WINDOC).
--
Barry Margolin, Thinking Machines Corp.

barmar@think.com
{uunet,harvard}!think!barmar