🚀 go-pugleaf

In article <Oct05.024017.52366@yuma.ACNS.ColoState.EDU> barnesdo@CS.ColoState.EDU (douglas barnes) writes:
>Periodically people make reference to the "XOR" patent on this
>and other groups. Are they referring to a couple of patents
>held by the CADTRAK corporation that deal with issues such as
>double-buffering, scrolling, video enlargement and cursor movement?

I believe this (from prep.ai.mit.edu:/pub/lpf/patent-list) is the "XOR
patent":

  4,197,590
  Method for dynamically viewing image elements stored in a random access
  memory array
  filed 1/19/78
  granted 4/8/80
  inventors Josef S. Sukonick; Gred J. Tilden
  assignee NuGraphics, Inc.
  Includes claims of "XOR feature permits part of the drawing to be moved or
  'dragged' into place without erasing other parts of the drawing."
  Twice upheld in court.  [Cadtrak now owns this?]

>Last I heard they were embroiled with Commodore, and the case was dragging 
>out considerably. Does the XOR patent == the CADTRAK patents, or
>am I confusing two different creatures? I have also heard of a
>"backing store" patent, and even an "XOR backing store patent". Where
>do these fit in, or is someone else even more confused than I am?

Here's the entry on the backing store patent:

  4,555,775
  Dynamic generation and overlaying of graphic windows for multiple active
  program storage areas
  filed 10/7/82
  granted 11/26/85
  inventor Robert C. Pike
  owner AT&T

By the way, now that I've posted this, I should retract an earlier
statement (perhaps made in some other newsgroup such as gnu.misc.discuss or
comp.org.eff.talk), which I've seen others quoting, that the backing store
patent never uses the word "window" (using AT&T's term "layer"); if nowhere
else, it uses the word "window" in the title of the patent, quoted above.

I think the person who referred to an "XOR backing store patent" was either
confused or meant to type "XOR and backing store patents".

-- 
Barry Margolin
System Manager, Thinking Machines Corp.

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