🚀 go-pugleaf

rhealey@digibd.com (Rob Healey) wrote:
>	The concept of backing store strikes me as being something that
>	could have easily been prior art, but only AT&T bothered to
>	patent it? Are there any examples of backing store before 1985?
>	I think AmigaDOS has had backing store since before 1984...

Well, that's *exactly* the wrong example to choose.  AT&T's patent was
applied for 7 OCtober 1982.  The Amiga's overlapping window routines
(the layers.library) is primarily based on Rob Pike's paper.

While I was looking at patent #4,555,775, I saw an IBM patent 4,555,772
(filed 31 May 1983) which was something about multiple cursors for
multiple windows, using an Xor-writing technique.  I wonder if they
list the Xor-cursor patent as prior art?  (The local library only has
the U.S. patent register, not the full patents, so I don't know.)
-- 
	-Colin