🚀 go-pugleaf

jeffrey@algor2.algorists.com.ALGORISTS.COM (Jeffrey Kegler) writes:
>I visited the Sunnyvale branch of the Patent Office Friday, and, after
>some difficulty, was able to copy Patent 4,555,775, "Dynamic
>Generation and Overlaying of Graphic Windows for Multiple Active
>Program Storage Areas", aka The Backing Store Patent.

Thanks you!  I'm still trying to get a chance to find it myself, so
that I can see the entire text, but at least now there is some hard
information to work with.

Claim 7 sounds like it would cover any X terminal, or workstation
running a window system, or even Apple's MultiFinder.  Seems a little
broad :).

>5.)  The whole thing is sloppily thrown together.  Column 9, line 54,
>the empty parentheses designating a function name are astride a line
>break, with the closing parenthesis starting a new line.  Column 4,
>line 29 tells us of "an obscured bitmap list comprising nothin [sic]
>more that a sequence of pointers to the obscured bitmap areas."

Aha.  Now *this* sounds like a description of Pike's nifto-keano
backing store scheme (whereby you don't have to store  entire
window's contents offscreen, just the obscured parts).  If this
is in fact a limitation of the patent's scope, things may not be too
bad, although folks like NCD (and other providers of memory-poor X
servers) might want to license the patent anyway.

Pike's approach is very memory-efficient, but it's certainly not the
only good way to manage backing store...

-- 
Amanda Walker						      amanda@visix.com
Visix Software Inc.					...!uunet!visix!amanda
--
If the designers of X-window built cars, there would be no fewer than five
steering wheels hidden about the cockpit, none of which follow the same
principles - but you'd be able to shift gears with your car stereo.  Useful
feature, that.  [From the programming notebooks of a heretic, 1990]